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Samba Password Change Vulnerability

A vulnerability has been discovered in the Samba 4 Active Directory domain controller (AD DC) which allows authenticated users to change passwords for other accounts, including privileged and administrative accounts.
Threat ID:
CC-2160
Category:
Threat Severity:
Medium
Threat Vector:
Published:
22 March 2018 12:00 AM
Report a cyber attack: call 0300 303 5222 or email [email protected]

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This article no longer conforms to NHS Digital's standards for cyber alerts, and may contain outdated or inaccurate information. Use of this information contained in this page is at your own risk

Summary

A vulnerability has been discovered in the Samba 4 Active Directory domain controller (AD DC) which allows authenticated users to change passwords for other accounts, including privileged and administrative accounts.

Threat details

The Lightweight Directory Access Protocol (LDAP) server on a Samba 4 AD DC incorrectly validates some password modifications against the 'Change Password' privilege, but then carries out a password reset. The change does not produce any useful audit logs.

If privileged accounts are compromised, then an attacker can read or modify any data on the domain.

Remediation steps

Type Step
  • Monitor password changes using the pwdLastSet and msDS-KeyVersionNumber attributes, e.g. ldbsearch -H /usr/local/samba/private/sam.ldb objectclass=user pwdLastSet msDS-KeyVersionNumber
  • Upgrade Samba to the latest version.
  • Reset any compromised accounts and audit their activity.

Last edited: 17 February 2020 12:54 pm