CVE-2018-1057 in Samba
Summary
by MITRE
On a Samba 4 AD DC the LDAP server in all versions of Samba from 4.0.0 onwards incorrectly validates permissions to modify passwords over LDAP allowing authenticated users to change any other users' passwords, including administrative users and privileged service accounts (eg Domain Controllers).
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Analysis
by VulDB Data Team • 02/21/2023
This vulnerability exists within the Lightweight Directory Access Protocol implementation of Samba 4 Active Directory Domain Controllers, specifically affecting all versions from 4.0.0 through the affected releases. The flaw represents a critical authorization bypass that fundamentally undermines the security model of Active Directory environments relying on Samba implementations. The vulnerability stems from improper validation of access controls during password modification operations, allowing any authenticated user to manipulate the passwords of arbitrary accounts within the domain without proper authorization. This represents a severe privilege escalation vector that directly violates the principle of least privilege and could enable attackers to gain persistent access to critical administrative accounts. The vulnerability is classified under CWE-284 which specifically addresses improper access control mechanisms, and aligns with ATT&CK technique T1078 for valid accounts and T1550 for use of stolen credentials, as it enables unauthorized password changes that can then be leveraged for further compromise.
The technical exploitation of this vulnerability occurs through LDAP bind operations that authenticate users to the Samba AD DC, followed by password modification requests that bypass the expected permission checks. When an authenticated user submits a password change request over LDAP, the system fails to properly validate whether the requesting user has sufficient privileges to modify the target account's password. This validation failure affects both standard user accounts and privileged accounts including domain controllers, service accounts, and administrative users. The flaw exists in the LDAP server component's access control list processing logic, where it incorrectly grants modification rights to any authenticated user regardless of their role or the target account's security attributes.
The operational impact of this vulnerability is catastrophic for organizations utilizing Samba 4 as their Active Directory implementation, as it provides attackers with the ability to silently compromise any account within the domain. Once exploited, attackers can change passwords for domain administrators, privileged service accounts, and domain controller accounts without detection, potentially leading to complete domain compromise. The vulnerability affects organizations with Samba 4 AD DC deployments across various environments including enterprise networks, cloud infrastructures, and hybrid deployments. The stealth nature of the attack makes it particularly dangerous as password changes typically do not generate alerts in standard monitoring systems, allowing attackers to maintain persistent access while remaining undetected. This vulnerability can be exploited in both initial compromise scenarios and lateral movement phases of attacks, making it a critical target for remediation.
Organizations should immediately apply security patches from the Samba project to address this vulnerability, as no reliable workarounds exist for the underlying access control flaw. The patch addresses the improper validation logic in the LDAP server component and restores proper access control enforcement for password modification operations. System administrators should conduct comprehensive audits of all Samba 4 AD DC implementations to verify the vulnerability status and monitor for any unauthorized password changes. Security monitoring should be enhanced to detect anomalous password modification patterns, particularly those involving privileged accounts. Additionally, organizations should implement multi-factor authentication for privileged accounts, enforce strict password policies, and conduct regular security assessments of their Active Directory implementations. The vulnerability highlights the importance of proper access control validation in directory services and the critical need for regular security updates in enterprise infrastructure components.