Machine Learning Methods for Software Vulnerability Detection

Software vulnerabilities are a primary concern in the IT security industry, as malicious hackers who discover these vulnerabilities can often exploit them for nefarious purposes. However, complex programs, particularly those written in a relatively low-level language like C, are difficult to fully scan for bugs, even when both manual and automated techniques are used. Since analyzing code and making sure it is securely written is proven to be a non-trivial task, both static analysis and dynamic analysis techniques have been heavily investigated, and this work focuses on the former. The contribution of this paper is a demonstration of how it is possible to catch a large percentage of bugs by extracting text features from functions in C source code and analyzing them with a machine learning classifier. Relatively simple features (character count, character diversity, entropy, maximum nesting depth, arrow count, "if" count, "if" complexity, "while" count, and "for" count) were extracted from these functions, and so were complex features (character n-grams, word n-grams, and suffix trees). The simple features performed unexpectedly better compared to the complex features (74% accuracy compared to 69% accuracy).