CVE-2020-25720 in Samba
Summary
by MITRE • 11/17/2024
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.
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Analysis
by VulDB Data Team • 07/05/2025
This vulnerability exists within the Samba implementation of Active Directory integration where a critical access control flaw allows delegated administrators to maintain excessive privileges over newly created objects. The issue stems from the absence of proper Access Control List enforcement during object creation, creating a window where administrators can manipulate security-sensitive attributes even after object instantiation. The vulnerability specifically affects scenarios where delegated administrators possess permissions to create objects in Active Directory but lack proper privilege restrictions that should normally govern attribute modifications. This flaw represents a significant deviation from standard security practices where object ownership should be properly constrained by ACL mechanisms at creation time.
The technical implementation flaw occurs because Samba's Active Directory integration does not properly enforce access control restrictions during the object creation phase, allowing administrators to retain elevated privileges that should be revoked upon object creation. This creates a persistent security risk where the creator owner attribute remains active and grants comprehensive rights to modify all object attributes, including those critical for security posture. The vulnerability manifests when a delegated administrator creates an object without proper ACL enforcement, resulting in the object being owned by the creator with full modification rights. This design oversight enables potential privilege escalation scenarios where administrators can modify security-sensitive attributes that should normally be restricted to specific privileged roles.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential security breaches through unauthorized modification of critical Active Directory attributes. Attackers or malicious administrators could exploit this weakness to modify object permissions, change security descriptors, or manipulate other sensitive attributes that control access to resources within the domain. The retained rights of the delegated administrator may not be immediately recognized or understood by system administrators, creating a latent security risk that could be exploited over time. This vulnerability particularly affects environments where delegated administration is commonly used, as the risk exists for any object creation operation performed by administrators with creation permissions.
Mitigation strategies should focus on implementing proper access control enforcement during object creation, ensuring that ACLs are properly applied and that creator owner privileges are appropriately constrained. Organizations should review and restrict delegated administrator permissions to prevent excessive rights during object creation, implementing principle of least privilege controls. The implementation of proper auditing and monitoring for object creation activities can help detect unauthorized modifications to security-sensitive attributes. System administrators should also consider implementing additional controls such as attribute-level permissions and access reviews to ensure that newly created objects do not inherit excessive privileges. This vulnerability aligns with CWE-284 which addresses improper access control and ATT&CK technique T1078 which covers valid accounts and privilege escalation through legitimate access rights. Regular security assessments and proper configuration management should be implemented to prevent unauthorized access to critical Active Directory attributes and maintain proper security boundaries.