USENIX Security '24 Fall Accepted Papers

Database Management Systems play an indispensable role in modern cyberspace. While multiple fuzzing frameworks have been proposed in recent years to test relational (SQL) DBMSs to improve their security, non-relational (NoSQL) DBMSs have yet to experience the same scrutiny and lack an effective testing solution in general. In this work, we identify three limitations of existing approaches when extended to fuzz the DBMSs effectively in general: being non-generic, using static constraints, and generating loose data dependencies. Then, we propose effective solutions to address these limitations. We implement our solutions into an end-to-end fuzzing framework, BUZZBEE, which can effectively fuzz both relational and non-relational DBMSs. BUZZBEE successfully discovered 40 vulnerabilities in eight DBMSs of four different data models, of which 25 have been fixed with 4 new CVEs assigned. In our evaluation, BUZZBEE outperforms state-of-the-art generic fuzzers by up to 177% in terms of code coverage and discovers 30x more bugs than the second-best fuzzer for non-relational DBMSs, while achieving comparable results with specialized SQL fuzzers for the relational counterpart.

OnlyFans is a subscription-based social media platform with over 1.5 million content creators and 150 million users worldwide. OnlyFans creators primarily produce intimate content for sale on the platform. As such, they are distinctly positioned as content creators and sex workers. Through a qualitative interview study with OnlyFans creators (n=43), building on an existing framework of online hate and harassment, we shed light on the nuanced threats they face and their safety practices. Additionally, we examine the impact of factors such as stigma, prominence, and platform policies on shaping the threat landscape for OnlyFans creators and detail the preemptive practices they undertake to protect themselves. Leveraging these results, we synthesize opportunities to address the challenges of sexual content creators.

Modern microcontrollers (MCU)s are ubiquitous on critical embedded applications in the IoT era. Therefore, securing MCU firmware is fundamental. To analyze MCU firmware security, existing works mostly adopt re-hosting based techniques. These techniques transplant firmware to an engineered platform and require tailored hardware or emulation of different parts of the MCU. As a result, security practitioners have observed low-fidelity, false positives, and reduced compatibility with real and complex hardware. This paper presents SHiFT, a framework that leverages the industry semihosting philosophy to provide a brandnew method that analyzes firmware natively in MCUs. This novel method provides high fidelity, reduces false positives, and grants compatibility with complex peripherals, asynchronous events, real-time operations, and direct memory access (DMA). We verified compatibility of SHiFT with thirteen popular embedded architectures, and fully evaluated prototypes for ARMv7-M, ARMv8-M and Xtensa architectures. Our evaluation shows that SHiFT can detect a wide range of firmware faults with instrumentation running natively in the MCU. In terms of performance, SHiFT is up to two orders of magnitude faster (i.e., ×100) than software-based emulation, and even comparable to fuzz testing native applications in a workstation. Thanks to SHiFT's unique characteristics, we discovered five previously unknown vulnerabilities, including a zero-day on the popular FreeRTOS kernel, with no false positives. Our prototypes and source code are publicly available at https://github.com/RiS3-Lab/SHiFT.

Browser-based cross-platform applications have become increasingly popular as they allow software vendors to sidestep two major issues in the app ecosystem. First, web apps can be impacted by the performance deterioration affecting browsers, as the continuous adoption of diverse and complex features has led to bloating. Second, re-developing or porting apps to different operating systems and execution environments is a costly, error-prone process. Instead, frameworks like Electron allow the creation of standalone apps for different platforms using JavaScript code (e.g., reused from an existing web app) and by incorporating a stripped down and configurable browser engine. Despite the aforementioned advantages, these apps face significant security and privacy threats that are either non-applicable to traditional web apps (due to the lack of access to certain system-facing APIs) or ineffective against them (due to countermeasures already baked into browsers). In this paper we present Inspectron, an automated dynamic analysis framework that audits packaged Electron apps for potential security vulnerabilities stemming from developers' deviation from recommended security practices. Our study reveals a multitude of insecure practices and problematic trends in the Electron app ecosystem, highlighting the gap filled by Inspectron as it provides extensive and comprehensive auditing capabilities for developers and researchers.

Wireless charging is becoming an increasingly popular charging solution in portable electronic products for a more convenient and safer charging experience than conventional wired charging. However, our research identified new vulnerabilities in wireless charging systems, making them susceptible to intentional electromagnetic interference. These vulnerabilities facilitate a set of novel attack vectors, enabling adversaries to manipulate the charger and perform a series of attacks.

In this paper, we propose VoltSchemer, a set of innovative attacks that grant attackers control over commercial-off-the-shelf wireless chargers merely by modulating the voltage from the power supply. These attacks represent the first of its kind, exploiting voltage noises from the power supply to manipulate wireless chargers without necessitating any malicious modifications to the chargers themselves. The significant threats imposed by VoltSchemer are substantiated by three practical attacks, where a charger can be manipulated to: control voice assistants via inaudible voice commands, damage devices being charged through overcharging or overheating, and bypass Qi-standard specified foreign-object-detection mechanism to damage valuable items exposed to intense magnetic fields.

We demonstrate the effectiveness and practicality of the VoltSchemer attacks with successful attacks on 9 top-selling COTS wireless chargers. Furthermore, we discuss the security implications of our findings and suggest possible countermeasures to mitigate potential threats.

Augmented Reality (AR) can enable shared virtual experiences between multiple users. In order to do so, it is crucial for multi-user AR applications to establish a consensus on the "shared state" of the virtual world and its augmentations through which users interact. Current methods to create and access shared state collect sensor data from devices (e.g., camera images), process them, and integrate them into the shared state. However, this process introduces new vulnerabilities and opportunities for attacks. Maliciously writing false data to "poison" the shared state is a major concern for the security of the downstream victims that depend on it. Another type of vulnerability arises when reading the shared state: by providing false inputs, an attacker can view hologram augmentations at locations they are not allowed to access. In this work, we demonstrate a series of novel attacks on multiple AR frameworks with shared states, focusing on three publicly accessible frameworks. We show that these frameworks, while using different underlying implementations, scopes, and mechanisms to read from and write to the shared state, have shared vulnerability to a unified threat model. Our evaluations of these state-of-the-art AR frameworks demonstrate reliable attacks both on updating and accessing the shared state across different systems. To defend against such threats, we discuss a number of potential mitigation strategies that can help enhance the security of multi-user AR applications and implement an initial prototype.

Asymmetric Searchable Encryption (ASE) is a promising cryptographic mechanism that enables a semi-trusted cloud server to perform keyword searches over encrypted data for users. To be useful, an ASE scheme must support expressive search queries, which are expressed as conjunction, disjunction, or any Boolean formulas. In this paper, we propose a fast and expressive ASE scheme that is adaptively secure, called FEASE. It requires only 3 pairing operations for searching any conjunctive set of keywords independent of the set size and has linear complexity for encryption and trapdoor algorithms in the number of keywords. FEASE is based on a new fast Anonymous Key-Policy Attribute-Based Encryption (A-KP-ABE) scheme as our first proposal, which is of independent interest. To address optional protection against keyword guessing attacks, we extend FEASE into the first expressive Public-Key Authenticated Encryption with Keyword Search (PAEKS) scheme. We provide implementations and evaluate the performance of all three schemes, while also comparing them with the state of the art. We observe that FEASE outperforms all existing expressive ASE constructions and that our A-KP-ABE scheme offers anonymity with efficiency comparable to the currently fastest yet non-anonymous KP-ABE schemes FAME (ACM CCS 2017) and FABEO (ACM CCS 2022).

This paper presents a novel attack technique called page-oriented programming, which reuses existing code gadgets by remapping physical pages to the virtual address space of a program at runtime. The page remapping vulnerabilities may lead to data breaches or may damage kernel integrity. Therefore, manufacturers have recently released products equipped with hardware-assisted guest kernel integrity enforcement. This paper extends the notion of the page remapping attack to another type of code-reuse attack, which can not only be used for altering or sniffing kernel data but also for building and executing malicious code at runtime. We demonstrate the effectiveness of this attack on state-of-the-art hardware and software, where control-flow integrity policies are enforced, thus highlighting its capability to render most legacy systems vulnerable.

Researchers are increasingly exploring how gender, culture, and other sociodemographic factors correlate with user computer security and privacy behaviors. To more holistically understand relationships between these factors and behaviors, we make two contributions. First, we broadly survey existing scholarship on sociodemographics and secure behavior (151 papers) before conducting a focused literature review of 47 papers to synthesize what is currently known and identify open questions for future research. Second, by incorporating contemporary social and critical theories, we establish guidelines for future studies of sociodemographic factors and security behaviors that address how to overcome common pitfalls. We present a case study to demonstrate our guidelines in action, at-scale, that conduct a measurement study of the relationships between sociodemographics and de-identified, aggregated log data of security and privacy behaviors among 16,829 users on Facebook across 16 countries. Through these contributions, we position our work as a systemization of a lack of knowledge (SoLK). Overall, we find contradictory results and vast unknowns about how identity shapes security behavior. Through our guidelines and discussion, we chart new directions to more deeply examine how and why sociodemographic factors affect security behaviors.

Content creators are exposed to elevated risks compared to the general Internet user. This study explores the threat landscape that creators in Pakistan are exposed to, how they protect themselves, and which support structures they rely on. We conducted a semi-structured interview study with 23 creators from diverse backgrounds who create content on various topics. Our data suggests that online threats frequently spill over into the offline world, especially for gender minorities. Creating content on sensitive topics like politics, religion, and human rights is associated with elevated risks. We find that defensive mechanisms and external support structures are non-existent, lacking, or inadequately adjusted to the sociocultural context of Pakistan.

Disclaimer: This paper contains quotes describing harmful experiences relating to sexual and physical assault, eating disorders, and extreme threats of violence.

Recently, deep learning has demonstrated promising results in enhancing the accuracy of vulnerability detection and identifying vulnerabilities in software. However, these techniques are still vulnerable to attacks. Adversarial examples can exploit vulnerabilities within deep neural networks, posing a significant threat to system security. This study showcases the susceptibility of deep learning models to adversarial attacks, which can achieve 100% attack success rate. The proposed method, EaTVul, encompasses six stages: identification of important adversarial samples using support vector machines, identification of important features using the attention mechanism, generation of adversarial data based on these features, preparation of an adversarial attack pool, selection of seed data using a fuzzy genetic algorithm, and the execution of an evasion attack. Extensive experiments demonstrate the effectiveness of EaTVul, achieving an attack success rate of more than 83% when the snippet size is greater than 2. Furthermore, in most cases with a snippet size of 4, EaTVul achieves a 100% attack success rate. The findings of this research emphasize the necessity of robust defenses against adversarial attacks in software vulnerability detection.

Machine Learning as a Service (MLaaS) is an increasingly popular design where a company with abundant computing resources trains a deep neural network and offers query access for tasks like image classification. The challenge with this design is that MLaaS requires the client to reveal their potentially sensitive queries to the company hosting the model. Multi-party computation (MPC) protects the client's data by allowing encrypted inferences. However, current approaches suffer from prohibitively large inference times. The inference time bottleneck in MPC is the evaluation of non-linear layers such as ReLU activation functions. Motivated by the success of previous work co-designing machine learning and MPC, we develop an activation function co-design. We replace all ReLUs with a polynomial approximation and evaluate them with single-round MPC protocols, which give state-of-theart inference times in wide-area networks. Furthermore, to address the accuracy issues previously encountered with polynomial activations, we propose a novel training algorithm that gives accuracy competitive with plaintext models. Our evaluation shows between 3 and 110× speedups in inference time on large models with up to 23 million parameters while maintaining competitive inference accuracy.

Searchable symmetric encryption schemes often unintentionally disclose certain sensitive information, such as access, volume, and search patterns. Attackers can exploit such leakages and other available knowledge related to the user's database to recover queries. We find that the effectiveness of query recovery attacks depends on the volume/frequency distribution of keywords. Queries containing keywords with high volumes/frequencies are more susceptible to recovery, even when countermeasures are implemented. Attackers can also effectively leverage these "special" queries to recover all others.

By exploiting the above finding, we propose a Jigsaw attack that begins by accurately identifying and recovering those distinctive queries. Leveraging the volume, frequency, and cooccurrence information, our attack achieves 90% accuracy in three tested datasets, which is comparable to previous attacks (Oya et al., USENIX' 22 and Damie et al., USENIX' 21). With the same runtime, our attack demonstrates an advantage over the attack proposed by Oya et al (approximately 15% more accuracy when the keyword universe size is 15k). Furthermore, our proposed attack outperforms existing attacks against widely studied countermeasures, achieving roughly 60% and 85% accuracy against the padding and the obfuscation, respectively. In this context, with a large keyword universe (≥3k), it surpasses current state-of-the-art attacks by more than 20%.

Data minimization is a legal and privacy-by-design principle mandating that online services collect only data that is necessary for pre-specified purposes. While the principle has thus far mostly been interpreted from a system-centered perspective, there is a lack of understanding about how data minimization could be designed from a user-centered perspective, and in particular, what factors might influence user decision-making with regard to the necessity of data for different processing purposes. To address this gap, in this paper, we gain a deeper understanding of users' design expectations and decision-making processes related to data minimization, focusing on a case study of search engines. We also elicit expert evaluations of the feasibility of user-generated design ideas. We conducted interviews with 25 end users and 10 experts from the EU and UK to provide concrete design recommendations for data minimization that incorporate user needs, concerns, and preferences. Our study (i) surfaces how users reason about the necessity of data in the context of search result quality, and (ii) examines the impact of several factors on user decision-making about data processing, including specific types of search data, or the volume and recency of data. Most participants emphasized the particular importance of data minimization in the context of sensitive searches, such as political, financial, or health-related search queries. In a think-aloud conceptual design session, participants recommended search profile customization as a solution for retaining data they considered necessary, as well as alert systems that would inform users to minimize data in instances of excessive collection. We propose actionable design features that could provide users with greater agency over their data through user-controlled data minimization, combined with relevant implementation insights from experts.

Online learning is widely used in production to refine model parameters after initial deployment. This opens several vectors for covertly launching attacks against deployed models. To detect these attacks, prior work developed black-box and white-box testing methods. However, this has left prohibitive open challenge: how the investigator is supposed to recover the model (uniquely refined on an in-the-field device) for testing in the first place. We propose a novel memory forensic technique, named AiP, which automatically recovers the unique deployment model and rehosts it in a lab environment for investigation. AiP navigates through both main memory and GPU memory spaces to recover complex ML data structures, using recovered Python objects to guide the recovery of lower-level C objects, ultimately leading to the recovery of the uniquely refined model. AiP then rehosts the model within the investigator's device, where the investigator can apply various white-box testing methodologies. We have evaluated AiP using three versions of TensorFlow and PyTorch with the CIFAR-10, LISA, and IMDB datasets. AiP recovered 30 models from main memory and GPU memory with 100% accuracy and rehosted them into a live process successfully.

Efforts from emerging technology companies aim to democratize the ad delivery ecosystem and build systems that are privacy-centric and even share ad revenue benefits with their users. Other providers offer remuneration for users on their platform for interacting with and making use of services. But these efforts may suffer from coordinated abuse efforts aiming to defraud them. Attackers can use VPNs and proxies to fabricate their geolocation and earn disproportionate rewards. Balancing proxy-enabled abuse-prevention techniques with a privacy-focused business model is a hard challenge. Can service providers use minimal connection features to infer proxy use without jeopardizing user privacy?

In this paper, we build and evaluate a solution, CalcuLatency, that incorporates various network latency measurement techniques and leverage the application-layer and network-layer differences in roundtrip-times when a user connects to the service using a proxy. We evaluate our four measurement techniques individually, and as an integrated system using a two-pronged evaluation. CalcuLatency is an easy-to-deploy, open-source solution that can serve as an inexpensive first-step to label proxies.

LiDAR-based perception is crucial to ensure the safety and reliability of autonomous driving (AD) systems. Though some adversarial attack methods against LiDAR-based detectors perception models have been proposed, deceiving such models in the physical world is still challenging. While existing robustness methods focus on transforming point clouds to embed more robust adversarial information, our research reveals how to reduce the errors during the LiDAR capturing process to improve the robustness of adversarial attacks. In this paper, we present AE-Morpher, a novel approach that minimizes differences between the LiDAR-captured and original adversarial point clouds to improve the robustness of adversarial objects. It reconstructs the adversarial object using surfaces with regular shapes to fit the discrete laser beams. We evaluate AE-Morpher by conducting physical disappearance attacks that use a mounted adversarial ornament to conceal a car from models' detection results in both SVL Simulator environments and real-world LiDAR setups. In the simulated world, we successfully deceive the model up to 91.1% of the time when LiDAR moves towards the target vehicle from 20m away. On average, our method increases the ASR by 38.64% and reduces the adversarial ornament's projection area by 67.59%. For the real world, we achieve an average attack success rate of 71.4% over a 12m motion scenario. Moreover, adversarial objects reconstructed by our method can be easily physically constructed by human hands without the requirement of a 3D printer.

Type confusion occurs when C or C++ code accesses an object after casting it to an incompatible type. The security impacts of type confusion vulnerabilities are significant, potentially leading to system crashes or even arbitrary code execution. To mitigate these security threats, both static and dynamic approaches have been developed to detect type confusion bugs. However, static approaches can suffer from excessive false positives, while existing dynamic approaches track type information for each object to enable safety checking at each cast, introducing a high runtime overhead.

In this paper, we present a novel tool T-PRUNIFY to reduce the overhead of dynamic type confusion sanitizers. We observe that in large complex C++ projects, to prevent type confusion bugs, developers often add their own encoding of runtime type information (RTTI) into classes, to enable efficient runtime type checks before casts. T-PRUNIFY works by first identifying these custom RTTI in classes, automatically determining the relationship between field and method return values and the concrete types of corresponding objects. Based on these custom RTTI, T-PRUNIFY can identify cases where a cast is protected by developer-written type checks that guarantee the safety of the cast. Consequently, it can safely remove sanitizer instrumentation for such casts, reducing performance overhead. We evaluate T-PRUNIFY based on HexType, a state-of-the-art type confusion sanitizer that supports extensive C++ projects such as Google Chrome. Our findings demonstrate that our method significantly lowers HexType's average overhead by 25% to 75% in large C++ programs, marking a substantial enhancement in performance.

In this paper, we present the first contactless side-channel attack for identifying 360° videos being viewed in a Virtual Reality (VR) Head Mounted Display (HMD). Although the video content is displayed inside the HMD without any external exposure, we observe that user head movements are driven by the video content, which creates a unique side channel that does not exist in traditional 2D videos. By recording the user whose vision is blocked by the HMD via a malicious camera, an attacker can analyze the correlation between the user's head movements and the victim video to infer the video title.

To exploit this new vulnerability, we present INTRUDE, a system for identifying 360° videos from recordings of user head movements. INTRUDE is empowered by an HMD-based head movement estimation scheme to extract a head movement trace from the recording and a video saliency-based trace-fingerprint matching framework to infer the video title. Evaluation results show that INTRUDE achieves over 96% of accuracy for video identification and is robust under different recording environments. Moreover, INTRUDE maintains its effectiveness in the open-world identification scenario.

Rapid embedded device proliferation is creating new targets and opportunities for adversaries. However, the complex interactions between firmware and hardware pose challenges to applying automated testing, such as fuzzing. State-of-the-art methods re-host firmware in emulators and facilitate complex interactions with hardware by provisioning for inputs from a diversity of methods (such as interrupts) from a plethora of devices (such as modems). We recognize a significant disconnect between how a fuzzer generates inputs (as a monolithic file) and how the inputs are consumed during re-hosted execution (as a stream, in slices, per peripheral). We demonstrate the disconnect to significantly impact a fuzzer's effectiveness at discovering inputs that explore deeper code and bugs.

We rethink the input generation process for fuzzing monolithic firmware and propose a new approach—multi-stream input generation and representation; inputs are now a collection of independent streams, one for each peripheral. We demonstrate the versatility and effectiveness of our approach by implementing: i) stream specific mutation strategies; ii) efficient methods for generating useful values for peripherals; iii) enhancing the use of information learned during fuzzing; and iv) improving a fuzzer's ability to handle roadblocks. We design and build a new fuzzer, MULTIFUZZ, for testing monolithic firmware and evaluate our approach on synthetic and real-world targets. MULTIFUZZ passes all 66 unit tests from a benchmark consisting of 46 synthetic binaries targeting a diverse set of microcontrollers. On an evaluation with 23 real-world firmware targets, MULTIFUZZ outperforms the state-of-the-art fuzzers Fuzzware and Ember-IO. MULTIFUZZ reaches significantly more code on 14 out of the 23 firmware targets and similar coverage on the remainder. Further, MULTIFUZZ discovered 18 new bugs on real-world targets, many thoroughly tested by previous fuzzers.

Federated Learning (FL) trains a black-box and high-dimensional model among different clients by exchanging parameters instead of direct data sharing, which mitigates the privacy leak incurred by machine learning. However, FL still suffers from membership inference attacks (MIA) or data reconstruction attacks (DRA). In particular, an attacker can extract the information from local datasets by constructing DRA, which cannot be effectively throttled by existing techniques, e.g., Differential Privacy (DP).

In this paper, we aim to ensure a strong privacy guarantee for FL under DRA. We prove that econstruction errors under DRA are constrained by the information acquired by an attacker, which means that constraining the transmitted information can effectively throttle DRA. To quantify the information leakage incurred by FL, we establish a channel model, which depends on the upper bound of joint mutual information between the local dataset and multiple transmitted parameters. Moreover, the channel model indicates that the transmitted information can be constrained through data space operation, which can improve training efficiency and the model accuracy under constrained information. According to the channel model, we propose algorithms to constrain the information transmitted in a single round of local training. With a limited number of training rounds, the algorithms ensure that the total amount of transmitted information is limited. Furthermore, our channel model can be applied to various privacy-enhancing techniques (such as DP) to enhance privacy guarantees against DRA. Extensive experiments with real-world datasets validate the effectiveness of our methods.

Internet-wide scanning is a critical tool for security researchers and practitioners alike. By exhaustively exploring the entire IPv4 address space, Internet scanning has driven the development of new security protocols, found and tracked vulnerabilities, improved DDoS defenses, and illuminated global censorship. Unfortunately, the vast scale of the IPv6 address space—340 trillion trillion trillion addresses—precludes exhaustive scanning, necessitating entirely new IPv6-specific scanning methods. As IPv6 adoption continues to grow, developing IPv6 scanning methods is vital for maintaining our capability to comprehensively investigate Internet security.

We present 6SENSE, an end-to-end Internet-wide IPv6 scanning system. 6SENSE utilizes reinforcement learning coupled with an online scanner to iteratively reduce the space of possible IPv6 addresses into a tractable scannable subspace, thus discovering new IPv6 Internet hosts. 6SENSE is driven by a set of metrics we identify and define as key for evaluating the generality, diversity, and correctness of IPv6 scanning. We evaluate 6SENSE and prior generative IPv6 discovery methods across these metrics, showing that 6SENSE is able to identify tens of millions of IPv6 hosts, which compared to prior approaches, is up to 3.6x more hosts and 4x more end-site assignments, across a more diverse set of networks. From our analysis, we identify limitations in prior generative approaches that preclude their use for Internet-scale security scans. We also conduct the first Internet-wide scanning-driven security analysis of IPv6 hosts, focusing on TLS certificates unique to IPv6, surveying open ports and security-sensitive services, and identifying potential CVEs.

A type of traffic analysis, website fingerprinting (WFP), aims to reveal the website a user visits over an encrypted and anonymized connection by observing and analyzing data flow patterns. Its efficiency against anonymization networks such as Tor has been widely studied, resulting in methods that have steadily increased in both complexity and power. While modern WFP attacks have proven to be highly accurate in laboratory settings, their real-world feasibility is highly debated. These attacks also exclude valuable information by ignoring typical user browsing behavior: users often visit multiple pages of a single website sequentially, e.g., by following links.

In this paper, we aim to provide a more realistic assessment of the degree to which Tor users are exposed to WFP. We propose both a novel WFP attack and efficient strategies for adapting existing methods to account for sequential visits of pages within a website. While existing WFP attacks fail to detect almost any website in real-world settings, our novel methods achieve F1-scores of 1.0 for more than half of the target websites. Our attacks remain robust against state-of-the-art WFP defenses, achieving 2.5 to 5 times the accuracy of prior work, and in some cases even rendering the defenses useless. Our methods enable to estimate and to communicate to the user the risk of successive page visits within a website (even in the presence of noise pages) to stop before the WFP attack reaches a critical level of confidence.

Most existing targeted password guessing models view users' reuse behaviors as sequences of edit operations (e.g., insert and delete) performed on old passwords. These atomic edit operations are limited to modifying one character at a time and cannot fully cover users' complex password modification behaviors (e.g., modifying the password structure). This partially leads to a significant gap between the proportion of users' reused passwords and the success rates that existing targeted password models can achieve. To fill this gap, this paper models users' reuse behaviors by focusing on two key components: (1) What they want to copy/keep; (2) What they want to tweak. More specifically, we introduce the pointer mechanism and propose a new targeted guessing model, namely PointerGuess. By hierarchically redefining password reuse from both personal and population-wide perspectives, we can accurately and comprehensively characterize users' password reuse behaviors. Moreover, we propose MS-PointerGuess, which can employ the victim's multiple leaked passwords.

By employing 13 large-scale real-world password datasets, we demonstrate that PointerGuess is effective: (1) When the victim's password at site A (namely pwA) is known, within 100 guesses, the average success rate of PointerGuess in guessing her password at site B (namely pwB, pwA ≠ pwB) is 25.21% (for common users) and 12.34% (for security-savvy users), respectively, which is 21.23%~71.54% (38.37% on average) higher than its foremost counterparts; (2) When not excluding identical password pairs (i.e., pwA can equal pwB), within 100 guesses, the average success rate of PointerGuess is 48.30% (for common users) and 28.42% (for security-savvy users), respectively, which is 6.31%~15.92% higher than its foremost counterparts; (3) Within 100 guesses, the MS-PointerGuess further improves the cracking success rate by 31.21% compared to PointerGuess.

Succinct Non-interactive Arguments of Knowledge (SNARKs) have seen interest and development from the cryptographic community over recent years, and there are now constructions with very small proof size designed to work well in practice. A SNARK protocol can only be widely accepted as secure, however, if a rigorous proof of its security properties has been vetted by the community. Even then, it is sometimes the case that these security proofs are flawed, and it is then necessary for further research to identify these flaws and correct the record.

To increase the rigor of these proofs, we create a formal framework in the Lean theorem prover for representing a widespread subclass of SNARKs based on linear PCPs. We then describe a decision procedure for checking the soundness of SNARKs in this class. We program this procedure and use it to formalize the soundness proof of several different SNARK constructions, including the well-known Groth '16.

Object Detection (OD) and Object Tracking (OT) are an important part of autonomous systems (AS), enabling them to perceive and reason about their surroundings. While both OD and OT have been successfully attacked, defenses only exist for OD. In this paper, we introduce VOGUES, which combines perception algorithms in AS with logical reasoning about object components to model human perception. VOGUES leverages pose estimation algorithms to reconstruct the constituent components of objects within a scene, which are then mapped via bipartite matching against OD/OT predictions to detect OT attacks. VOGUES's component reconstruction process is designed such that attacks against OD/OT will not implicitly affect its performance. To prevent adaptive attackers from simultaneously evading OD/OT and component reconstruction, VOGUES integrates an LSTM validator to ensure that the component behavior of objects remains consistent over time. Evaluations in both the physical domain and digital domain yield an average attack detection rate of 96.78% and an FPR of 3.29%. Meanwhile, adaptive attacks against VOGUES require perturbations 30x stronger than previously established in OT attack works, significantly increasing the attack difficulty and reducing their practicality.

The SSH protocol provides secure access to network services, particularly remote terminal login and file transfer within organizational networks and to over 15 million servers on the open internet. SSH uses an authenticated key exchange to establish a secure channel between a client and a server, which protects the confidentiality and integrity of messages sent in either direction. The secure channel prevents message manipulation, replay, insertion, deletion, and reordering. At the network level, SSH uses the Binary Packet Protocol over TCP.

In this paper, we show that as new encryption algorithms and mitigations were added to SSH, the SSH Binary Packet Protocol is no longer a secure channel: SSH channel integrity (INT-PST, aINT-PTXT, and INT-sfCTF) is broken for three widely used encryption modes. This allows prefix truncation attacks where encrypted packets at the beginning of the SSH channel can be deleted without the client or server noticing it. We demonstrate several real-world applications of this attack. We show that we can fully break SSH extension negotiation (RFC 8308), such that an attacker can downgrade the public key algorithms for user authentication or turn off a new countermeasure against keystroke timing attacks introduced in OpenSSH 9.5. Further, we identify an implementation flaw in AsyncSSH that, together with prefix truncation, allows an attacker to redirect the victim's login into a shell controlled by the attacker.

We also performed an internet-wide scan for affected encryption modes and support for extension negotiation. We find that 71.6% of SSH servers support a vulnerable encryption mode, while 63.2% even list it as their preferred choice.

We identify two root causes that enable these attacks: First, the SSH handshake supports optional messages that are not authenticated. Second, SSH does not reset message sequence numbers when activating encryption keys. Based on this analysis, we propose effective and backward-compatible changes to SSH that mitigate our attacks.

Privacy violations and compliance issues in mobile apps are serious concerns for users, developers, and regulators. With many off-the-shelf tools on Android, prior works extensively studied various privacy issues for Android apps. Privacy risks and compliance issues can be equally expected in iOS apps, but have been little studied. In particular, a prominent recent privacy concern was due to diverse third-party libraries widely integrated into mobile apps whose privacy practices are non-transparent. Such a critical supply chain problem, however, was never systematically studied for iOS apps, at least partially due to the lack of the necessary tools.

This paper presents the first large-scale study, based on our new taint analysis system named iHunter, to analyze privacy violations in the iOS software supply chain. iHunter performs static taint analysis on iOS SDKs to extract taint traces representing privacy data collection and leakage practices. It is characterized by an innovative iOS-oriented symbolic execution that tackles dynamic features of Objective-C and Swift and an NLP-powered generator for taint sources and taint rules. iHunter identified non-compliance in 2,585 SDKs (accounting for 40.4%) out of 6,401 iOS SDKs, signifying a substantial presence of SDKs that fail to adhere to compliance standards. We further found a high proportion (47.2% in 32,478) of popular iOS apps using these SDKs, with practical non-compliance risks violating Apple policies and major privacy laws. These results shed light on the pervasiveness and severity of privacy violations in iOS apps' supply chain. iHunter is thoroughly evaluated for its high effectiveness and efficiency. We are responsibly reporting the results to relevant stakeholders.

Threat modeling is considered an essential first step for "secure by design" development. Significant prior work and industry efforts have created novel methods for this type of threat modeling, and evaluated them in various simulated settings. Because threat modeling is context-specific, we focused on medical device security experts as regulators require it, and "secure by design" medical devices are seen as a critical step to securing healthcare. We conducted 12 semi-structured interviews with medical device security experts, having participants brainstorm threats and mitigations for two medical devices. We saw these experts do not sequentially work through a list of threats or mitigations according to the rigorous processes described in existing methods and, instead, regularly switch strategies. Our work consists of three major contributions. The first is a two-part process model that describes how security experts 1) determine threats and mitigations for a particular component and 2) move between components. Second, we observed participants leveraging use cases, a strategy not addressed in prior work for threat modeling. Third, we found that integrating safety into threat modeling is critical, albeit unclear. We also provide recommendations for future work.

Modern web browsers support rich extension ecosystems that provide users with customized and flexible browsing experiences. Unfortunately, the flexibility of extensions also introduces the potential for abuse, as an extension with sufficient permissions can access and surreptitiously leak sensitive and private browsing data to the extension's authors or third parties. Prior work has explored such extension behavior, but has been limited largely to meta-data about browsing rather than the contents of web pages, and is also based on older versions of browsers, web standards, and APIs, precluding its use for analysis in a modern setting.

In this work, we develop Arcanum, a dynamic taint tracking system for modern Chrome extensions designed to monitor the flow of user content from web pages. Arcanum defines a variety of taint sources and sinks, allowing researchers to taint specific parts of pages at runtime via JavaScript, and works on modern extension APIs, JavaScript APIs, and versions of Chromium. We deploy Arcanum to test all functional extensions currently in the Chrome Web Store for the automated exfiltration of user data across seven sensitive websites: Amazon, Facebook, Gmail, Instagram, LinkedIn, Outlook, and PayPal. We observe significant privacy risks across thousands of extensions, including hundreds of extensions automatically extracting user content from within web pages, impacting millions of users. Our findings demonstrate the importance of user content within web pages, and the need for stricter privacy controls on extensions.

Recently, many works have considered Private Information Retrieval (PIR) with client-preprocessing: In this model a client and a server jointly run a preprocessing phase, after which client queries run in time sublinear in the database size. However, the preprocessing phase is expensive—proportional to λ N, where λ is the security parameter (e.g., λ=128).

In this paper we propose SinglePass, the first PIR protocol that is concretely optimal with respect to client-preprocessing, requiring exactly a single linear pass over the database. Our approach yields a preprocessing speedup ranging from 45× to 100× and a query speedup of up to 20× when compared to previous state-of-the-art schemes (e.g., Checklist, USENIX SECURITY 2021, making preprocessing PIR more attractive for a myriad of use cases that are "session-based".

In addition to practical preprocessing, SinglePass features constant-time updates (additions/edits). Previously, the best known approach for handling updates in client-preprocessing PIR had complexity OlogN, while also adding a logN factor to the bandwidth. We implement our update algorithm and show concrete speedups of about 20× over previous state-of-the-art updatable schemes (e.g., Checklist).

With the growing popularity of modularity in software development comes the rise of package managers and language ecosystems. Among them, npm stands out as the most extensive package manager, hosting more than 2 million third-party open-source packages that greatly simplify the process of building code. However, this openness also brings security risks, as evidenced by numerous package poisoning incidents.

In this paper, we synchronize a local package cache containing more than 3.4 million packages in near real-time to give us access to more package code details. Further, we perform manual inspection and API call sequence analysis on packages collected from public datasets and security reports to build a hierarchical classification framework and behavioral knowledge base covering different sensitive behaviors. In addition, we propose the DONAPI, an automatic malicious npm packages detector that combines static and dynamic analysis. It makes preliminary judgments on the degree of maliciousness of packages by code reconstruction techniques and static analysis, extracts dynamic API call sequences to confirm and identify obfuscated content that static analysis can not handle alone, and finally tags malicious software packages based on the constructed behavior knowledge base. To date, we have identified and manually confirmed 325 malicious samples and discovered 2 unusual API calls and 246 API call sequences that have not appeared in known samples.

Security awareness campaigns in organizations now collectively cost billions of dollars annually. There is increasing focus on ensuring certain security behaviors among employees. On the surface, this would imply a user-centered view of security in organizations. Despite this, the basis of what security awareness managers do and what decides this are unclear. We conducted n=15 semi-structured interviews with full-time security awareness managers, with experience across various national and international companies in European countries, with thousands of employees. Through thematic analysis, we identify that success in awareness management is fragile while having the potential to improve; there are a range of restrictions, and mismatched drivers and goals for security awareness, affecting how it is structured, delivered, measured, and improved. We find that security awareness as a practice is underspecified, and split between messaging around secure behaviors and connecting to employees, with a lack of recognition for the measures that awareness managers regard as important. We discuss ways forward, including alternative indicators of success, and security usability advocacy for employees.

Recent works have identified a gap between research and practice in artificial intelligence security: threats studied in academia do not always reflect the practical use and security risks of AI. For example, while models are often studied in isolation, they form part of larger ML pipelines in practice. Recent works also brought forward that adversarial manipulations introduced by academic attacks are impractical. We take a first step towards describing the full extent of this disparity. To this end, we revisit the threat models of the six most studied attacks in AI security research and match them to AI usage in practice via a survey with 271 industrial practitioners. On the one hand, we find that all existing threat models are indeed applicable. On the other hand, there are significant mismatches: research is often too generous with the attacker, assuming access to information not frequently available in real-world settings. Our paper is thus a call for action to study more practical threat models in artificial intelligence security.

Parents increasingly post content about their children on social media. While such sharing serves beneficial interactive purposes, it can create immediate and longitudinal privacy risks for the children. Studies on parental content sharing have investigated perceptions of parents and children, leaving out those of young adults between the ages of 18 and 30. We addressed this gap via a questionnaire asking young adults about their perspectives on parental sharing of children's photos on social media. We found that young adults who had content about them shared by their parents during childhood and those who were parents expressed greater acceptance of parental sharing practices in terms of motives, content, and audiences. Our findings indicate the need for system features, policies, and digital literacy campaigns to help parents balance the interactive benefits of sharing content about their children and protecting the children's online footprints.

Existing local differential privacy (LDP) techniques enable untrustworthy aggregators to perform only very simple data mining tasks on distributed private data, including statistical estimation and frequent item mining. There is currently no general LDP method that discovers relations between items. The main challenge lies in the curse of dimensionality, as the quantity of values to be estimated in mining relations is the square of the quantity of values to be estimated in mining item-level knowledge, leading to a considerable decrease in the final estimation accuracy. We propose LDP-RM, the first relation mining method under LDP. It represents items and relations in a matrix and utilizes singular value decomposition and low rank approximation to reduce the number of values to estimate from O(k²) to O(r), where k is the number of all considered items, and r < k is a parameter determined by the aggregator, signifying the rank of the approximation. LDP-RM serves as a fundamental privacy-preserving method for enabling various complex data mining tasks.

Race conditions arise when multiple threads attempt to access a shared resource without proper synchronization, often leading to vulnerabilities such as concurrent use-after-free. To mitigate their occurrence, operating systems rely on synchronization primitives such as mutexes, spinlocks, etc.

In this paper, we present GhostRace, the first security analysis of these primitives on speculatively executed code paths. Our key finding is that all the common synchronization primitives can be microarchitecturally bypassed on speculative paths, turning all architecturally race-free critical regions into Speculative Race Conditions (SRCs). To study the severity of SRCs, we focus on Speculative Concurrent Use-After-Free (SCUAF) and uncover 1,283 potentially exploitable gadgets in the Linux kernel. Moreover, we demonstrate that SCUAF information disclosure attacks against the kernel are not only practical, but that their reliability can closely match that of traditional Spectre attacks, with our proof of concept leaking kernel memory at 12 KB/s. Crucially, we develop a new technique to create an unbounded race window, accommodating an arbitrary number of SCUAF invocations required by an end-to-end attack in a single race window. To address the new attack surface, we also propose a generic SRC mitigation to harden all the affected synchronization primitives on Linux. Our mitigation requires minimal kernel changes and incurs only ≈5% geomean performance overhead on LMBench.

"There's security, and then there's just being ridiculous." – Linus Torvalds, on Speculative Race Conditions

Open-source web applications have given everyone the ability to deploy complex web applications on their site(s), ranging from blogs and personal clouds, to server administration tools and webmail clients. Given that there exists millions of deployments of this software in the wild, the ability to fingerprint a particular release of a web application residing at a web endpoint is of interest to both attackers and defenders alike.

In this work, we study modern web application fingerprinting techniques and identify their inherent strengths and weaknesses. We design WASABO, a web application testing framework and use it to measure the performance of six web application fingerprinting tools against 1,360 releases of popular web applications. While 94.8% of all web application releases were correctly labeled by at least one fingerprinting tool in ideal conditions, many tools are unable to produce a single version prediction for a particular release. This leads to instances where a release is labeled as multiple disparate versions, resulting in administrator confusion on the security posture of an unknown web application.

We also measure the accuracy of each tool against real-world deployments of the studied web applications, observing up to an 80% drop-off in performance compared to our offline results. To identify causes for this performance degradation, as well as to improve the robustness of these tools in the wild, we design a web-application-agnostic middleware which applies a series of transformations to the traffic of each fingerprinting tool. Overall, we are able to improve the performance of popular web application fingerprinting tools by up to 22.9%, without any modification to the evaluated tools.

Privacy policies have emerged as the predominant approach to conveying privacy notices to mobile application users. In an effort to enhance both readability and user engagement, the concept of contextual privacy policies (CPPs) has been proposed by researchers. The aim of CPPs is to fragment privacy policies into concise snippets, displaying them only within the corresponding contexts within the application's graphical user interfaces (GUIs). In this paper, we first formulate CPP in mobile application scenario, and then present a novel multimodal framework, named SeePrivacy, specifically designed to automatically generate CPPs for mobile applications. This method uniquely integrates vision-based GUI understanding with privacy policy analysis, achieving 0.88 precision and 0.90 recall to detect contexts, as well as 0.98 precision and 0.96 recall in extracting corresponding policy segments. A human evaluation shows that 77% of the extracted privacy policy segments were perceived as well-aligned with the detected contexts. These findings suggest that SeePrivacy could serve as a significant tool for bolstering user interaction with, and understanding of, privacy policies. Furthermore, our solution has the potential to make privacy notices more accessible and inclusive, thus appealing to a broader demographic. A demonstration of our work can be accessed at: https://cpp4app.github.io/SeePrivacy/

The security guarantees of cloud computing depend on the isolation guarantees of the underlying hypervisors. Prior works have presented effective methods for automatically identifying vulnerabilities in hypervisors. However, these approaches are limited in scope. For instance, their implementation is typically hypervisor-specific and limited by requirements for detailed grammars, access to source-code, and assumptions about hypervisor behaviors. In practice, complex closed-source and recent open-source hypervisors are often not suitable for off-the-shelf fuzzing techniques.

HYPERPILL introduces a generic approach for fuzzing arbitrary hypervisors. HYPERPILL leverages the insight that although hypervisor implementations are diverse, all hypervisors rely on the identical underlying hardware-virtualization interface to manage virtual-machines. To take advantage of the hardware-virtualization interface, HYPERPILL makes a snapshot of the hypervisor, inspects the snapshotted hardware state to enumerate the hypervisor's input-spaces, and leverages feedback-guided snapshot-fuzzing within an emulated environment to identify vulnerabilities in arbitrary hypervisors. In our evaluation, we found that beyond being the first hypervisor-fuzzer capable of identifying vulnerabilities in arbitrary hypervisors across all major attack-surfaces (i.e., PIO/MMIO/Hypercalls/DMA), HYPERPILL also outperforms state-of-the-art approaches that rely on access to source-code, due to the granularity of feedback provided by HYPERPILL's emulation-based approach. In terms of coverage, HYPERPILL outperformed past fuzzers for 10/12 QEMU devices, without the API hooking or source-code instrumentation techniques required by prior works. HYPERPILL identified 26 new bugs in recent versions of QEMU, Hyper-V, and macOS Virtualization Framework across four device-categories

Supporting proofs of evaluations, polynomial commitment schemes (PCS) are crucial in secure distributed systems. Schemes based on fast Reed–Solomon interactive oracle proofs (RS-IOP) of proximity have recently emerged, offering transparent setup, plausible post-quantum security, efficient operations, and, notably, sublinear proof size and verification. Manifesting a new paradigm, PCS with one-to-many proof can enhance the performance of (asynchronous) verifiable secret sharing ((A)VSS), a cornerstone in distributed computing, for proving multiple evaluations to multiple verifiers. Current RS-IOP-based multivariate PCS, including HyperPlonk (Eurocrypt '23) and Virgo (S&P '20), however, only offer quasi-linear prover complexity in the polynomial size.

We propose PolyFRIM, a fast RS-IOP-based multivariate PCS with optimal linear prover complexity, 5-25× faster than prior arts while ensuring competent proof size and verification. Heeding the challenging absence of FFT circuits for multivariate evaluation, PolyFRIM surpasses Zhang et al.'s (Usenix Sec. '22) one-to-many univariate PCS, accelerating proving by 4-7× and verification by 2-4× with 25% shorter proof. Leveraging PolyFRIM, we propose an AVSS scheme FRISS with a better efficiency tradeoff than prior arts from multivariate PCS, including Bingo (Crypto '23) and Haven (FC '21).

Users' growing concerns about online privacy have led to increased platform support for transparency and consent in the web and mobile ecosystems. To that end, Android recently mandated that developers must disclose what user data their applications collect and share, and that information is made available in Google Play's Data Safety section.

In this paper, we provide the first large-scale, in-depth investigation on the veracity of the Data Safety section and its use in the Android application ecosystem. We build an automated analysis framework that dynamically exercises and analyzes applications so as to uncover discrepancies between the applications' behavior and the data practices that have been reported in their Data Safety section. Our study on almost 5K applications uncovers a pervasive trend of incomplete disclosure, as 81% misrepresent their data collection and sharing practices in the Data Safety section. At the same time, 79.4% of the applications with incomplete disclosures do not ask the user to provide consent for the data they collect and share, and 78.6% of those that ask for consent disregard the users' choice. Moreover, while embedded third-party libraries are the most common offender, Data Safety discrepancies can be traced back to the application's core code in 41% of the cases. Crucially, Google's documentation contains various "loopholes" that facilitate incomplete disclosure of data practices. Overall, we find that in its current form, Android's Data Safety section does not effectively achieve its goal of increasing transparency and allowing users to provide informed consent. We argue that Android's Data Safety policies require considerable reform, and automated validation mechanisms like our framework are crucial for ensuring the correctness and completeness of applications' Data Safety disclosures.

Multi-signature schemes have attracted considerable attention in recent years due to their popular applications in PoS blockchains. However, the use of general multi-signature schemes poses a critical threat to the security of PoS blockchains once signing keys get corrupted. That is, after an adversary obtains enough signing keys, it can break the immutable nature of PoS blockchains by forking the chain and modifying the history from some point in the past. Forward-secure multi-signature (FS-MS) schemes can overcome this issue by periodically updating signing keys. The only FS-MS construction currently available is Drijvers et al's Pixel, which builds on pairing groups and only achieves forward security at the time period level.

In this work, we present new FS-MS constructions that either are free from pairing or capture forward security at the individual message level (i.e., fine-grained forward security). Our first construction Pixel+ works for a maximum number of time periods T. Pixel+ signatures consist of only one group element, and can be verified using two exponentiations. It is the first FS-MS from RSA assumption, and has 3.5x and 22.8x faster signing and verification than Pixel, respectively. Our second FS-MS construction Pixel++ is a pairing-based one. It immediately revokes the signing key's capacity of re-signing the message after creating a signature on this message, rather than at the end of the current time period. Thus, it provides more practical forward security than Pixel. On the other hand, Pixel++ is almost as efficient as Pixel in terms of signing and verification. Both Pixel+ and Pixel++ allow for non-interactive aggregation of signatures from independent signers and are proven to be secure in the random oracle model. In addition, they also support the aggregation of public keys, significantly reducing the storage overhead on PoS blockchains.

We demonstrate how to integrate Pixel+ and Pixel++ into PoS blockchains. As a proof-of-concept, we provide implementations of Pixel+ and Pixel++, and conduct several representative experiments to show that Pixel+ and Pixel++ have good concrete efficiency and are practical.

We focus on the problem of I/O-efficient Dynamic Searchable Encryption (DSE), i.e., schemes that perform well when executed with the dataset on-disk. Towards this direction, for HDDs, schemes have been proposed with good locality (i.e., low number of performed non-continuous memory reads) and read efficiency (the number of additional memory locations read per result item). Similarly, for SSDs, schemes with good page efficiency (reading as few pages as possible) have been proposed. However, the vast majority of these works are limited to the static case (i.e. no dataset modifications) and the only dynamic scheme fails to achieve forward and backward privacy, the de-facto leakage standard in the literature. In fact, prior related works (Bost [CCS'16] and Minaud and Reichle[CRYPTO'22]) claim that I/O-efficiency and forward-privacy are two irreconcilable notions. Contrary to that, in this work, we "reconcile" for the first time forward and backward privacy with I/O-efficiency for DSE both for HDDs and SSDs. We propose two families of DSE constructions which also improve the state-of-the-art (non I/O-efficient) both asymptotically and experimentally. Indeed, some of our schemes improve the in-memory performance of prior works. At a technical level, we revisit and enhance the lazy de-amortization DSE construction by Demertzis et al. [NDSS'20], transforming it into an I/O-preserving one. Importantly, we introduce an oblivious-merge protocol that merges two equal-sized databases without revealing any information, effectively replacing the costly oblivious data structures with more lightweight computations.

Warning users about suspicious emails usually happens through visual interventions such as banners. Evidence from laboratory experiments shows that email banner warnings are unsuitable for blind and low-vision (BLV) users as they tend to miss or make no use of them. However, the laboratory settings preclude a full understanding of how BLV users would realistically behave around these banner warnings because the experiments don't use the individuals' own email addresses, devices, or emails of their choice. To address this limitation, we devised a study with n=21 BLV email users in realistic settings. Our findings indicate that this user population misses or makes no use of Gmail and Outlook banner warnings because these are implemented in a "narrow" sense, that is, (i) they allow access to the warning text without providing context relevant to the risk of associated email, and (ii) the formatting, together with the possible actions, is confusing as to how a user should deal with the email in question. To address these barriers, our participants proposed designs to accommodate the accessibility preferences and usability habits of individuals with visual disabilities according to their capabilities to engage with email banner warnings.

Recent developments have underscored the critical role of differential privacy (DP) in safeguarding individual data for training machine learning models. However, integrating DP oftentimes incurs significant model performance degradation due to the perturbation introduced into the training process, presenting a formidable challenge in the differentially private machine learning (DPML) field. To this end, several mitigative efforts have been proposed, typically revolving around formulating new DPML algorithms or relaxing DP definitions to harmonize with distinct contexts. In spite of these initiatives, the diminishment induced by DP on models, particularly large-scale models, remains substantial and thus, necessitates an innovative solution that adeptly circumnavigates the consequential impairment of model utility.

In response, we introduce DPAdapter, a pioneering technique designed to amplify the model performance of DPML algorithms by enhancing parameter robustness. The fundamental intuition behind this strategy is that models with robust parameters are inherently more resistant to the noise introduced by DP, thereby retaining better performance despite the perturbations. DPAdapter modifies and enhances the sharpness-aware minimization (SAM) technique, utilizing a two-batch strategy to provide a more accurate perturbation estimate and an efficient gradient descent, thereby improving parameter robustness against noise. Notably, DPAdapter can act as a plug-and-play component and be combined with existing DPML algorithms to further improve their performance. Our experiments show that DPAdapter vastly enhances state-of-the-art DPML algorithms, increasing average accuracy from 72.92% to 77.09% with a privacy budget of ϵ = 4.

The IETF released RFC 8446 in 2018 as the new TLS 1.3 standard, which recommends using X25519 for key exchange and Ed25519 for identity verification. These computations are the most time-consuming steps in the TLS handshake. Intel introduced AVX-512 in 2013 as an extension of AVX2, and in 2018, AVX-512IFMA, a submodule of AVX-512 to further support 52-bit (integer) multipliers, was implemented on Cannon Lake CPUs.

This paper first revisits various optimization strategies for ECC and presents a more performant X25519/Ed25519 implementation using the AVX-512IFMA instructions. These optimization strategies cover all levels of ECC arithmetic, including finite field arithmetic, point arithmetic, and scalar multiplication computations. Furthermore, we formally verify our finite field implementation to ensure its correctness and robustness.

In addition to the cryptographic implementation, we further explore the deployment of our optimized X25519/Ed25519 library in the TLS protocol layer and the TLS ecosystem. To this end, we design and implement an OpenSSL ENGINE called ENG25519, which propagates the performance benefits of our ECC library to the TLS protocol layer and the TLS ecosystem. The TLS applications can benefit directly from the underlying cryptographic improvements through ENG25519 without necessitating any changes to the source code of OpenSSL and applications. Moreover, we discover that the cold-start issue of vector units degrades the performance of cryptography in TLS protocol, and we develop an auxiliary thread with a heuristic warm-up scheme to mitigate this issue.

Finally, this paper reports a successful integration of the ENG25519 into an unmodified DNS over TLS (DoT) server called unbound, which further highlights the practicality of the ENG25519. We also report benchmarks of TLS 1.3 handshake and DoT query, achieving a speedup of 25% to 35% for TLS 1.3 handshakes per second and an improvement of 24% to 41% for the peak server throughput of DoT queries.

Recovery codes are a popular backup mechanism for online services to aid users who lost their passwords or two-factor authentication tokens in regaining access to their accounts or encrypted data. Especially for end-to-end encrypted services, recovery codes are a critical feature, as the service itself cannot access the encrypted user data and help users regain access. The way end-users manage recovery codes is not well understood. Hence, we investigate end-user perceptions and management strategies of recovery codes. Therefore, we survey users of an end-to-end encrypted email service provider, deploying recovery codes for accounts and encrypted data recovery in case of authentication credential loss. We performed an online survey with 281 users. In a second study, we analyzed 197 support requests on Reddit. Most of our participants stored the service provider's recovery code. We could identify six strategies for saving it, with using a password manager being the most widespread. Participants were generally satisfied with the service provider's recovery code. However, while they appreciated its security, its usability was lacking. We found obstacles, such as losing access to the recovery code or non-functioning recovery codes and security misconceptions. These often resulted from users not understanding the underlying security implications, e.g., that the support cannot access or restore their unencrypted data.

As interest in metadata-hiding communication grows in both research and practice, a need exists for stronger abuse reporting features on metadata-hiding platforms. While message franking has been deployed on major end-to-end encrypted platforms as a lightweight and effective abuse reporting feature, there is no comparable technique for metadata-hiding platforms. Existing efforts to support abuse reporting in this setting, such as asymmetric message franking or the Hecate scheme, require order of magnitude increases in client and server computation or fundamental changes to the architecture of messaging systems. As a result, while metadata-hiding communication inches closer to practice, critical content moderation concerns remain unaddressed.

This paper demonstrates that, for broad classes of metadata-hiding schemes, lightweight abuse reporting can be deployed with minimal changes to the overall architecture of the system. Our insight is that much of the structure needed to support abuse reporting already exists in these schemes. By taking a non-generic approach, we can reuse this structure to achieve abuse reporting with minimal overhead. In particular, we show how to modify schemes based on secret sharing user inputs to support a message franking-style protocol. Compared to prior work, our shared franking technique more than halves the time to prepare a franked message and gives order of magnitude reductions in server-side message processing times, as well as in the time to decrypt a message and verify a report.

Dynamic Searchable Encryption (DSE) has emerged as a solution to efficiently handle and protect large-scale data storage in encrypted databases (EDBs). Volume leakage poses a significant threat, as it enables adversaries to reconstruct search queries and potentially compromise the security and privacy of data. Padding strategies are common countermeasures for the leakage, but they significantly increase storage and communication costs. In this work, we develop a new perspective on handling volume leakage. We start with distinct search and further explore a new concept called distinct DSE (d-DSE).

We also define new security notions, in particular Distinct with Volume-Hiding security, as well as forward and backward privacy, for the new concept. Based on d-DSE, we construct the d-DSE designed EDB with related constructions for distinct keyword (d-KW-dDSE), keyword (KW-dDSE), and join queries (JOIN-dDSE) and update queries in encrypted databases. We instantiate a concrete scheme BF-SRE, employing Symmetric Revocable Encryption. We conduct extensive experiments on real-world datasets, such as Crime, Wikipedia, and Enron, for performance evaluation. The results demonstrate that our scheme is practical in data search and with comparable computational performance to the SOTA DSE scheme (MITRA*, AURA) and padding strategies (SEAL, ShieldDB). Furthermore, our proposal sharply reduces the communication cost as compared to padding strategies, with roughly 6.36 to 53.14x advantage for search queries.

The number and complexity of Trusted Applications (TAs, applications running in Trusted Execution Environments—TEEs) deployed on mobile devices has exploded. A vulnerability in a single TA impacts the security of the entire device. Thus, vendors must rapidly fix such vulnerabilities and revoke vulnerable versions to prevent rollback attacks, i.e., loading an old version of the TA to exploit a known vulnerability.

In this paper, we assess the state of TA rollback prevention by conducting a large-scale cross-vendor study. First, we establish the largest TA dataset in existence, encompassing 35,541 TAs obtained from 1,330 firmware images deployed on mobile devices across the top five most common vendors. Second, we identify 37 TA vulnerabilities that we leverage to assess the state of industry-wide TA rollback effectiveness. Third, we make the counterintuitive discovery that the uncoordinated usage of rollback prevention correlates with the leakage of security-critical information and has far-reaching consequences potentially negatively impacting the whole mobile ecosystem. Fourth, we demonstrate the severity of ineffective TA rollback prevention by exploiting two different TEEs on fully-updated mobile devices. In summary, our results indicate severe deficiencies in TA rollback prevention across the mobile ecosystem.

Cryptography secures our online interactions, transactions, and trust. To achieve this goal, not only do the cryptographic primitives and protocols need to be secure in theory, they also need to be securely implemented by cryptographic library developers in practice.

However, implementing cryptographic algorithms securely is challenging, even for skilled professionals, which can lead to vulnerable implementations, especially to side-channel attacks. For timing attacks, a severe class of side-channel attacks, there exist a multitude of tools that are supposed to help cryptographic library developers assess whether their code is vulnerable to timing attacks. Previous work has established that despite an interest in writing constant-time code, cryptographic library developers do not routinely use these tools due to their general lack of usability. However, the precise factors affecting the usability of these tools remain unexplored. While many of the tools are developed in an academic context, we believe that it is worth exploring the factors that contribute to or hinder their effective use by cryptographic library developers.

To assess what contributes to and detracts from usability of tools that verify constant-timeness (CT), we conducted a two-part usability study with 24 (post) graduate student participants on 6 tools across diverse tasks that approximate real-world use cases for cryptographic library developers.

We find that all studied tools are affected by similar usability issues to varying degrees, with no tool excelling in usability, and usability issues preventing their effective use.

Based on our results, we recommend that effective tools for verifying CT need usable documentation, simple installation, easy to adapt examples, clear output corresponding to CT violations, and minimal noninvasive code markup. We contribute first steps to achieving these with limited academic resources, with our documentation, examples, and installation scripts.

Anonymous message delivery, as in privacy-preserving blockchain and private messaging applications, needs to protect recipient metadata: eavesdroppers should not be able to link messages to their recipients. This raises the question: how can untrusted servers assist in delivering the pertinent messages to each recipient, without learning which messages are addressed to whom?

Recent work constructed Oblivious Message Retrieval (OMR) protocols that outsource the message detection and retrieval in a privacy-preserving way, using homomorphic encryption. Their construction exhibits significant costs in computation per message scanned (∼0.1 second), as well as in the size of the associated messages (∼1kB overhead) and public keys (∼132kB).

This work constructs more efficient OMR schemes, by replacing the LWE-based clue encryption of prior works with a Ring-LWE variant, and utilizing the resulting flexibility to improve several components of the scheme. We thus devise, analyze, and benchmark two protocols:

The first protocol focuses on improving the detector runtime, using a new retrieval circuit that can be homomorphically evaluated 15x faster than the prior work.

The second protocol focuses on reducing the communication costs, by designing a different homomorphic decryption circuit that allows the parameter of the Ring-LWE encryption to be set such that the public key size is about 235x smaller than the prior work, and the message size is roughly 1.6x smaller. The runtime of this second construction is ∼40.0ms per message, still more than 2.5x faster than prior works.

Transport Layer Security (TLS) establishes an authenticated and confidential channel to deliver data for almost all Internet applications. A recent work (Zhang et al., CCS'20) proposed a protocol to prove the TLS payload to a third party, without any modification of TLS servers, while ensuring the privacy and originality of the data in the presence of malicious adversaries. However, it required maliciously secure Two-Party Computation (2PC) for generic circuits, leading to significant computational and communication overhead.

This paper proposes the garble-then-prove technique to achieve the same security requirement without using any heavy mechanism like generic malicious 2PC. Our end-to-end implementation shows 14x improvement in communication and an order of magnitude improvement in computation over the state-of-the-art protocol. We also show worldwide performance when using our protocol to authenticate payload data from Coinbase and Twitter APIs. Finally, we propose an efficient gadget to privately convert the above authenticated TLS payload to additively homomorphic commitments so that the properties of the payload can be proven efficiently using zkSNARKs.

Text-to-Image generation models have revolutionized the artwork design process and enabled anyone to create high-quality images by entering text descriptions called prompts. Creating a high-quality prompt that consists of a subject and several modifiers can be time-consuming and costly. In consequence, a trend of trading high-quality prompts on specialized marketplaces has emerged. In this paper, we perform the first study on understanding the threat of a novel attack, namely prompt stealing attack, which aims to steal prompts from generated images by text-to-image generation models. Successful prompt stealing attacks directly violate the intellectual property of prompt engineers and jeopardize the business model of prompt marketplaces. We first perform a systematic analysis on a dataset collected by ourselves and show that a successful prompt stealing attack should consider a prompt's subject as well as its modifiers. Based on this observation, we propose a simple yet effective prompt stealing attack, PromptStealer. It consists of two modules: a subject generator trained to infer the subject and a modifier detector for identifying the modifiers within the generated image. Experimental results demonstrate that PromptStealer is superior over three baseline methods, both quantitatively and qualitatively. We also make some initial attempts to defend PromptStealer. In general, our study uncovers a new attack vector within the ecosystem established by the popular text-to-image generation models. We hope our results can contribute to understanding and mitigating this emerging threat.

Contactless payments are now widely used and are expected to reach $10 trillion worth of transactions by 2027. Although convenient, contactless payments are vulnerable to relay attacks that enable attackers to execute fraudulent payments. A number of countermeasures have been proposed to address this issue, including Mastercard's relay protection mechanism. These countermeasures, although effective against some Commercial off-the-shelf (COTS) relays, fail to prevent physical-layer relay attacks.

In this work, we leverage the Ultra-Wide Band (UWB) radios incorporated in major smartphones, smartwatches, tags and accessories, and introduce PURE, the first UWB-based relay protection that integrates smoothly into existing contactless payment standards, and prevents even the most sophisticated physical layer attacks. PURE extends EMV payment protocols that are executed between cards and terminals, and does not require any modification to the backend of the issuer, acquirer, or payment network. PURE further tailors UWB ranging to the payment environment (i.e., wireless channels) to achieve both reliability and resistance to all known physical-layer distance reduction attacks against UWB 802.15.4z. We implement PURE within the EMV standard on modern smartphones, and evaluate its performance in a realistic deployment. Our experiments show that PURE provides a sub-meter relay protection with minimal execution overhead (41 ms). We formally verify the security of PURE's integration within Mastercard's EMV protocol using the Tamarin prover.

Circuit-based Private Set Intersection (circuit-PSI) empowers two parties, a client and a server, each with input sets X and Y, to securely compute a function f on the intersection X∩Y while preserving the confidentiality of X∩Y from both parties. Despite the recent proposals of computationally efficient circuit-PSI protocols, they primarily focus on the balanced scenario where |X| is similar to |Y|. However, in many practical situations, a circuit-PSI protocol may be applied in an unbalanced context, where |X| is significantly smaller than |Y|. Directly applying existing protocols to this scenario poses notable efficiency challenges due to the communication complexity of these protocols scaling at least linearly with the size of the larger set, i.e., max(|X|,|Y|).

In this work, we put forth efficient constructions for unbalanced circuit-PSI, demonstrating sublinear communication complexity in the size of the larger set. Our key insight lies in formalizing unbalanced circuit-PSI as the process of obliviously retrieving values corresponding to keys from a set of key-value pairs. To achieve this, we propose a new functionality named Oblivious Key-Value Retrieval (OKVR) and design the OKVR protocol based on a new notion termed sparse Oblivious Key-Value Store (sparse OKVS). We conduct comprehensive experiments and the results showcase substantial improvements over the state-of-the-art circuit-PSI schemes, i.e., 1.84∼48.86x communication improvement and 1.50∼39.81x faster computation. Compared to a very recent unbalanced circuit-PSI work, our constructions outperform them by 1.18∼15.99x and 1.22∼10.44x in communication and computation overhead, respectively, depending on set sizes and network environments.

BusyBox, an open-source software bundling over 300 essential Linux commands into a single executable, is ubiquitous in Linux-based embedded devices. Vulnerabilities in BusyBox can have far-reaching consequences, affecting a wide array of devices. This research, driven by the extensive use of BusyBox, delved into its analysis. The study revealed the prevalence of older BusyBox versions in real-world embedded products, prompting us to conduct fuzz testing on BusyBox. Fuzzing, a pivotal software testing method, aims to induce crashes that are subsequently scrutinized to uncover vulnerabilities. Within this study, we introduce two techniques to fortify software testing. The first technique enhances fuzzing by leveraging Large Language Models (LLM) to generate target-specific initial seeds. Our study showed a substantial increase in crashes when using LLM-generated initial seeds, highlighting the potential of LLM to efficiently tackle the typically labor-intensive task of generating target-specific initial seeds. The second technique involves repurposing previously acquired crash data from similar fuzzed targets before initiating fuzzing on a new target. This approach streamlines the time-consuming fuzz testing process by providing crash data directly to the new target before commencing fuzzing. We successfully identified crashes in the latest BusyBox target without conducting traditional fuzzing, emphasizing the effectiveness of LLM and crash reuse techniques in enhancing software testing and improving vulnerability detection in embedded systems. Additionally, manual triaging was performed to identify the nature of crashes in the latest BusyBox.

Client-side security mechanisms implemented by Web browsers, such as cookie security attributes and the Mixed Content policy, are of paramount importance to protect Web applications. Unfortunately, the design and implementation of such mechanisms are complicated and error-prone, potentially exposing Web applications to security vulnerabilities. In this paper, we present a practical framework to formally and automatically detect security flaws in client-side security mechanisms. In particular, we leverage Web Platform Tests (WPT), a popular cross-browser test suite, to automatically collect browser execution traces and match them against Web invariants, i.e., intended security properties of Web mechanisms expressed in first-order logic. We demonstrate the effectiveness of our approach by validating 9 invariants against the WPT test suite, discovering violations with clear security implications in 104 tests for Firefox, Chromium and Safari. We disclosed the root causes of these violations to browser vendors and standard bodies, which resulted in 8 individual reports and one CVE on Safari.

Distributed key management (DKM) services are multi-party services that allow their users to outsource the generation, storage, and usage of cryptographic private keys, while guaranteeing that none of the involved service providers learn the private keys in the clear. This is typically achieved through distributed key generation (DKG) protocols, where the service providers generate the keys on behalf of the users in an interactive protocol, and each of the servers stores a share of each key as the result. However, with traditional DKM systems, the key material stored by each server grows linearly with the number of users.

An alternative approach to DKM is via distributed key derivation (DKD) where the user key shares are derived on-demand from a constant-size (in the number of users) secret-shared master key and the corresponding user's identity, which is achieved by employing a suitable distributed pseudorandom function (dPRF). However, existing suitable dPRFs require on the order of 100 interaction rounds between the servers and are therefore insufficient for settings with high network latency and where users demand real-time interaction.

To resolve the situation, we initiate the study of lattice-based distributed PRFs, with a particular focus on their application to DKD. Concretely, we show that the LWE-based PRF presented by Boneh et al. at CRYPTO'13 can be turned into a distributed PRF suitable for DKD that runs in only 8 online rounds, which is an improvement over the start-of-the-art by an order of magnitude. We further present optimizations of this basic construction. We show a new construction with improved communication efficiency proven secure under the same "standard" assumptions. Then, we present even more efficient constructions, running in as low as 5 online rounds, from non-standard, new lattice-based assumptions. We support our findings by implementing and evaluating our protocol using the MP-SPDZ framework (Keller, CCS '20). Finally, we give a formal definition of our DKD in the UC framework and prove a generic construction (for which our construction qualifies) secure in this model.

Honeywords are decoy passwords that can be added to a credential database; if a login attempt uses a honeyword, this indicates that the site's credential database has been leaked. In this paper we explore the basic requirements for honeywords to be effective, in a threat model where the attacker knows passwords for the same users at other sites. First, we show that for user-chosen (vs. algorithmically generated, i.e., by a password manager) passwords, existing honeyword-generation algorithms do not simultaneously achieve false-positive and false-negative rates near their ideals of ≈0 and ≈ 1/1+n, respectively, in this threat model, where n is the number of honeywords per account. Second, we show that for users leveraging algorithmically generated passwords, state-of-the-art methods for honeyword generation will produce honeywords that are not sufficiently deceptive, yielding many false negatives. Instead, we find that only a honeyword-generation algorithm that uses the same password generator as the user can provide deceptive honeywords in this case. However, when the defender's ability to infer the generator from the (one) account password is less accurate than the attacker's ability to infer the generator from potentially many, this deception can again wane. Taken together, our results provide a cautionary note for the state of honeyword research and pose new challenges to the field.

Recent privacy laws have strengthened data subjects' right to access personal data collected by companies. Prior work has found that data exports companies provide consumers in response to Data Subject Access Requests (DSARs) can be overwhelming and hard to understand. To identify directions for improving the user experience of data exports, we conducted an online study in which 33 participants explored their own data from Amazon, Facebook, Google, Spotify, or Uber. Participants articulated questions they hoped to answer using the exports. They also annotated parts of the export they found confusing, creepy, interesting, or surprising. While participants hoped to learn either about their own usage of the platform or how the company collects and uses their personal data, these questions were often left unanswered. Participants' annotations documented their excitement at finding data records that triggered nostalgia, but also shock and anger about the privacy implications of other data they saw. Having examining their data, many participants hoped to request the company erase some, but not all, of the data. We discuss opportunities for future transparency-enhancing tools and enhanced laws.

Double-fetch bugs (or vulnerabilities) stem from in-kernel system call execution fetching the same user data twice without proper data (re)sanitization, enabling TOCTTOU attacks and posing a major threat to operating systems security. Existing double-fetch protection systems rely on the MMU to trap on writes to syscall-accessed user pages and provide the kernel with a consistent snapshot of user memory. While this strategy can hinder attacks, it also introduces nontrivial runtime performance overhead due to the cost of trapping/remapping and the coarse (page-granular) write interposition mechanism.

In this paper, we propose SafeFetch, a practical solution to protect the kernel from double-fetch bugs. The key intuition is that most system calls fetch small amounts of user data (if at all), hence caching this data in the kernel can be done at a small performance cost. To this end, SafeFetch creates per-syscall caches to persist fetched user data and replay them when they are fetched again within the same syscall. This strategy neutralizes all double-fetch bugs, while eliminating trapping/remapping overheads and relying on efficient byte-granular interposition. Our Linux prototype evaluation shows SafeFetch can provide comprehensive protection with low performance overheads (e.g., 4.4% geomean on LMBench), significantly outperforming state-of-the-art solutions.

Recent advancements in generative AI have enabled ubiquitous access to large language models (LLMs). Empowered by their exceptional capabilities to understand and generate human-like text, these models are being increasingly integrated into our society. At the same time, there are also concerns on the potential misuse of this powerful technology, prompting defensive measures from service providers. To overcome such protection, jailbreaking prompts have recently emerged as one of the most effective mechanisms to circumvent security restrictions and elicit harmful content originally designed to be prohibited.

Due to the rapid development of LLMs and their ease of access via natural languages, the frontline of jailbreak prompts is largely seen in online forums and among hobbyists. To gain a better understanding of the threat landscape of semantically meaningful jailbreak prompts, we systemized existing prompts and measured their jailbreak effectiveness empirically. Further, we conducted a user study involving 92 participants with diverse backgrounds to unveil the process of manually creating jailbreak prompts. We observed that users often succeeded in jailbreak prompts generation regardless of their expertise in LLMs. Building on the insights from the user study, we also developed a system using AI as the assistant to automate the process of jailbreak prompt generation.

The rise of IoT (Internet of Things) devices has created a system of convenience, which allows users to control and automate almost everything in their homes. But this increase in convenience comes with increased security risks to the users of IoT devices, partially because IoT firmware is frequently complex, feature-rich, and very vulnerable. Existing solutions for automatically finding taint-style vulnerabilities significantly reduce the number of binaries analyzed to achieve scalability. However, we show that this trade-off results in missing significant numbers of vulnerabilities. In this paper, we propose a new direction: scaling static analysis of firmware binaries so that all binaries can be analyzed for command injection or buffer overflows. To achieve this, we developed MANGODFA, a novel binary data-flow analysis leveraging value analysis and data dependency analysis on binary code. Through key algorithmic optimizations in MANGODFA, our prototype Mango achieves fast analysis without sacrificing precision. On the same dataset used in prior work, Mango analyzed 27× more binaries in a comparable amount of time to the state-of-the-art in Linux-based user-space firmware taint-analysis SaTC. Mango achieved an average per-binary analysis time of 8 minutes compared to 6.56 hours for SaTC. In addition, Mango finds 56 real vulnerabilities that SaTC does not find in a set of seven firmware. We also performed an ablation study demonstrating the performance gains in Mango come from key algorithmic improvements.

When developing security and privacy policy, technical solutions, and research for end users, assumptions about end users' financial means and technology use situations often fail to take users' income status into account. This means that the status quo may marginalize those affected by poverty in security and privacy, and exacerbate inequalities. To enable more equitable security and privacy for all, it is crucial to understand the overall situation of low income users, their security and privacy concerns, perceptions, behaviors, and challenges. In this paper, we report on a semi-structured, in-depth interview study with low income users living in Germany (n=28) which we understand as a case study for the growing number of low income users in global north countries. We find that low income end users may be literate regarding technology use and possess solid basic knowledge about security and privacy, and generally show awareness of security and privacy threats and risks. Despite these resources, we also find that low income users are driven to poor security and privacy practices like using an untrusted cloud due to little storage space, and relying on old, broken, or used hardware. Additionally we find the mindset of a—potentially false—sense of security and privacy because through attacking them, there is "not much to get". Based on our findings, we discuss how the security and privacy community can expand comprehension about diverse end users, increase awareness and design for the specific situation of low income users, and should take more vulnerable groups into account.

Hardware-based Trusted execution environments (TEEs) offer an isolation granularity of virtual machine abstraction. They provide confidential VMs (CVMs) that host security-sensitive code and data. AMD SEV-SNP and Intel TDX enable CVMs and are now available on popular cloud platforms. The untrusted hypervisor in these settings is in control of several resource management and configuration tasks, including interrupts. We present HECKLER, a new attack wherein the hypervisor injects malicious non-timer interrupts to break the confidentiality and integrity of CVMs. Our insight is to use the interrupt handlers that have global effects, such that we can manipulate a CVM's register states to change the data and control flow. With AMD SEV-SNP and Intel TDX, we demonstrate HECKLER on OpenSSH and sudo to bypass authentication. On AMD SEV-SNP we break execution integrity of C, Java, and Julia applications that perform statistical and text analysis. We explain the gaps in current defenses and outline guidelines for future defenses.

Snowflake is a system for circumventing Internet censorship. Its blocking resistance comes from the use of numerous, ultra-light, temporary proxies ("snowflakes"), which accept traffic from censored clients using peer-to-peer WebRTC protocols and forward it to a centralized bridge. The temporary proxies are simple enough to be implemented in JavaScript, in a web page or browser extension, making them much cheaper to run than a traditional proxy or VPN server. The large and changing pool of proxy addresses resists enumeration and blocking by a censor. The system is designed with the assumption that proxies may appear or disappear at any time. Clients discover proxies dynamically using a secure rendezvous protocol. When an in-use proxy goes offline, its client switches to another on the fly, invisibly to upper network layers.

Snowflake has been deployed with success in Tor Browser and Orbot for several years. It has been a significant circumvention tool during high-profile network disruptions, including in Russia in 2021 and Iran in 2022. In this paper, we explain the composition of Snowflake's many parts, give a history of deployment and blocking attempts, and reflect on implications for circumvention generally.

Deep Learning (DL) models have become crucial in digital transformation, thus raising concerns about their intellectual property rights. Different watermarking techniques have been developed to protect Deep Neural Networks (DNNs) from IP infringement, creating a competitive field for DNN watermarking and removal methods. The predominant watermarking schemes use white-box techniques, which involve modifying weights by adding a unique signature to specific DNN layers. On the other hand, existing attacks on white-box watermarking usually require knowledge of the specific deployed watermarking scheme or access to the underlying data for further training and fine-tuning. We propose DeepEclipse, a novel and unified framework designed to remove white-box watermarks. We present obfuscation techniques that significantly differ from the existing white-box watermarking removal schemes. DeepEclipse can evade watermark detection without prior knowledge of the underlying watermarking scheme, additional data, or training and fine-tuning. Our evaluation reveals that DeepEclipse excels in breaking multiple white-box watermarking schemes, reducing watermark detection to random guessing while maintaining a similar model accuracy as the original one. Our framework showcases a promising solution to address the ongoing DNN watermark protection and removal challenges.

Zero-knowledge (ZK) proofs have been recently explored for the integrity of machine learning (ML) inference. However, these protocols suffer from high computational overhead, with the primary bottleneck stemming from the evaluation of non-linear functions. In this paper, we propose the first systematic ZK proof framework for non-linear mathematical functions in ML using the perspective of table lookup. The key challenge is that table lookup cannot be directly applied to non-linear functions in ML since it would suffer from inefficiencies due to the intolerably large table. Therefore, we carefully design several important building blocks, including digital decomposition, comparison, and truncation, such that they can effectively utilize table lookup with a quite small table size while ensuring the soundness of proofs. Based on these building blocks, we implement complex mathematical operations and further construct ZK proofs for current mainstream non-linear functions in ML such as ReLU, sigmoid, and normalization. The extensive experimental evaluation shows that our framework achieves 50∼179× runtime improvement compared to the state-of-the-art work, while maintaining a similar level of communication efficiency.

Machine learning has shown great promise in addressing several critical hardware security problems. In particular, researchers have developed novel graph neural network (GNN)-based techniques for detecting intellectual property (IP) piracy, detecting hardware Trojans (HTs), and reverse engineering circuits, to name a few. These techniques have demonstrated outstanding accuracy and have received much attention in the community. However, since these techniques are used for security applications, it is imperative to evaluate them thoroughly and ensure they are robust and do not compromise the security of integrated circuits.

In this work, we propose AttackGNN, the first red-team attack on GNN-based techniques in hardware security. To this end, we devise a novel reinforcement learning (RL) agent that generates adversarial examples, i.e., circuits, against the GNN-based techniques. We overcome three challenges related to effectiveness, scalability, and generality to devise a potent RL agent. We target five GNN-based techniques for four crucial classes of problems in hardware security: IP piracy, detecting/localizing HTs, reverse engineering, and hardware obfuscation. Through our approach, we craft circuits that fool all GNNs considered in this work. For instance, to evade IP piracy detection, we generate adversarial pirated circuits that fool the GNN-based defense into classifying our crafted circuits as not pirated. For attacking HT localization GNN, our attack generates HT-infested circuits that fool the defense on all tested circuits. We obtain a similar 100% success rate against GNNs for all classes of problems.

Fleeceware, a novel category of malicious subscription apps, is increasingly tricking users into expensive subscriptions, leading to substantial financial consequences. These apps' ambiguous nature, closely resembling legitimate subscription apps, complicates their detection in app markets. To address this, our study aims to devise an automated method, named DARKFLEECE, to identify fleeceware through their prevalent use of dark patterns. By recruiting domain experts, we curated the first-ever fleeceware feature library, based on dark patterns extracted from user interfaces (UI). A unique extraction method, which integrates UI elements, layout, and multifaceted extraction rules, has been developed. DARKFLEECE boasts a detection accuracy of 93.43% on our dataset and utilizes Explainable Artificial Intelligence (XAI) to present user-friendly alerts about potential fleeceware risks. When deployed to assess Google Play's app landscape, DARKFLEECE examined 13,597 apps and identified an alarming 75.21% of 589 subscription apps that displayed different levels of fleeceware, totaling around 5 billion downloads. Our results are consistent with user reviews on Google Play. Our detailed exploration into the implications of our results for ethical app developers, app users, and app market regulators provides crucial insights for different stakeholders. This underscores the need for proactive measures against the rise of fleeceware.

Due to costly efforts during data acquisition and model training, Deep Neural Networks (DNNs) belong to the intellectual property of the model creator. Hence, unauthorized use, theft, or modification may lead to legal repercussions. Existing DNN watermarking methods for ownership proof are often non-intuitive, embed human-invisible marks, require trust in algorithmic assessment that lacks human-understandable attributes, and rely on rigid thresholds, making it susceptible to failure in cases of partial watermark erasure.

This paper introduces ClearStamp, the first DNN watermarking method designed for intuitive human assessment. ClearStamp embeds visible watermarks, enabling human decision-making without rigid value thresholds while allowing technology-assisted evaluations. ClearStamp defines a transposed model architecture allowing to use of the model in a backward fashion to interwove the watermark with the main task within all model parameters. Compared to existing watermarking methods, ClearStamp produces visual watermarks that are easy for humans to understand without requiring complex verification algorithms or strict thresholds. The watermark is embedded within all model parameters and entangled with the main task, exhibiting superior robustness. It shows an 8,544-bit watermark capacity comparable to the strongest existing work. Crucially, ClearStamp's effectiveness is model and dataset-agnostic, and resilient against adversarial model manipulations, as demonstrated in a comprehensive study performed with four datasets and seven architectures.