cbcvebase.
CVE-2020-3952
published 2020-04-10

CVE-2020-3952: Under certain conditions, vmdir that ships with VMware vCenter Server, as part of an embedded or external Platform Services Controller (PSC), does not…

PriorityP194critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
KEVITWEXPLOITInitial access
CISA Known Exploited Vulnerabilitydue 2022-05-03
Exploited in the wild
EPSS
90.38%
99.8th percentile
Under certain conditions, vmdir that ships with VMware vCenter Server, as part of an embedded or external Platform Services Controller (PSC), does not correctly implement access controls.

Affected

1 ranges
VendorProductVersion rangeFixed in
vmwarevcenter_server

Detection & IOCsextracted from sources · hover to see the quote

port389
url/sdk/
otherSOAPAction: urn:vim25/6.5
othercn=Users,dc=vsphere,dc=local
othercn=Administrators,cn=Builtin,dc=vsphere,dc=local
bytes
\x30\x05\x02\x01\x04\x42\x00
sigma
matchers: words: ['RetrieveServiceContentResponse', 'urn:vim'] in HTTP response body with Content-Type: text/xml and status 200
  • Detect unauthenticated (anonymous-bind) LDAP connections to port 389 on vCenter Server, especially those attempting to add or modify users in cn=Users,dc=vsphere,dc=local or modify membership of cn=Administrators,cn=Builtin,dc=vsphere,dc=local.
  • Monitor for LDAP Add (opcode 0x68) and Modify (opcode 0x66) requests to vmdir on port 389 without prior successful authentication, particularly targeting vsphere.local directory objects.
  • Alert on LDAP bind responses returning result code 0x31 (invalidCredentials) followed immediately by LDAP Add or Modify operations — the exploit proceeds even after a failed bind.
  • Detect HTTP POST requests to /sdk/ with SOAPAction 'urn:vim25/6.5' and response body containing 'RetrieveServiceContentResponse' as a reconnaissance indicator against vCenter.
  • Vulnerability only affects vCenter Server 6.7 instances that were upgraded from a previous release (6.0 or 6.5); clean 6.7 installs are not affected. Scope detection efforts accordingly.
  • Monitor for new user creation in vsphere.local LDAP directory (objectClass: user under cn=Users,dc=vsphere,dc=local) with attribute vmwPasswordNeverExpires set to True, which is a characteristic of exploit-created accounts.
  • ·The exploit requires network access to port 389 (LDAP) on the vCenter Server or PSC. Restricting network access to vmdir/LDAP from untrusted networks reduces exposure.
  • ·The Metasploit module also supports authenticated operation via BIND_DN and LDAPPassword options, meaning the same module can be used for both exploitation and legitimate admin tasks — authenticated use should not be treated as benign without context.
  • ·The exploit default timeout is 5 seconds; scanners or IDS with very short connection timeouts may miss slow exploit attempts.

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv2.06.8MEDIUMAV:N/AC:M/Au:N/C:P/I:P/A:P
vulncheck9.8CRITICAL
cisa9.8CRITICAL
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