This Burp extension helps fingerprinting the version of remote software based on static artifacts by comparing them to a Git repository.
More information can be found in the presentation and in the talk recording.
Select a number of Request-Response pairs corresponding to static artifacts belonging to the target software component from (e.g.: CSS, JS, documentations). This can typically be done on the Proxy or Target tabs. Bring up the right-click menu and select Extensions/Git version/Find version from Git.
A directory chooser window pops up, where you should select the locally stored .git directory of the target software.
The extensions matches file contents with the revisions stored in the Git repo, and reports a commit/time range that matches the static artifacts on the server.
The JAR can also be used as a standalone utility:
java -cp burp-git-version.jar:burp-extender-api-2.3.jar burp.BurpExtender /path/to/.git <githash0> <githash1> ...
You can grab the Burp Extender API definition from Maven or similar repository.
It's important to note that the command-line interface expects Git object hashes instead of file paths. The Git hashes are not plain-old SHA-1's, you can generate them like this:
git hash-object <filename>