The cascading provide chain assault that initially targeted Coinbase earlier than changing into extra widespread to single out customers of the “tj-actions/changed-files” GitHub Motion has been traced additional again to the theft of a private entry token (PAT) associated to SpotBugs.
“The attackers obtained preliminary entry by making the most of the GitHub Actions workflow of SpotBugs, a well-liked open-source device for static evaluation of bugs in code,” Palo Alto Networks Unit 42 said in an replace this week. “This enabled the attackers to maneuver laterally between SpotBugs repositories, till acquiring entry to reviewdog.”
There’s proof to recommend that the malicious exercise started way back to November, 2024, though the assault in opposition to Coinbase didn’t happen till March 2025.
Unit 42 mentioned its investigation started with the data that reviewdog’s GitHub Motion was compromised attributable to a leaked PAT related to the challenge’s maintainer, which subsequently enabled the menace actors to push a rogue model of “reviewdog/action-setup” that, in flip, was picked up by “tj-actions/changed-files” attributable to it being listed as a dependency by way of the “tj-actions/eslint-changed-files” motion.
It has since been uncovered that the maintainer was additionally an lively participant in one other open-source challenge referred to as SpotBugs.
The attackers are mentioned to have pushed a malicious GitHub Actions workflow file to the “spotbugs/spotbugs” repository underneath the disposable username “jurkaofavak,” inflicting the maintainer’s PAT to be leaked when the workflow was executed.
It is believed that the identical PAT facilitated entry to each “spotbugs/spotbugs” and “reviewdog/action-setup,” that means the leaked PAT might be abused to poison “reviewdog/action-setup.”
“The attacker in some way had an account with write permission in spotbugs/spotbugs, which they have been in a position to make use of to push a department to the repository and entry the CI secrets and techniques,” Unit 42 mentioned.
As for the way the write permissions have been obtained, it has come to mild that the consumer behind the malicious decide to SpotBugs, “jurkaofavak,” was invited to the repository as a member by one of many challenge maintainers themselves on March 11, 2025.
In different phrases, the attackers managed to acquire the PAT of the SpotBugs repository to ask “jurkaofavak” to grow to be a member. This, the cybersecurity firm mentioned, was carried out by making a fork of the “spotbugs/sonar-findbugs” repository and making a pull request underneath the username “randolzfow.”
“On 2024-11-28T09:45:13 UTC, [the SpotBugs maintainer] modified one of many ‘spotbugs/sonar-findbugs workflows to make use of their very own PAT, as they have been having technical difficulties in part of their CI/CD course of,” Unit 42 defined.
“On 2024-12-06 02:39:00 UTC, the attacker submitted a malicious pull request to spotbugs/sonar-findbugs, which exploited a GitHub Actions workflow that used the pull_request_target set off.”
The “pull_request_target” set off is a GitHub Actions workflow set off that enables workflows working from forks to entry secrets and techniques – on this case, the PAT – resulting in what’s referred to as a poisoned pipeline execution assault (PPE).
The SpotBugs maintainer has since confirmed that the PAT that was used as a secret within the workflow was the identical entry token that was later used to ask “jurkaofavak” to the “spotbugs/spotbugs” repository. The maintainer has additionally rotated all of their tokens and PATs to revoke and stop additional entry by the attackers.
One main unknown in all that is the three-month hole between when the attackers leaked the SpotBugs maintainer’s PAT and after they abused it. It is suspected that the attackers have been holding an eye fixed out on the tasks that have been depending on “tj-actions/changed-files” and waited to strike a high-value goal like Coinbase.
“Having invested months of effort and after attaining a lot, why did the attackers print the secrets and techniques to logs, and in doing so, additionally reveal their assault?,” Unit 42 researchers contemplated.
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