ACM Transactions on Privacy and Security最新文献

Network reconnaissance and measurements play a central role in improving Internet security and are important for understanding the current deployments and trends. Such measurements often require coordination with the measured target. This limits the scalability and the coverage of the existing proposals. IP Identification (IPID) provides a side channel for remote measurements without requiring the targets to install agents or visit the measurement infrastructure. However, current IPID-based techniques have technical limitations due to their reliance on the idealistic assumption of stable IPID changes or prior knowledge, making them challenging to adopt for practical measurements.

In this work, we aim to tackle the limitations of existing techniques by introducing a novel approach: predictive analysis of IPID counter behavior. This involves utilizing a machine learning (ML) model to understand the historical patterns of IPID counter changes and predict future IPID values. To validate our approach, we implement six ML models and evaluate them on realistic IPID data collected from 4,698 Internet sources. Our evaluations demonstrate that among the six models, the GP (Gaussian Process) model has superior accuracy in tracking and predicting IPID values.

Using the GP-based predictive analysis, we implement a tool, called ZPredict, to infer various favorable information about target networks or servers. Our evaluation on a large dataset of public servers demonstrates its effectiveness in idle port scanning, measuring Russian censorship, and inferring Source Address Validation (SAV).

Our study methodology is ethical and was developed to mitigate any potential harm, taking into account the concerns associated with measurements.

Recently, several researchers motivated the need to integrate Zero Trust (ZT) principles when designing and implementing authentication and authorization systems for IoT. An integrated Zero Trust IoT system comprises the network infrastructure (physical and virtual) and operational policies in place for IoT as a product of a ZT architecture plan. This paper proposes a novel Zero Trust architecture for IoT systems called ZTA-IoT. Additionally, based on different types of interactions between various layers and components in this architecture, we present ZTA-IoT-ACF, an access control framework that recognizes different interactions that need to be controlled in IoT systems. Within this framework, the paper then refines its focus to object-level interactions, i.e., interactions where the target resource is a device (equivalently a thing) or an information file generated or stored by a device. Building on the recently proposed Zero Trust score-based authorization framework (ZT-SAF) we develop the object-level Zero Trust score-based authorization framework for IoT systems, denoted as ZTA-IoT-OL-SAF, to govern access requests in this context. With this machinery in place, we finally develop a novel usage control model for users-to-objects and devices-to-objects interactions, denoted as UCON_IoT. We give formal definitions, illustrative use cases, and a proof-of-concept implementation of UCON_IoT. This paper is a first step toward establishing a rigorous formally-defined score-based access control framework for Zero Trust IoT systems.

Remote SIM provisioning (RSP) for consumer devices is the protocol specified by the GSM Association for downloading SIM profiles into a secure element in a mobile device. The process is commonly known as eSIM, and it is expected to replace removable SIM cards. The security of the protocol is critical because the profile includes the credentials with which the mobile device will authenticate to the mobile network. In this paper, we present a formal security analysis of the consumer RSP protocol. We model the multi-party protocol in applied pi calculus, define formal security goals, and verify them in ProVerif. The analysis shows that the consumer RSP protocol protects against a network adversary when all the intended participants are honest. However, we also model the protocol in realistic partial compromise scenarios where the adversary controls a legitimate participant or communication channel. The security failures in the partial compromise scenarios reveal weaknesses in the protocol design. The most important observation is that the security of RSP depends unnecessarily on it being encapsulated in a TLS tunnel. Also, the lack of pre-established identifiers means that a compromised download server anywhere in the world or a compromised secure element can be used for attacks against RSP between honest participants. Additionally, the lack of reliable methods for verifying user intent can lead to serious security failures. Based on the findings, we recommend practical improvements to RSP implementations, future versions of the specification, and mobile operator processes to increase the robustness of eSIM security.

Sound-squatting is a squatting technique that exploits similarities in word pronunciation to trick users into accessing malicious resources. It is an understudied threat that has gained traction with the popularity of smart speakers and audio-only content, such as podcasts. The picture gets even more complex when multiple languages are involved. We here introduce X-squatter, a multi- and cross-language AI-based system that relies on a Transformer Neural Network for generating high-quality sound-squatting candidates. We illustrate the use of X-squatter by searching for domain name squatting abuse across hundreds of millions of issued TLS certificates, alongside other squatting types. Key findings unveil that approximately 15% of generated sound-squatting candidates have associated TLS certificates, well above the prevalence of other squatting types (7%). Furthermore, we employ X-squatter to assess the potential for abuse in PyPI packages, revealing the existence of hundreds of candidates within a three-year package history. Notably, our results suggest that the current platform checks cannot handle sound-squatting attacks, calling for better countermeasures. We believe X-squatter uncovers the usage of multilingual sound-squatting phenomenon on the Internet and it is a crucial asset for proactive protection against the threat.

Automatic speech recognition (ASR) systems are vulnerable to audio adversarial examples, which aim to deceive ASR systems by adding perturbations to benign speech signals. These audio adversarial examples appear indistinguishable from benign audio waves, but the ASR system decodes them as intentional malicious commands. Previous studies have demonstrated the feasibility of such attacks in simulated environments (over-line) and have further showcased the creation of robust physical audio adversarial examples (over-air). Various defense techniques have been proposed to counter these attacks. However, most of them have either failed to handle various types of attacks effectively or have resulted in significant time overhead.

In this paper, we propose a novel method for detecting audio adversarial examples. Our approach involves feeding both smoothed audio and original audio inputs into the ASR system. Subsequently, we introduce noise to the logits before providing them to the decoder of the ASR. We demonstrate that carefully selected noise can considerably influence the transcription results of audio adversarial examples while having minimal impact on the transcription of benign audio waves. Leveraging this characteristic, we detect audio adversarial examples by comparing the altered transcription, resulting from logit noising, with the original transcription. The proposed method can be easily applied to ASR systems without requiring any structural modifications or additional training. Experimental results indicate that the proposed method exhibits robustness against both over-line and over-air audio adversarial examples, outperforming state-of-the-art detection methods.