Concurrency bugs occur when a resource is accessed by several entities without proper synchronization. These bugs can lead to highly critical vulnerabilities, including kernel and software CVEs. That is why numerous studies have already explored how to detect and prevent the introduction of concurrency bugs in programs and source code. However, little attention has been given to mitigation techniques aimed at preventing the exploitation of remaining concurrency vulnerabilities. Instead, security relies only on hindering exploitation steps that follows the vulnerability triggering. This article explores how operating system schedulers can be hardened to mitigate the exploitation of concurrency vulnerabilities. Such exploitation consists of triggering specific scheduling orders between entities that invalidate the property of the accessed resource. Drawing inspiration from successful mitigation techniques such as ASLR, we propose a modification of the Linux EEVDF scheduler that reduces scheduling predictability, preventing attackers from determining when the target is executing and from reliably triggering the exploit within the vulnerability window. To ensure that the proposed techniques are practical, the evaluation is conducted against the exploitation of real-world CVEs. We show that implementation of our techniques are effective against these exploits. We also show the existence of a trade-off between the execution time overhead introduced by the scheduler modification and the resulting security guarantees. These promising results advocate the conception of new scheduling algorithms that integrate unpredictability by design.
Companies and other organizations are increasingly exposed to cyber threats. To effectively prepare their defense, organizations need to understand possible attacks and their implications, as well as the effects of possible countermeasures. These insights are necessary for making sound decisions on where to focus the organization’s efforts: e.g., which nodes are especially critical and need hardening, how to optimize the network topology, how to best implement intrusion protection etc. This paper presents simTIM, a simulator that helps organizations obtain clarity about these aspects. The simulator is model-based, built on the TIM meta-model introduced in recent work. simTIM allows the modeling of the organization’s IT assets, potential attacks and their effects, and mitigations. simTIM supports probabilistic reasoning, temporal aspects, partial observability, and financial incentives. With simTIM, organizations can easily perform what-if analysis to assess the implications of different cyber defense strategies. The paper describes the design and implementation, and illustrates the practical use of simTIM.
Confidential computing is experiencing rapid adoption as organizations increasingly seek to protect sensitive data during processing in cloud and edge environments. As this paradigm matures, there is a growing need for transparent, portable, and auditable solutions. However, existing solutions are often tied to proprietary solutions and architectures, limiting transparency, portability, and security. In this paper, we present a novel secure abstraction layer that combines WebAssembly (Wasm) with the open source RISC-V Trusted Execution Environment (TEE) framework Keystone. Our approach embeds a Wasm runtime inside a Keystone enclave and introduces a multiplexed edge call mechanism to transparently bridge the WebAssembly System Interface (WASI) with the untrusted host operating system, while respecting Keystone’s architectural constraints. This design enables unmodified Wasm applications to execute securely inside enclaves without requiring developers to write TEE-specific code. We detail the runtime adaptations required to support the latest version of WASI, discuss design trade-offs, and analyze security implications of host-mediated system calls. We evaluate our prototype using a representative Rust-based web application on both QEMU and a VisionFive 2 RISC-V board. Experimental results show an average overhead of approximately 10
Ensuring compliance with cybersecurity standards is essential for auditable, consistent, and legally aligned security processes. Manual checks by security experts may be prone to subjectivity, cost, and potential bias during assessments. On the contrary, full automation may lack accountability and present corner cases where a human analysis is crucial to correctly assess the situation. This paper introduces an audit support system that unifies technical and process compliance with automated recommendations. Grounded in international standards and research, the system formalizes compliance requirements and models the execution of security governance processes (specifically, Incident Management) against relevant standards. It enables automatic auditing through conformity assessment and contextualized recommendations using process trace alignment and generative AI, with human oversight. Evaluation through two case studies, expert reviews, and quantitative analysis shows the system delivers accurate, context-aware compliance insights.
Certificate Authorities (CAs) are a cornerstone of web security, as browsers and applications fully trust authentication assertions issued by them. Root stores in user devices contain the CAs that serve as trust anchors for certificate validation. However, these root CAs often extend their authority to organizations outside their administrative boundaries, known as intermediate CAs. Although root stores have been extensively studied in previous work, intermediate CAs have received little attention, despite their equivalent authentication capabilities and crucial role in determining the actual perimeter of trust. This work provides the first systematic overview of the intermediate CA ecosystem in the Web Public Key Infrastructure (Web PKI). Starting from the Mozilla root store, we investigate over 1800 CA certificates and find that trust extends well beyond the root store: 150 additional CAs from 18 countries not represented among root CAs are implicitly trusted by any relying party. We show that root CAs delegate trust to intermediate CAs in countries with substantial political distance from their own, substantially expanding the geopolitical diversity of trusted certificate issuers. Finally, by cross-referencing our dataset against Certificate Transparency Logs, we identify CAs that violate Mozilla’s mandatory disclosure policies, further undermining the ecosystem’s transparency.
