Event-aware information flow security in cyber–physical systems (CPSs) emphasizes the correlation among events. Event-aware noninterference is a security property capable to describe such a correlation. In light of the event-aware noninterference assessment problem, system modeling is a common means, and many studies have been done on such a problem by using formal modeling tools, i.e., Petri nets (PNs), at present. However, classical PNs suffer from the lack of modeling for patterns with semantic sharing of events, which can be modeled by labeled PNs (LPNs). In this article, we present the concept of semantics-based noninterference for the CPSs modeled by LPNs and focus on the assessment problem of semantics-based noninterference properties represented by semantics-based strong nondeterministic noninterference (SNNI) and extended bisimulation SNNI (EBSNNI). To this end, we first give the formal definitions of semantics-based SNNI and EBSNNI. Then, we analyze the assessment mechanisms of them according to the characteristics of semantic sharing of events in LPNs. On this basis, we provide the semantics-based noninterference assessment method involving the coarse and fine assessments to reveal the event-aware security of CPSs. Finally, a case study is provided to explain the significance of our research and the effectiveness of our method.

Although the number of exploitable vulnerabilities in software continues to increase, the speed of bug fixes and software updates have not increased accordingly.It is therefore crucial to analyze the source code and identify vulnerabilities in the early phase of software development.However, vulnerability location in most of the current machine learning-based methods tends to concentrate at the function level.It undoubtedly imposes a burden on further manual code audits when faced with largescale source code projects.In this paper, a fine-grained source code vulnerability detection model based on Graph Neural Networks (GNNs) is proposed with the aim of locating vulnerabilities at the function level and line level.Our empirical evaluation on different C/C++ datasets demonstrated that our proposed model outperforms the state-of-the-art methods and achieves significant improvements even when faced with more complex, real-project source code.

One of the noteworthy investigations in workflows is the implementation of authorization-related security requirements. There are two typical security requirements, i.e., separation of duty (SoD) and binding of duty (BoD). However, most of the previous works are only focused on SoD while ignoring BoD. In this article, we consider both of them by proposing an extended-structural implementation approach, namely beacon-based firing control, to enforce security requirements. Thanks to the flexibility of beacon-based firing control, both BoD and SoD can be enforced in a straightforward way with no sophisticated operations for their implementation, although they are a pair of security requirements in conflict. As a preparation of beacon-based firing control, we define the beacon-extended Petri nets (PNs) by introducing a new object, namely beacon, to PNs so as to lay the foundation. In addition, we present the firing-based linear equations and inequalities for BoD and SoD to provide the standardized descriptions for their implementation. For the sake of expansibility, the applicability analysis is provided for the more general security requirements. Ultimately, the comparative experiments and discussions are presented to show the effiectiveness and efficiency of the proposed approach.

Authorization-related security requirements are of great significance in workflow management systems. Existing studies are restricted in their scopes of research. There is no unified principle for their implementation. In this paper, we focus on the unification of authorization-related security requirements using Petri nets (PNs). These security requirements are expressed by constraints, being imposed on tasks, namely task-based security requirements (TSRs). By downgrading TSRs to a kind of authorization-conflict relationship, we provide a standardized expression for TSRs. Such a standardized expression can be transformed to firing-based linear inequalities which are a more general representation of constraints. Then, we propose the firing control for the unified implementation of TSRs based on firing-based linear inequalities. In fact, firing control is enforced by structural controllers namely monitors which are structurally consistent with PNs. For the sake of conciseness, simplification techniques are provided for the monitors. Ultimately, the experiments and discussions are presented to show the performance and advantages of the proposed approach.