Since early October 2023, Microsoft has observed two North Korean nation-state threat actors – Diamond Sleet and Onyx Sleet – exploiting CVE-2023-42793, a remote-code execution vulnerability affecting multiple versions of JetBrains TeamCity server. TeamCity is a continuous integration/continuous deployment (CI/CD) application used by organizations for DevOps and other software development activities. In past operations, Diamond Sleet and other North Korean threat actors have successfully carried out software supply chain attacks by infiltrating build environments.
Given this, Microsoft assesses that this activity poses a particularly high risk to organizations who are affected. JetBrains has released an update to address this vulnerability and has developed a mitigation for users who are unable to update to the latest software version.