GitHub, the world's biggest code repository and DevOps platform, fell victim to a malicious Visual Studio Code (VS Code) extension. The company's initial assessment is that only internal repositories were exfiltrated. The incident was reported by GitHub on X, with follow-up posts revealing a "poisoned VS Code extension" as the cause. The Microsoft-owned code shack continues to "analyze logs, validate secret rotation, and monitor for any follow-on activity." One GitHub post references "the attacker's current claims of ~3,800 repositories" as consistent with its investigation. This may refer to a post attributed to TeamPCP, the malware crew linked to the Shai-Hulud worm, the code for which has been published and caused widespread damage. In a post, the crew advertised GitHub's internal source code for sale, claiming around 4,000 repositories. They said it was not a ransom and if no buyer was found, they would leak the code for free. Claims like these should be treated with caution. A key concern for GitHub users is whether private repositories are at risk, either immediately or in the future if the attackers have gained a foothold into internal systems via stolen credentials. Risks include leakage of commercial code and credentials. Although best practice is not to check secrets into any repository, public or private, some organizations are less disciplined about this when repositories are private. Last month, Wiz Research discovered a remote code execution flaw in GitHub.com and GitHub Enterprise Server (the self-hosted version), which the researchers said was "remarkably easy to exploit." The vulnerability was discovered using AI. Developer reactions to GitHub's latest problems combine alarm and resignation – plus some humor. "How did the attackers find a large enough uptime window to get in?" quipped one. GitHub is in some difficulty. This compromise comes after a surge in npm attacks, many related to Shai-Hulud code, which the company has failed to prevent despite being aware of the issue since September 2025. Further, the platform has reliability issues caused in part by AI bots hoovering public code to feed large language models – problems that led HashiCorp co-founder Mitchell Hashimoto to declare GitHub "no longer a place for serious work." Another said that "the era where a developer machine with source code access also has access to meaningful security systems should be over. Internal repository access should mean nothing... GitHub compromise could happen at any time, even from GitHub themselves." Issues with cloud platforms also increase the appeal of self-hosted systems such as the open source
Checkmarx’s software engineers are still working to remove a malicious version of the code security outfit's Jenkins plugin after detecting an unauthorized upload over the weekend. It updated customers on Saturday, May 9, after discovering a version of its AST Scanner, which is used for security scans in Jenkins CI pipelines, was made available via the Jenkins Marketplace. “We are aware that a modified version of the Checkmarx Jenkins AST plugin was published to the Jenkins Marketplace,” it said in a statement. “We are in the process of publishing a new version of this plug-in.” Versions published as of May 9, 2026, should not be trusted, it added, before urging all users to check they’re running the correct release (2.0.13-829.vc72453fa_1c16) published on December 17, 2025. Installed by several hundred controllers, the plugin remains available at the time of writing, and appears as the most recently available version, although pull requests actioned on Monday morning suggest this will soon be pulled down. “What makes this particularly dangerous for Jenkins users is the trust model at play,” said SOCRadar in its coverage. “The Checkmarx Jenkins plugin is a tool people install specifically to improve the security of their pipelines. “A backdoored version doesn’t just compromise one project; it rides trusted infrastructure into every build pipeline it touches, with access to source code, environment variables, tokens, and whatever secrets the runner can see.” Security engineer Adnan Khan spotted the compromise quickly over the weekend. The crew behind the early supply chain attack affecting Checkmarx in April, TeamPCP, defaced the company’s GitHub and published six packages, each with a description alluding to the Shai-Hulud wormable malware. These packages no longer appear on Checkmarx’s GitHub, but TeamPCP made multiple changes to the AST plugins page, renaming it to “Checkmarx-Fully-Hacked-by-TeamPCP-and-Their-Customers-Should-Cancel-Now,” and altering the description to claim CheckMarx failed to rotate its secrets. The latest infiltration of Checkmarx’s internals marks the third time TeamPCP has compromised the company’s packages in as many months. As previously seen in The Register, the crooks successfully targeted Checkmarx’s AST plugin for GitHub Actions and its KICS static analysis tool back in March, deploying credential-stealing malware. SOCRadar said the latest TeamPCP compromise of the Jenkins plugin suggests that either TeamPCP was telling the truth about Checkmarx’s secrets rotation, or its members took advantage of an additional persistence mechanism that the security vendor failed to notice during its response to the March intrusion. ®
The Challenge As stated in PART 1 of this blog, the Windows endpoint defense technology stack in a mature organization represents a challenge for Red Teamer initial access operations. For […]
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