Large-scale analysis of format string vulnerabilities in Debian Linux

Format-string bugs are a relatively common security vulnerability, and can lead to arbitrary code execution. In collaboration with others, we designed and implemented a system to eliminate format string vulnerabilities from an entire Linux distribution, using type-qualifier inference, a static analysis technique that can find taint violations. We successfully analyze 66% of C/C++ source packages in the Debian 3.1 Linux distribution. Our system finds 1,533 format string taint warnings. We estimate that 85% of these are true positives, i.e., real bugs; ignoring duplicates from libraries, about 75% are real bugs. We suggest that the technology exists to render format string vulnerabilities extinct in the near future.