File Guard: automatic format-based media file sanitization

Abstract

This paper proposes a format-based file sanitization mechanism, File Guard, aiming at preventing software vulnerabilities from being triggered by input files. Based on our experiments and the statistics on Common Vulnerabilities and Exposures, we observed that most of the software vulnerabilities are exploited by malformed input files which violate their corresponding format standards. Hence, repairing the input file according to the format standard is effective in preventing the vulnerabilities from being exploited. In this work, we focus on media file types, such as image, audio, video. File Guard automatically sanitizes input files of known formats, disabling the files from triggering potential vulnerabilities in a target system (or a group of systems) with minimum data loss. Existing intrusion prevention systems and anti-virus tools typically compare the input file or executable with the ones which are known to be malicious, and eliminate such data or software before they get into the protected system. Instead of blocking the malicious or damaged input file, our mechanism repairs the data and provides a more user-friendly protection. File Guard can ensure that the input file meets its standard format and thus is not exploitable even by zero-day vulnerabilities.