The software supply chain is an increasingly common attack vector for malicious actors. The Node.js ecosystem has been subject to a wide array of attacks, likely due to its size and prevalence. To counter such attacks, the research community and practitioners have proposed a range of static and dynamic mechanisms, including process- and language-level sandboxing, permission systems, and taint tracking. Drawing on valuable insight from these works, this paper studies a runtime protection mechanism for (the supply chain of) Node.js applications with the ambitious goals of compatibility, automation, minimal overhead, and policy conciseness.

Cryptographic communication protocols provide confidentiality, integrity and authentication properties for end-to-end communication under strong corruption attacks, including, notably, post-compromise security (PCS). Most protocols are designed for one-to-one communication. Protocols for group communication are less common, less efficient, and tend to provide weaker security guarantees. This is because group communication poses unique challenges, such as coordinated key updates, changes to group membership and complex post-compromise recovery procedures. We need to tackle this complex challenge as a community. Thus, the Internet Engineering Task Force (IETF) has created a working group with the goal of developing a sound standard for a continuous asynchronous key-exchange protocol for dynamic groups that is secure and remains efficient for large group sizes. The current version of the Messaging Layer Security (MLS) security protocol is in a feature freeze, i.e., no changes are made in order to provide a stable basis for cryptographic analysis. The key schedule and TreeKEM design are of particular concern since they are crucial to distribute and combine several keys to achieve PCS. In this work, we study the MLS continuous group key derivation (CGKD) which comprises the MLS key schedule, TreeKEM and their composition, as specified in Draft 11 of the MLS RFC, while abstracting away signatures, message flow and authentication guarantees. We establish the uniqueness and key indistinguishability properties of the MLS CGKD as computational security properties.