BianLian Group Exploits Jetbrains TeamCity Bugs In Ransomware Attacks
March 11, 2024 – Published on Security Affairs
BianLian ransomware group was spotted exploiting vulnerabilities in JetBrains TeamCity software in recent attacks.
Researchers from GuidePoint Security noticed, while investigating a recent attack linked to the BianLian ransomware group, that the threat actors gained initial access to the target by exploiting flaws in a TeamCity server.
The BianLian ransomware emerged in August 2022, the malware was employed in attacks against organizations in various industries, including manufacturing, media and entertainment, and healthcare.
In January 2023, security firm Avast released a free decryptor for the BianLian ransomware to allow victims of the malware to recover locked files.
The threat actors behind the attack investigated by the researchers exploited TeamCity flaws CVE-2024-27198 or CVE-2023-42793 to gain initial access to the victim’s environment. The attackers created new users on the vulnerable server and executed malicious commands for post-exploitation and lateral movement.
Then the threat actor discovered two build servers in the target environment from which they expanded their foothold in the victim organization and pivoted for further exploitation.
The researchers noticed that the BianLian group failed multiple attempts to execute their custom GO backdoor, then pivoted to living off the land and leveraged a PowerShell implementation of their backdoor.
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