Pierluigi Paganini January 31, 2023

GitHub confirmed that threat actors exfiltrated encrypted code signing certificates for some versions of GitHub Desktop for Mac and Atom apps.

GitHub this week disclosed a security breach, threat actors exfiltrated encrypted code signing certificates for some versions of GitHub Desktop for Mac and Atom apps.

In response to the incident, the Microsoft-owned company is started revoking the exposed certificates.

The following versions of GitHub Desktop for Mac will stop working on February 2, 2023: 3.0.2, 3.0.3, 3.0.4, 3.0.5, 3.0.6, 3.0.7, 3.0.8, 3.1.0, 3.1.1, and 3.1.2. Similarly, Atom versions 1.63.0 and 1.63.1 will stop working on February 2, in this case users are urged to download a previous Atom version, because Atom was discontinued in December 2022.

The company pointed out that customer data was not impacted because they were not stored in the impacted repositories.

“On December 6, 2022, repositories from our atom, desktop, and other deprecated GitHub-owned organizations were cloned by a compromised Personal Access Token (PAT) associated with a machine account.” reads the notice published by GitHub. “Once detected on December 7, 2022, our team immediately revoked the compromised credentials and began investigating potential impact to customers and internal systems.”

If threat actors will be able to decrypt the code signing certificates they can use them to sign malicious. The signed malicious code will evade detection because it will appear as developed by GitHub.

The company states that it has no evidence that the threat actor was able to decrypt or use these certificates.

The three compromised certificates that will be revoked on February 2, 2023, are two Digicert code signing certificates used for Windows and one Apple Developer ID certificate.

The company states that the security breach has no impact on GitHub.com or any of its other services.

“On Thursday, February 2, 2023, we will revoke the Mac & Windows signing certificates used to sign Desktop app versions 3.0.2-3.1.2 and Atom versions 1.63.0-1.63.1. Once revoked, all versions signed with these certificates will no longer function. We highly recommend updating Desktop and/or downgrading Atom before February 2 to avoid disruptions in your workflows.” concludes the notice.

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Pierluigi Paganini

(SecurityAffairs – hacking, code signing certificates)