Discoverer: Automatic Protocol Reverse Engineering from Network Traces
Application-level protocol specifications are useful for many security applications, including intrusion prevention and detection that performs deep packet inspection and traffic normalization, and penetration testing that generates network inputs to an application to uncover potential vulnerabilities. However, current practice in deriving protocol specifications is mostly manual.
In this paper, we present Discoverer, a tool for automatically reverse engineering the protocol message formats of an application from its network trace. A key property of Discoverer is that it operates in a protocol-independent fashion by inferring protocol idioms commonly seen in message formats of many application-level protocols.
We evaluated the efficacy of Discoverer over one text protocol (HTTP) and two binary protocols (RPC and CIFS/SMB) by comparing our inferred formats with true formats obtained from Ethereal [5]. For all three protocols, more than 90% of our inferred formats correspond to exactly one true format; one true format is reflected in five inferred formats on average; our inferred formats cover over 95% of messages, which belong to 30-40% of true formats observed in the trace.
SpyProxy: Execution-based Detection of Malicious Web Content
This paper explores the use of execution-based Web content analysis to protect users from Internet-borne malware. Many anti-malware tools use signatures to identify malware infections on a user’s PC. In contrast, our approach is to render and observe active Web content in a disposable virtual machine before it reaches the user’s browser, identifying and blocking pages whose behavior is suspicious. Execution-based analysis can defend against undiscovered threats and zero-day attacks. However, our approach faces challenges, such as achieving good interactive performance, and limitations, such as defending against malicious Web content that contains non-determinism. To evaluate the potential for our execution-based technique, we designed, implemented, and measured a new proxy-based anti-malware tool called SpyProxy.
SpyProxy intercepts and evaluates Web content in transit from Web servers to the browser. We present the architecture and design of our SpyProxy prototype, focusing in particular on the optimizations we developed to make on-the-fly execution-based analysis practical.
We demonstrate that with careful attention to... [ Read More (0.4k in body) ]
