Chinese hackers quietly exploited a VMware zero-day for two years

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Chinese state-sponsored hackers known as UNC3886 have been abusing a zero-day vulnerability in VMware and Fortinet devices for years, experts have revealed.

A report from Mandiant claims the group used the flaw to deploy malware, steal credentials, and ultimately exfiltrate sensitive data.

The flaw in question is tracked as CVE-2023-34048. It carries a severity score of 9.8/10 (critical), and is described as an out-of-bounds write flaw that allows remote code execution to attackers with access to vCenter Server. The patch was released in late October 2023. 

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"UNC3886 has a track record of utilizing zero-day vulnerabilities to complete their mission without being detected, and this latest example further demonstrates their capabilities," Mandiant explained in the report. With the help of CVE-2023-34048, UNC3886 was allowed to enumerate all ESXi hosts and guest virtual machines on a vulnerable system, and then pull cleartext “vpxuser” credentials for the hosts. The next step was to install VIRTUALPITA and VIRTUALPIE malware, which granted direct access to the compromised endpoints.

From that point, the attackers abused a separate flaw, CVE-2023-20867 (severity score 3.9), to run arbitrary commands and pull sensitive information from the devices. 

VMware urges vCenter Server users to apply the latest patch immediately.

The last time we heard of UNC3886 was in September 2022, when researchers spotted the group compromising VMware’s ESXi hypervisors to gain access to virtual machines and spy on businesses in the west. Back then, the group was observed installing two malicious programs on bare-metal hypervisors, using vSphere Installation Bundles - the same ones as in this attack. Furthermore, they discovered a unique malware/dropper dubbed VirtualGate.

Unlike this attack, in which a zero-day was being abused, in the previous incident the group simply used admin-level access to the ESXi hypervisors to install their tools.

Via TheHackerNews

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Sead is a seasoned freelance journalist based in Sarajevo, Bosnia and Herzegovina. He writes about IT (cloud, IoT, 5G, VPN) and cybersecurity (ransomware, data breaches, laws and regulations). In his career, spanning more than a decade, he’s written for numerous media outlets, including Al Jazeera Balkans. He’s also held several modules on content writing for Represent Communications.