A novel cyber threat named “Carderbee” has recently surfaced, employing an intricate software supply chain attack strategy, with a primary focus on entities situated in Hong Kong and surrounding Asian regions.
This emerging threat has been meticulously tracked by Symantec’s Threat Hunter Team, a segment of Broadcom. The attackers exploit a modified version of legitimate software, EsafeNet Cobra DocGuard Client, to disseminate a well-known backdoor called PlugX (also known as Korplug) onto targeted networks.
Remarkably, this attack utilizes malware that is signed with a legitimate Microsoft certificate, a tactic that raises concerns about the manipulation of trusted software sources. Although the use of Cobra DocGuard Client for supply chain attacks was previously highlighted by ESET in a recent Threat Report, the current campaign observed by Symantec in April 2023 reveals distinct attributes that make direct attribution to the same actor challenging. The deployment of PlugX, a tool associated with various China-linked hacking groups, adds another layer of complexity to identifying the perpetrators.
Despite the challenges in attribution, Symantec’s findings indicate that around 100 computers within the affected organizations fell victim to this attack. Notably, the Cobra DocGuard Client application was installed on roughly 2,000 endpoints, suggesting a focused approach.
The attack’s focal point appears to be the directory “csidl_system_drive\program files\esafenet\cobra docguard client\update” on infected computers, highlighting the supply chain compromise. This breach served as a conduit for deploying a downloader with a Microsoft-signed certificate, enabling the subsequent installation of PlugX from a remote server.
