The protection of cryptographic software implementations against power-analysis attacks is critical for applications in embedded systems. A commonly used algorithmic countermeasure against these attacks is masking, a secret-sharing scheme that splits a sensitive computation into computations on multiple random shares. In practice, the security of masking schemes relies on several assumptions that are often violated by microarchitectural side-effects of CPUs. Many past works address this problem by studying these leakage effects and building corresponding leakage models that can then be integrated into a software verification workflow. However, these models have only been derived empirically, putting in question the otherwise rigorous security statements made with verification. We solve this problem in two steps. First, we introduce a contract layer between the (CPU) hardware and the software that allows the specification of microarchitectural side-effects on masked software in an intuitive language. Second, we present a method for proving the correspondence between contracts and CPU netlists to ensure the completeness of the specified leakage models. Then, any further security proofs only need to happen between software and contract, which brings benefits such as reduced verification runtime, improved user experience, and the possibility of working with vendor-supplied contracts of CPUs whose design is not available on netlist-level due to IP restrictions. We apply our approach to the popular RISC-V IBEX core, provide a corresponding formally verified contract, and describe how this contract could be used to verify masked software implementations.
Plts Physical Layer Test System Cracked
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Real-Time Operating System (RTOS) has become the main category of embedded systems. It is widely used to support tasks requiring real-time response such as printers and switches. The security of RTOS has been long overlooked as it was running in special environments isolated from attackers. However, with the rapid development of IoT devices, tremendous RTOS devices are connected to the public network. Due to the lack of security mechanisms, these devices are extremely vulnerable to a wide spectrum of attacks. Even worse, the monolithic design of RTOS combines various tasks and services into a single binary, which hinders the current program testing and analysis techniques working on RTOS. In this paper, we propose SFuzz, a novel slice-based fuzzer, to detect security vulnerabilities in RTOS. Our insight is that RTOS usually divides a complicated binary into many separated but single-minded tasks. Each task accomplishes a particular event in a deterministic way and its control flow is usually straightforward and independent. Therefore, we identify such code from the monolithic RTOS binary and synthesize a slice for effective testing. Specifically, SFuzz first identifies functions that handle user input, constructs call graphs that start from callers of these functions, and leverages forward slicing to build the execution tree based on the call graphs and pruning the paths independent of external inputs. Then, it detects and handles roadblocks within the coarse-grain scope that hinder effective fuzzing, such as instructions unrelated to the user input. And then, it conducts coverage-guided fuzzing on these code snippets. Finally, SFuzz leverages forward and backward slicing to track and verify each path constraint and determine whether a bug discovered in the fuzzer is a real vulnerability. SFuzz successfully discovered 77 zero-day bugs on 35 RTOS samples, and 67 of them have been assigned CVE or CNVD IDs. Our empirical evaluation shows that SFuzz outperforms the state-of-the-art tools (e.g., UnicornAFL) on testing RTOS.
Although query-based systems (QBS) have become one of the main solutions to share data anonymously, building QBSes that robustly protect the privacy of individuals contributing to the dataset is a hard problem. Theoretical solutions relying on differential privacy guarantees are difficult to implement correctly with reasonable accuracy, while ad-hoc solutions might contain unknown vulnerabilities. Evaluating the privacy provided by QBSes must thus be done by evaluating the accuracy of a wide range of privacy attacks. However, existing attacks against QBSes require time and expertise to develop, need to be manually tailored to the specific systems attacked, and are limited in scope. In this paper, we develop QuerySnout, the first method to automatically discover vulnerabilities in query-based systems. QuerySnout takes as input a target record and the QBS as a black box, analyzes its behavior on one or more datasets, and outputs a multiset of queries together with a rule to combine answers to them in order to reveal the sensitive attribute of the target record. QuerySnout uses evolutionary search techniques based on a novel mutation operator to find a multiset of queries susceptible to lead to an attack, and a machine learning classifier to infer the sensitive attribute from answers to the queries selected. We showcase the versatility of QuerySnout by applying it to two attack scenarios (assuming access to either the private dataset or to a different dataset from the same distribution), three real-world datasets, and a variety of protection mechanisms. We show the attacks found by QuerySnout to consistently equate or outperform, sometimes by a large margin, the best attacks from the literature. We finally show how QuerySnout can be extended to QBSes that require a budget, and apply QuerySnout to a simple QBS based on the Laplace mechanism. Taken together, our results show how powerful and accurate attacks against QBSes can already be found by an automated system, allowing for highly complex QBSes to be automatically tested "at the pressing of a button". We believe this line of research to be crucial to improve the robustness of systems providing privacy-preserving access to personal data in theory and in practice.
Current research in the automotive domain has proven the limitations of the Controller Area Network (CAN) protocol from a security standpoint. Application-layer attacks, which involve the creation of malicious packets, are deemed feasible from remote but can be easily detected by modern Intrusion Detection Systems (IDSs). On the other hand, more recent link-layer attacks are stealthier and possibly more disruptive but require physical access to the bus. In this paper, we present CANflict, a software-only approach that allows reliable manipulation of the CAN bus at the data link layer from an unmodified microcontroller, overcoming the limitations of state-of-the-art works. We demonstrate that it is possible to deploy stealthy CAN link-layer attacks from a remotely compromised ECU, targeting another ECU on the same CAN network. To do this, we exploit the presence of pin conflicts between microcontroller peripherals to craft polyglot frames, which allows an attacker to control the CAN traffic at the bit level and bypass the protocol's rules. We experimentally demonstrate the effectiveness of our approach on high-, mid-, and low-end microcontrollers, and we provide the ground for future research by releasing an extensible tool that can be used to implement our approach on different platforms and to build CAN countermeasures at the data link layer.
In this paper, we systematically study the security of the current ROS2 implementation from three perspectives. By abstracting the key functions from the ROS2 native implementation, we first formally describe the ROS2 system communication workflow and model it using a concurrent modeling language. Second, we verify the model with some key security properties through a model checker, and successfully identify four security vulnerabilities in ROS2's native security module: Secure ROS2 (SROS2). To validate these flaws, we set up simulation and physical multi-robot testbeds running different real-world workloads developed by Open Robotics and Amazon AWS Robotics. We demonstrate that an adversary can exploit these vulnerabilities to totally invalidate the security protection offered by SROS2, and obtain unauthorized permissions or steal critical information. Third, to enhance the security of ROS2, we propose a general defense solution based on the private broadcast encryption scheme. We run different workloads and benchmarks to show the efficiency and security of our defense. Our findings have been acknowledge by ROS2 official, and the suggested mitigation has been implemented in the latest SROS2 version.
Speaker Recognition Systems (SRSs) grant access to legitimate users based on voiceprint. Recent research has shown that SRSs can be bypassed during the training phase (backdoor attacks) and the recognition phase (evasion attacks). In this paper, we explore a new attack surface of SRSs by presenting an enrollment-phase attack paradigm, named FenceSitter, where the adversary poisons the SRS using imperceptible adversarial ambient sound when the legitimate user registers into the SRS. The tainted voiceprint extracted by the SRS allows both the adversary and the legitimate user to access the system in all future recognition phases. To materialize such attack, we interleave carefully-designed continuous adversarial perturbations into innocent-sounding ambient sound. As computing adversarial perturbations over a long sequence of ambient sound carrier is intractable, we optimize over adversarial segments with content desensitization and physical realization. In addition, the attack is made available under the black-box settings by gradient estimation based on the natural evolution strategy. Extensive experiments have been conducted on both English and Chinese voice datasets for close-set identification (CSI), open-set identification (OSI), and speaker verification (SV) tasks. The results under various digital and physical conditions have verified the effectiveness and robustness of FenceSitter. With live enrollment experiments and user study, we further validate the practicality of FenceSitter. Our work reveals the vulnerability of SRSs during the enrollment phase, which may spur future research in improving the security of SRSs. 2ff7e9595c
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