Once executed, the malicious workflow harvested secrets from GitHub Actions environments and transmitted them to an attacker-controlled server through a curl POST request. In FastUUID’s case, the attackers accessed the project’s PyPI token, although no malicious package versions were published before the compromise was detected and contained. Further investigation revealed that the attack extended well beyond a single project. Researchers found similar workflow injections across at least 817 repositories, all exfiltrating data to the same domain. To maximize impact, the attackers enumerated secret variables from existing legitimate workflows and embedded them into their own files, ensuring multiple types of secrets could be stolen.
GitGuardian publicly disclosed the findings on September 5, raising issues in 573 affected repositories and notifying security teams at GitHub, npm, and PyPI. By that time, about 100 repositories had already identified the unauthorized commits and reverted them. Soon after the disclosures, the exfiltration endpoint used by the attackers went offline, halting further data transfers.
The scope of the incident is significant, with researchers estimating that roughly 3,325 secrets were exposed. These included API tokens, access keys, and database credentials spanning several major platforms. At least nine npm packages and 15 PyPI projects remain directly affected, with the risk that compromised tokens could allow the release of malicious or trojanized versions if not revoked. GitGuardian noted that some companies had their entire SDK portfolios compromised, with repositories in Python, Rust, JavaScript, and Go impacted simultaneously.
While the attack bears some resemblance to the s1ngularity campaign reported in late August, GitGuardian stated that it does not see a direct connection between the two. Instead, GhostAction appears to represent a distinct, large-scale attempt to exploit open-source ecosystems through stolen maintainer credentials and poisoned automation workflows. The findings underscore the growing challenges in securing supply chains that depend heavily on public code repositories and automated build systems.
