By: Armando D’Onorio (CISSP, GSLC, GCCC), Ferrilli’s Chief Information Security Officer & Senior Consultant

VMware is urging customers to patch bugs in ESXi, Workstation, Fusion and Cloud Foundation running in on-premises or co-located settings.

The ramifications of the combined vulnerabilities are serious, especially if attackers have access to workloads inside your environments.

The patches fix a total of five (5) CVEs in those products that were disclosed during the Tianfu Cup, a Chinese security event that VMware participates in.

We’re increasing awareness for our higher education community

Knowing that most academic institutions have increased their use of VMware to help with the increase of remote work and labs from home for their employees and students.

Ferrilli is increasing the awareness and recommending that institutions pay extra close attention to failed VMware patches on their systems. Double-check that all systems have been properly patched (servers, workstations, and laptops).

**Remind all your users to patch their personal devices.**

More info about the vulnerabilities

The VMware vulnerabilities include use-after-free (UAF) bugs, double-fetch, unauthorized access, and denial of service bugs. While the individual bugs don’t reach the critical level, VMware says the combined bugs should be treated as such because they can be combined to result in higher severity.

• ESXi, Workstation and Fusion contain:
  • A UAF bug (CVE-2021-22040) in XHCI USB controller that could allow a bad actor with local admin privileges on a virtual machine to execute code as he virtual machine’s VMZ process running on the host.
  • A double-fetch bug (CVE-2021-22041) that could also lead to unauthorized code execution on the virtual machine’s VMX process running on the host.
• ESXi also contains:
  • An unauthorized access vulnerability (CVE-2021-22042) due to VMX having access to settings authorization tickets. A malicious actor with privileges in the VMX process only could access settings service running as a high priority user.
  • A Time-of-check Time-of-use bug (CVE-2021-22043) that exists in the way temporary files ae handled that could be used to escalate privileges by writing arbitrary files.
  • A slow HTTP Post denial-of-service vulnerability in rhttpproxy that could be used to create a denial-of-service condition by overwhelming rhttpproxy service with multiple requests.

For more information on workarounds and patching these vulnerabilities, read VMware’s advisory and the company’s associated blog.

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