The U.S. CISA has added a VMware vCenter Server Out-of-Bounds Write bug, tracked as CVE-2023-34048, to its Known Exploited Vulnerabilities (KEV) catalog.
In October 2023, VMware addressed the flaw CVE-2023-34048 with a CVSS score 9.8. On January 18, 2024, revealing that it is aware of exploitation “in the wild.”
Mandiant researchers reported that China-linked APT group UNC3886 has been exploiting vCenter Server zero-day vulnerability CVE-2023-34048. By exploiting the vulnerability, threat actors achieve administrative access within VMware ESXi Hypervisors and take over vCenter servers and virtual machines for Windows and Linux.
The highly targeted and evasive nature of this attack leads the experts to believe that the attack was carried out for cyberespionage purposes by a China-linked actor tracked as UNC3886.
In the attack investigated by Mandiant in September 2022, threat actors relied on malicious vSphere Installation Bundles (“VIBs”) to install two backdoors on the ESXi hypervisors, tracked as VIRTUALPITA and VIRTUALPIE. VIBs are collections of files that are designed to manage virtual systems, they can be used to create startup tasks, custom firewall rules, or deploy custom binaries upon the restart of an ESXi machine.
Mandiant has revealed additional techniques used by the group UNC3886 used to target multiple organizations avoiding EDR solutions.
Mandiant noticed that a VMware vmdird service crashed minutes prior to the deployment of the backdoors being deployed. The researchers also noticed that most environments where these crashes were observed had log entries preserved. However, the ‘vmdird’ core dumps were removed.
VMware’s default configurations keep core dumps for an indefinite amount of time on the system, suggesting the core dumps were purposely removed by the attacker in an attempt to cover their tracks. This vulnerability has since been patched in vCenter 8.0U2, and Mandiant recommends VMware users updating to the latest version of vCenter to account for this vulnerability seeing exploitation in the wild.”
CISA orders federal agencies to fix this vulnerability by February 12, 2024.
