Fuzzy whitelisting anti-malware systems and methods

Abstract

In some embodiments, an anti-malware system accounts for benign differences between non-malicious data objects, such as differences introduced by compilers and other polymorphisms. A target object is separated into a multitude of code blocks, and a hash is calculated for each code block. The obtained set of target hashes is then compared against a database of hashes corresponding to code blocks extracted from whitelisted objects. A target object may be labeled as whitelisted (trusted, non-malicious) if it has a substantial number of hashes in common with a whitelisted object. Objects which are slightly different from known whitelisted objects may still receive whitelisting status. By allowing a certain degree of mismatch between the sets of hashes of distinct objects, some embodiments of the present invention increase the efficiency of whitelisting without an unacceptable decrease in safety.