Race Against The Workflows: Stealing GitHub Tokens from Docker Images
Gaetan Ferry and Guillaume Valadon
CI/CD pipelines have become prime targets for supply chain attacks, enabling persistent compromise of distribution builds and secrets. In the GitHub Actions ecosystem specifically, documented attack techniques typically focus on developer mistakes, such as environment injections and pwn requests. However, research scanning Docker Hub has revealed a different class of vulnerability: over 240,000 GitHub authentication tokens leaked through a seemingly benign workflow pattern using legitimate, official actions, in particular the combination of actions/checkout and the common COPY . Docker antipattern.
This presentation will explain the complete vulnerability chain from workflow execution to token exposure, demonstrate exploitation techniques that overcome default security mechanisms — racing against token expiration while exploiting elevated workflow permissions — and provide a multi-layered defense strategy including critical action version updates and Docker hardening best practices.
Licensed to the public under https://creativecommons.org/licenses/by-sa/4.0/