CVE-2022-32746 Overview
A use-after-free vulnerability was discovered in the Samba AD LDAP server. The AD DC database audit logging module can access LDAP message values that have been freed by a preceding database module, resulting in a use-after-free condition. This vulnerability is only exploitable when modifying certain privileged attributes, such as userAccountControl.
Critical Impact
Authenticated attackers with network access can exploit this use-after-free vulnerability to potentially cause integrity and availability impacts on the Samba AD Domain Controller.
Affected Products
- Samba (multiple versions)
Discovery Timeline
- 2022-08-25 - CVE-2022-32746 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2022-32746
Vulnerability Analysis
This vulnerability (CWE-416: Use After Free) exists within the Samba Active Directory Domain Controller's LDAP server implementation. The flaw occurs in the interaction between the database audit logging module and preceding database modules during LDAP operations.
When certain privileged LDAP attributes are modified, a race condition can occur where the audit logging module attempts to access LDAP message values that have already been deallocated by a preceding database module. This creates a use-after-free condition where the audit logging module references memory that is no longer valid.
The vulnerability requires authenticated access with sufficient privileges to modify sensitive AD attributes such as userAccountControl. This attribute controls critical user account properties including account status, password requirements, and delegation settings, making it a high-value target for attackers who have already gained a foothold in the environment.
Root Cause
The root cause is improper memory management between the database audit logging module and preceding database modules in the Samba AD LDAP server. The audit logging module fails to properly synchronize with other modules regarding the lifecycle of LDAP message values, leading to a situation where freed memory is subsequently accessed.
Attack Vector
The attack vector is network-based and requires low privileges (authenticated access). An attacker with valid credentials and the ability to modify privileged AD attributes can trigger this vulnerability through specially crafted LDAP modification requests targeting attributes like userAccountControl. The vulnerability affects the integrity and availability of the Samba AD Domain Controller, potentially allowing an attacker to corrupt data or cause a denial of service condition.
The exploitation requires the attacker to:
- Authenticate to the Samba AD LDAP server
- Have permissions to modify privileged attributes
- Submit LDAP modification requests that trigger the audit logging path
- Time the request to exploit the race condition between database modules
Detection Methods for CVE-2022-32746
Indicators of Compromise
- Unexpected modifications to privileged AD attributes such as userAccountControl
- Samba AD Domain Controller crashes or service restarts without clear cause
- Anomalous LDAP modification requests in audit logs targeting sensitive attributes
- Memory corruption errors in Samba logs related to the audit logging module
Detection Strategies
- Monitor Samba AD DC logs for signs of memory corruption or unexpected crashes
- Implement LDAP query logging to track modifications to privileged attributes
- Deploy endpoint detection rules to identify exploitation attempts targeting Samba services
- Enable verbose auditing on the Samba AD DC to capture detailed operation logs
Monitoring Recommendations
- Configure alerts for unusual volumes of LDAP modification operations
- Monitor for repeated authentication attempts followed by attribute modification requests
- Track changes to userAccountControl and other privileged AD attributes
- Implement baseline monitoring for Samba service stability and restart frequency
How to Mitigate CVE-2022-32746
Immediate Actions Required
- Apply the latest Samba security patches immediately
- Review and restrict permissions for modifying privileged AD attributes
- Enable enhanced logging on Samba AD Domain Controllers
- Consider implementing network segmentation to limit access to AD services
Patch Information
Samba has released security updates to address this vulnerability. Administrators should update to the latest patched version of Samba. For detailed patch information and affected versions, refer to the Samba CVE-2022-32746 Security Advisory.
Gentoo Linux users should also review the Gentoo GLSA 2023-09-06 for distribution-specific guidance.
Workarounds
- Restrict LDAP modification permissions to only essential administrative accounts
- Implement network-level access controls to limit which systems can communicate with the Samba AD DC
- Consider temporarily disabling AD DC audit logging if patching cannot be performed immediately (note: this reduces visibility into AD operations)
- Monitor for exploitation attempts while preparing to apply patches
# Check current Samba version
samba --version
# After updating, restart Samba services
systemctl restart samba-ad-dc
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
