Megalodon GitHub Supply Chain Attack Injected Malicious Actions into 5,561 Repos

Researchers disclosed a large-scale automated supply chain attack dubbed Megalodon that pushed 5,718 malicious commits into 5,561 GitHub repositories in less than six hours, using forged CI/CD bot identities and benign-looking commit messages to slip in malicious GitHub Actions workflow files. The workflows requested elevated permissions and carried base64-encoded bash payloads that executed after maintainers merged the changes, harvesting CI/CD environment data, cloud credentials, SSH keys, Docker and Kubernetes secrets, Vault and Terraform credentials, GitHub OIDC tokens, and other source-code and developer secrets. Investigators said the stolen data was exfiltrated over HTTP POST requests to 216.126.225[.]129:8443, with two workflow variants observed, including payloads labeled SysDiag and Optimize-Build.

The most visible downstream impact was a compromise of the Tiledesk repository, where a malicious workflow change led to the publication of poisoned @tiledesk/tiledesk-server npm versions 2.18.6 through 2.18.12. Reporting tied the activity to a broader pattern of software supply chain abuse associated with TeamPCP, whose earlier incidents affected major open-source and commercial projects and prompted npm to invalidate some write-capable granular access tokens that could bypass 2FA protections. Security firms urged organizations to review repositories for unauthorized workflow changes, block the identified command-and-control infrastructure, rotate exposed secrets and keys, and inspect cloud and CI logs for signs of credential theft or cloud impersonation.