The architecture of software systems evolves along with their upgrades and maintenance, inevitably creating a gap between the defact architecture and the designed one. To perceive and fix the discrepancy, clustering-based architecture recovery methods have been developed to re-engineer the real-time system architecture from the code implementation. However, existing solutions still face several limitations. They underutilize both code-level and architecture-level semantics underlying the source code. Moreover, they overlook implicit structural dependencies that complement explicit ones to reflect code interactions. To address these challenges, we propose SemArc, an architecture recovery method that utilizes large language models to comprehend both implementation-level and architecture-level semantics, supported by well-established canonical architectural patterns as a knowledge base. SemArc also incorporates both implicit and explicit dependencies to complete the system behavior representations. Additionally, SemArc introduces a component-as-anchor guided clustering algorithm to improve the clustering process. We evaluated SemArc on 15 software systems written in C/C++, Java, and Python, using five different metrics. The results demonstrate that SemArc outperforms seven baseline methods by an average of 32 percentage points. We also examined how three factors—code semantics, architectural semantics, and implicit dependencies—as well as different levels of architectural semantic descriptions, influence recovery accuracy. A case study on the Bash project indicates that SemArc has the potential to yield even more precise recovery results than those labeled by humans.

The rapid development of Android apps primarily benefits from third-party libraries that provide well-encapsulated functionalities. On the other hand, more and more malicious libraries are discovered in the wild, which brings new security challenges. Despite some previous studies focusing on the malicious libraries, however, most of them only study specific types of libraries or individual cases. The security community still lacks a comprehensive understanding of potentially malicious libraries (PMLs) in the wild.

Nowadays, protocols often use time to provide better security. For instance, critical credentials are often associated with expiry dates in system designs. However, using time correctly in protocol design is challenging, due to the lack of time related formal specification and verification techniques. Thus, we propose a comprehensive analysis framework to formally specify as well as automatically verify timed security protocols. A parameterized method is introduced in our framework to handle timing parameters whose values cannot be decided in the protocol design stage. In this work, we first propose timed applied p-calculus as a formal language for specifying timed security protocols. It supports modeling of continuous time as well as application of cryptographic functions. Then, we define its formal semantics based on timed logic rules, which facilitates efficient verification against various authentication and secrecy properties. Given a parameterized security protocol, our method either produces a constraint on the timing parameters which guarantees the security property satisfied by the protocol, or reports an attack that works for any parameter value. The correctness of our verification algorithm has been formally proved. We evaluate our framework with multiple timed and untimed security protocols and successfully find a previously unknown timing attack in Kerberos V.

Automatic loop-invariant generation is important in program analysis and verification. In this paper, we propose to generate loop-invariants automatically through learning and verification. Given a Hoare triple of a program containing a loop, we start with randomly testing the program, collect program states at run-time and categorize them based on whether they satisfy the invariant to be discovered. Next, classification techniques are employed to generate a candidate loop-invariant automatically. Afterwards, we refine the candidate through selective sampling so as to overcome the lack of sufficient test cases. Only after a candidate invariant cannot be improved further through selective sampling, we verify whether it can be used to prove the Hoare triple. If it cannot, the generated counterexamples are added as new tests and we repeat the above process. Furthermore, we show that by introducing a path-sensitive learning, i.e., partitioning the program states according to program locations they visit and classifying each partition separately, we are able to learn disjunctive loop-invariants. In order to evaluate our idea, a prototype tool has been developed and the experiment results show that our approach complements existing approaches.

Security of authentication protocols heavily relies on the confidentiality of credentials (or authenticators) like passwords and session IDs. However, unlike browser-based web applications for which highly evolved browsers manage the authenticators, Android apps have to construct their own management. We find that most apps simply locate their authenticators into the persistent storage and entrust underlying Android OS for mediation. Consequently, these authenticators can be leaked through compromised backup channels. In this work, we conduct the first systematic investigation on this previously overlooked attack vector. We find that nearly all backup apps on Google Play inadvertently expose backup data to any app with internet and SD card permissions. With this exposure, the malicious apps can steal other apps' authenticators and obtain complete control over the authenticated sessions. We show that this can be stealthily and efficiently done by building a proof-of-concept app named AuthSniffer. We find that 80 (68.4%) out of the 117 tested top-ranked apps which have implemented authentication schemes are subject to this threat. Our study should raise the awareness of app developers and protocol analysts about this attack vector.

In this paper, we describe our analysis of a recently proposed electric vehicle charing protocol. The protocol builds on complicated cryptographic primitives such as commitment, zero-knowledge proofs, BBS+ signature and etc. Moreover, interesting properties such as secrecy, authentication, anonymity, and location privacy are claimed on this protocol. It thus presents a challenge for formal verification, as existing tools for security protocol analysis lack support for all the required features. In our analysis, we employ and combine the strength of two state-of-the-art symbolic verifiers, Tamarin and Prove if, to check all important properties of the protocol.