CVE-2018-16841 Explained : Impact and Mitigation

Samba versions 4.7.12, 4.8.7, and 4.9.3 are vulnerable to a denial of service due to a double-free memory issue in the Key Distribution Center (KDC) component.

Understanding CVE-2018-16841

Samba is susceptible to a denial of service vulnerability when configured to accept smart-card authentication.

What is CVE-2018-16841?

Samba's KDC mistakenly calls the function talloc_free() twice on the same memory area, leading to a denial of service if the principal in a validly signed certificate does not match the principal in the AS-REQ.

The Impact of CVE-2018-16841

CVSS Base Score: 5.7 (Medium)
Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Availability Impact: High

Technical Details of CVE-2018-16841

Samba's vulnerability details and affected systems.

Vulnerability Description

Samba's KDC incorrectly handles smart-card authentication, causing a double-free memory issue.

Affected Systems and Versions

Product: Samba
Versions: 4.7.12, 4.8.7, 4.9.3

Exploitation Mechanism

The vulnerability occurs when the KDC processes authentication requests with mismatched principals.

Mitigation and Prevention

Protecting systems from CVE-2018-16841.

Immediate Steps to Take

Apply vendor patches and updates promptly.
Disable smart-card authentication if not essential.

Long-Term Security Practices

Regularly monitor security advisories for Samba.
Implement network segmentation to limit the impact of potential attacks.
Conduct security training for users on safe authentication practices.

Patching and Updates

Update Samba to versions that address the double-free memory issue.