Attack Chain

1. An attacker forks the target CoreShop repository.
2. The attacker modifies a file within the forked repository that satisfies the paths condition defined in the static.yml workflow, such as src/dummy.php or composer.json.
3. The attacker crafts a malicious payload and injects it into the bin/console file within their forked repository. This payload is designed to execute arbitrary commands on the GitHub Actions runner.
4. The attacker commits the changes, including the modified bin/console file, to their forked repository.
5. The attacker opens a pull request (PR) targeting the 5.0 or next branch of the original CoreShop repository.
6. The Static Tests workflow is automatically triggered upon receiving the pull request.
7. The workflow executes the bin/console script from the attacker’s branch, resulting in the execution of the malicious payload within the GitHub Actions runner environment.
8. The attacker obtains RCE within the runner’s context, gaining access to secrets and potentially modifying repository contents.

Impact

Successful exploitation allows an attacker to execute arbitrary code within the GitHub Actions runner environment. Because pull_request_target runs in the context of the base repository, the runner has access to repository secrets (e.g., PIMCORE_SECRET, PIMCORE_PRODUCT_KEY) loaded in the environment. An attacker can exfiltrate these secrets, modify repository contents (if the token has write permissions), or abuse the runner’s computing resources. This can lead to sensitive data exposure, code tampering, and resource hijacking.

Recommendation

• Modify the GitHub Actions workflow (.github/workflows/static.yml) to avoid checking out untrusted PR code (head.ref) when using pull_request_target.
• Implement a separated architecture using the workflow_run event, as suggested in the overview.
• Monitor GitHub Actions logs for suspicious execution of bin/console with unexpected commands, using the detection rules provided below.
• Apply the recommended mitigation from the advisory (https://github.com/advisories/GHSA-q58j-g3f4-h26h).