Thread by @joaxcar

Yesterday I made it into top 5 on @GitLab bug bounty program 🥳, at the same time crossing 100k in bounties from the same.

Some people are asking me how to get started or where and what to look for. I thought I could share a practical guide if anyone care for a thread [1/6]

The easiest way to find out what to look for is the latest security release. See what others are finding at the moment, usually there are more bugs of the same type present [2/6]

about.gitlab.com/releases/2022/…

In 15.3.2 there were five DOS bugs, all given a medium severity. DOS bugs like these are present in almost every GitLab security release lately. They are easy enough to replicate, and one can hunt for them both statically and dynamically. [3/6]

Now go to the GitLab issue tracker and search for old DOS security issues. Read them all gitlab.com/gitlab-org/git…

Then install any vulnerable version in a docker container docs.gitlab.com/ee/install/doc…
and replicate some of the issues. Try to recreate the ones from 15.3.2 [4/6]

Now think about how these issues were fixed and what caused them. Look in the merge requests for 15.3.2 gitlab.com/gitlab-org/git…

And read how they were mitigated. Try to see if you can find a flaw in the fix, or if anything can point to other vulnerable areas. [5/6]

If you follow these steps you will have learned a LOT about security, DOS issue, GitLab, setting up environments and replicating vulnerabilities. You will also most certainly be in a great position to finding your first bug on the GitLab @Hacker0x01 program. [6/6]

Some follow up here [7/6]

1. ⚠️ Do not ever test DOS on gitlab[.]com or other production instances! Only self-hosted

2. Why DOS? It's arbitrary, the point is to find an area to focus on to not get analysis paralysis

3. This is how I started, but with a focus on GraphQL AC