CVE-2020-25720: Samba: check attribute access rights for ldap adds of computers
A delegated administrator who can create objects in Active Directory, can write to all attributes in that new object, including after the object is created because they own the object. This includes some security-sensitive attributes (less in Samba that in Windows).
Because these rights are due to there being no ACL at creation time and later being the nebulous 'creator owner', the implication that the delegated administrator retains significant rights may not be well understood.
Behaviour removing the implicit rights of creating users to write to all attributes is off by default in Samba and Windows (see CVE-2021-42291 )
(As mentioned in the bug, we developed some other protections for this that landed in the other CVEs, which is why this one didn't get the full security notice treatment).
The details of how to turn this protection on are at: https://support.microsoft.com/en-us/topic/kb5008383-active-directory-permissions-updates-cve-2021-42291-536d5555-ffba-4248-a60e-d6cbc849cde1
Other sources
A vulnerability was found in Samba where a delegated administrator with permission to create objects in Active Directory can write to all attributes of the newly created object, including security-sensitive attributes, even after the object's creation. This issue occurs because the administrator owns the object due to the lack of an Access Control List (ACL) at the time of creation and later being recognized as the 'creator owner.' The retained significant rights of the delegated administrator may not be well understood, potentially leading to unintended privilege escalation or security risks.
— NVD
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2020-25720?
CVE-2020-25720 is considered a medium severity vulnerability that allows delegated administrators in Samba to write to security-sensitive attributes in Active Directory.
How do I fix CVE-2020-25720?
To fix CVE-2020-25720, upgrade to the latest version of Samba where the vulnerability has been patched.
What types of systems are affected by CVE-2020-25720?
CVE-2020-25720 affects systems running Samba that allow delegated users to create and manage Active Directory objects.
What are the potential impacts of CVE-2020-25720?
The potential impacts of CVE-2020-25720 include unauthorized modification of security-sensitive attributes in Active Directory.
Who can exploit CVE-2020-25720?
CVE-2020-25720 can be exploited by delegated administrators who have permission to create objects in Active Directory.