We present a new general technique for protecting clients in distributed systems against Remote Man-at-the-end (R-MATE) attacks. Such attacks occur in settings where an adversary has physical access to an untrusted client device and can obtain an advantage from tampering with the hardware itself or the software it contains.

JavaScript is widely used to provide client-side functionality in Web applications. To provide services ranging from maps to advertisements, Web applications may incorporate untrusted JavaScript code from third parties. The trusted portion of each application may then expose an API to untrusted code, interposing a reference monitor that mediates access to security-critical resources. However, a JavaScript reference monitor can only be effective if it cannot be circumvented through programming tricks or programming language idiosyncrasies. In order to verify complete mediation of critical resources for applications of interest, we define the semantics of a restricted version of JavaScript devised by the ECMA Standards committee for isolation purposes, and develop and test an automated tool that can soundly establish that a given API cannot be circumvented or subverted. Our tool reveals a previously-undiscovered vulnerability in the widely-examined Yahoo! AD Safe filter and verifies confinement of the repaired filter and other examples from the Object-Capability literature.

Source code obfuscation is a protection mechanism widely used to limit the possibility of malicious reverse engineering or attack activities on a software system. Although several code obfuscation techniques and tools are available, little knowledge is available about the capability of obfuscation to reduce attackers' efficiency, and the contexts in which such an efficiencymay vary.

The remote trust problem aims to address the issue of verifying the execution of a program running on an un-trusted host which communicates regularly with a trusted server. One proposed solution to this problem relies on a centralized scheme using assertions and replication to withhold usable services from a tampered client. We show how to extend such a scheme to a distributed trusted hardware such as tamper-resistant smartcards. We compared the performance and security of the proposed distributed system to the original centralized scheme on a case study. Our results indicate that, compared to a centralized scheme, our distributed trust scheme has dramatically lower network traffic, and smaller memory and computational requirements on the trusted server.