North Korean state-sponsored threat actors, identified as Diamond Sleet and Onyx Sleet, have been exploiting a critical remote code execution vulnerability in JetBrains TeamCity, a widely-used DevSecOps tool.
Furthermore, the vulnerability, CVE-2023-42793, allows unauthenticated attackers to execute arbitrary code on TeamCity on-premises servers, enabling them to steal sensitive data, source code, service secrets, and private keys. This poses a significant security threat, given that TeamCity’s on-premises CI/CD server is utilized by over 30,000 users, including prominent organizations like Nike, Citibank, and Ubisoft. This incident underscores North Korean hackers’ persistent efforts to target various sectors and highlights the need for enhanced cybersecurity measures.
Diamond Sleet, one of the North Korean threat actors, is known for its focus on espionage, data theft, financial gains, and network disruption. It has a history of targeting media, IT services, and defense-related entities globally.
Additionally, Diamond Sleet previously targeted security researchers and weaponized open-source software, demonstrating its evolving tactics. Onyx Sleet, another North Korean actor, primarily targets defense and IT service organizations in South Korea, the United States, and India. It employs in-house tools to establish persistent access to victim environments and avoid detection.
In their attack analysis, Diamond Sleet used a backdoor known as “ForestTiger” to compromise TeamCity servers. They employed PowerShell to download malicious payloads and a configuration file from compromised infrastructure. Onyx Sleet, on the other hand, created a new user account named “krtbgt” on compromised systems, which was used for system discovery and other malicious activities.
Microsoft has identified the attackers using a proxy tool called HazyLoad to establish a persistent connection between compromised hosts and attacker-controlled infrastructure. These revelations serve as a stark reminder of the evolving cyber threats and the importance of proactive security measures.
