Vulnerability in the VMware Directory Service (vmdir) (CVE-2020-3952) – VMSA-2020-0006

On April 9th, 2020 VMSA-2020-0006 was published. This advisory documents a critical severity sensitive information disclosure vulnerability identified by CVE-2020-3952.

Affected versions

The vulnerability received a CVSSv3 score of 10 out of 10. Which means this is a very serious security issue. Response matrix is VMSA-2020-0006.

How I can check it?

Additional Documentation for VMSA-2020-0006: Determining if a vCenter 6.7 deployment w/embedded or external Platform Services Controller (PSC) is affected by CVE-2020-3952 (78543)

Virtual Appliance Log File Location: /var/log/vmware/vmdird/vmdird-syslog.log or in /var/log/vmware/vmdird/vmdird-syslog.log.*.gz

zgrep "ACL" /var/log/vmware/vmdird/*.gz
/var/log/vmware/vmdird/vmdird-syslog.log.x.gz:2020-xx-xxTxxxxxx+00:00 info vmdird t@xxxxxx: ACL MODE: Legacy

Notes from KB:

  • In order to be affected by CVE-2020-3952, a deployment must meet 2 criteria. First, it must be a 6.7 deployment prior to 6.7u3f. Second, it must be running in legacy ACL mode.
  • Because the ACL MODE: Legacy log entry is only thrown at vmdir startup,  it is possible that it will be absent due to log file rollover even on affected deployments.
  • The ACL MODE: Legacy log entry will still be thrown after upgrading to 6.7u3f and/or 7.0 even though CVE-2020-3952 is resolved in these releases.

Path it NOW ! – PoC was published !

It is recommended to block any access over the LDAP port (389) except for administrative use.

Clean installations of vCenter Server 6.7 (embedded or external PSC) are not affected.

vCenter Server 6.7 (embedded or external PSC) prior to 6.7u3f is affected by CVE-2020-3952 if it was upgraded from a previous release line such as 6.0 or 6.5.

Path it ASAP because:

  • On April 15th, 2020 was relased information about How to reconstructed the faulty code flow that led to this vulnerability.

Author: Daniel Micanek

Senior Service Architect, SAP Platform Services Team at TietoEVRY | vExpert ⭐⭐ | vExpert NSX | VCIX-DCV | VCAP-NV Design | VCAP-DCV Design+Deploy | VCP-DCV/NV/CMA | NCIE-DP | OCP | Azure Solutions Architect | Certified Kubernetes Administrator (CKA)