CVE-2018-16851 Explained : Impact and Mitigation

A vulnerability has been discovered in Samba versions 4.0.0 and earlier, as well as versions 4.7.12, 4.8.7, and 4.9.3, leading to a denial of service when processing LDAP searches.

Understanding CVE-2018-16851

This CVE involves a vulnerability in Samba versions 4.0.0 and prior, as well as versions 4.7.12, 4.8.7, and 4.9.3, potentially resulting in a denial of service.

What is CVE-2018-16851?

The vulnerability affects Samba versions 4.0.0 and earlier, along with versions 4.7.12, 4.8.7, and 4.9.3
It can lead to a denial of service when processing LDAP searches in Samba's AD DC
The issue arises due to a memory object limitation of 256MB, causing a NULL pointer and process termination
No additional vulnerabilities are introduced, only a denial of service

The Impact of CVE-2018-16851

CVSS Score: 6.5 (Medium Severity)
Attack Vector: Network
Attack Complexity: Low
Availability Impact: High
Privileges Required: Low
Scope: Unchanged
The vulnerability can be exploited remotely without user interaction, impacting availability significantly

Technical Details of CVE-2018-16851

This section provides detailed technical information about the vulnerability.

Vulnerability Description

Samba versions 4.0.0 and earlier, as well as versions 4.7.12, 4.8.7, and 4.9.3 are susceptible to a denial of service
The issue occurs during LDAP search processing in Samba's AD DC
LDAP entries are stored in a memory object with a 256MB size limit, leading to process termination

Affected Systems and Versions

Affected Versions: 4.0.0 and earlier, 4.7.12, 4.8.7, 4.9.3
Systems running these versions of Samba are at risk of a denial of service

Exploitation Mechanism

Attackers can exploit this vulnerability remotely without requiring high privileges
By sending specially crafted LDAP search requests, they can trigger the denial of service

Mitigation and Prevention

Protecting systems from CVE-2018-16851 involves immediate actions and long-term security practices.

Immediate Steps to Take

Apply vendor-supplied patches to mitigate the vulnerability
Monitor security advisories for updates and apply them promptly

Long-Term Security Practices

Regularly update Samba software to the latest secure versions
Implement network segmentation and access controls to limit exposure

Patching and Updates

Regularly check for security updates from Samba and apply them to address vulnerabilities