Original Post: Taint mode is now in beta
Semgrep’s Taint mode has moved to General Availability (GA), facilitating easier writing of rules to detect injection vulnerabilities through taint analysis—a data-flow analysis technique. Initially, Semgrep aimed to enforce secure code defaults using syntax-aware matching, but both the community and r2c found it effective for identifying vulnerabilities. While traditional search mode could be used for this purpose, it often required cumbersome and less efficient “fake-taint” rules.
With the introduction of taint mode, which was initially experimental, users can now write more effective and maintainable taint-tracking rules. This mode accurately tracks the flow of untrusted data (sources) through the code to vulnerable functions (sinks) and recognizes sanitization processes. The recent improvements (in 2021 Q3) have refined this feature, making it more robust and ready for broader use.
Taint mode simplifies finding complex bugs and minimizes false positives by allowing customized definition of sources, sinks, and sanitizers. While traditional methods may lead to intricate and hard-to-maintain rules, taint mode offers a streamlined and powerful alternative. The Semgrep team continues to refine and expand the capabilities of taint mode for various programming languages, with a particular focus on JavaScript.
For further understanding, r2c provides resources including an introductory video and additional documentation. The Semgrep community is encouraged to try out taint mode and provide feedback to help improve the tool.
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