Critical VMware Vulnerability

THE THREAT

On October 20th, 2020, VMware announced a critical vulnerability affecting several VMware products [1]. CVE-2020-3992 allows for Remote Code Execution (RCE). If exploited, a threat actor with access to the management network, can execute remote code without authentication on vulnerable machines. The vulnerability is rated accordingly at a criticality score of 9.8 out of 10.

Although exploitation of CVE-2020-3992 has not been identified at this time, eSentire has determined that exploitation is likely in the near future, given the severity of this vulnerability. Organizations are strongly recommended to deploy security patches before exploitation is identified in the wild.

What we’re doing about it

• eSentire security teams continue to track this topic for additional details and detection opportunities
• MVS has local plugins to identify CVE-2020-3992

What you should do about it

• After performing a business impact review, apply the official security patches [2]
  • If patching is not possible at this time, apply the work arounds provided by VMware [3]

Additional information

CVE-2020-3992 is a Use After Free vulnerability. The vulnerability resides in the processing of SLP messages; the lack of validation of objects allows a threat actor to execute code in the context of the SLP daemon [1].

In order to exploit this vulnerability, a threat actor would need pervious access to the network and port 427 on an ESXi machine. Authentication is not required for successful exploitation.

Affected Products:

• ESXi version 7.0
• ESXi version 6.7
• ESXi version 6.5
• VMware Cloud Foundation (ESXi) version 4.x & 3.x

References:

[1] https://www.zerodayinitiative.com/advisories/ZDI-20-1269/

[2] https://www.vmware.com/security/advisories/VMSA-2020-0023.html

[3] https://kb.vmware.com/s/article/76372