Microsoft’s open source tools were hacked to steal AI developers’ passwords

Microsoft has cut off access to dozens of its open source projects hosted on GitHub, as it investigates how hackers apparently compromised the projects and injected password-stealing malware into their code.

Many of the affected projects relate to Microsoft’s Azure cloud service and other tools that developers use to program with AI development applications, such as Claude Code, the Gemini command line interface, and VS Code.

According to security firm Cloudsmith and community malware analysis site OpenSourceMalware, who were among the first to report the hack, the malware allowed hackers to steal user passwords and other sensitive credentials when they opened the compromised tools in their AI encryption applications.

It is not immediately known how many people have downloaded the affected tools.

Microsoft has confirmed that it has withdrawn the repurchase agreements, as first reported by 404 Media. A Microsoft spokesperson acknowledged receipt of our email, but did not immediately comment.

At least 70 Microsoft projects have been “broken”, according to a message uploaded when trying to access project pages on GitHub, a code hosting site owned by Microsoft. “Access to this repository has been disabled by GitHub employees due to a violation of GitHub’s Terms of Service.”

This is the latest example in recent months of hackers breaching widely popular open source projects with the aim of planting malware on a large number of users who had installed the code on their computers. These hacks are known as “supply chain” attacks because they target code that is often used in a large number of software products, or by a specific type of user, which can be useful for a hack as they sometimes have access to cloud systems and large amounts of customer data.

While it is not uncommon for lone developers of open source projects to be targeted by hackers — in some cases as part of long-term efforts to gain developer trust — it is rare for large tech giants like Microsoft, which have the resources to defend against these types of attacks, to be hacked.

This is the second known Microsoft hack in the past few weeks that allowed hackers to break into its open source projects, according to Ars Technica. In mid-May, security researchers said that Microsoft’s open source project Durable Task, a tool that helps developers build applications, had been hacked. OpenSourceMalware said Microsoft’s latest incident is a “recompromise” of the Permanent Mission project, suggesting that Microsoft may not have been able to take down the hackers on its first attempt or in a completely new and distinct hack.