CVE-2018-6553 : Security Advisory and Response

The CUPS AppArmor profile mistakenly restricted the dnssd backend due to the use of hard links, potentially allowing a local attacker to break out of confinement in affected Ubuntu versions.

Understanding CVE-2018-6553

This CVE involves a vulnerability in the CUPS AppArmor profile that could be exploited by a local attacker to escape sandbox confinement.

What is CVE-2018-6553?

The vulnerability arises from the incorrect confinement of the dnssd backend in the CUPS AppArmor profile, enabling a potential sandbox bypass due to the use of hard links.

The Impact of CVE-2018-6553

The vulnerability affects various versions of Ubuntu, including 18.04 LTS, 17.10, 16.04 LTS, and 14.04 LTS, prior to specific versions mentioned in the descriptions.

Technical Details of CVE-2018-6553

This section provides more in-depth technical insights into the vulnerability.

Vulnerability Description

The CUPS AppArmor profile incorrectly confines the dnssd backend, allowing a local attacker to exploit the issue and escape confinement.

Affected Systems and Versions

Ubuntu 18.04 LTS: versions prior to 2.2.7-1ubuntu2.1
Ubuntu 17.10: versions prior to 2.2.4-7ubuntu3.1
Ubuntu 16.04 LTS: versions prior to 2.1.3-4ubuntu0.5
Ubuntu 14.04 LTS: versions prior to 1.7.2-0ubuntu1.10

Exploitation Mechanism

The vulnerability can be exploited by a local attacker with access to the system to break out of the confinement imposed by the CUPS AppArmor profile.

Mitigation and Prevention

To address CVE-2018-6553, it is crucial to take immediate steps and implement long-term security practices.

Immediate Steps to Take

Update CUPS to the patched versions specified for each affected Ubuntu release.
Monitor system logs for any suspicious activities related to CUPS.
Restrict access to vulnerable systems to trusted users only.

Long-Term Security Practices

Regularly update and patch all software and applications on the system.
Implement least privilege access controls to limit the impact of potential security breaches.

Patching and Updates

Apply the necessary security updates provided by Ubuntu for CUPS to mitigate the vulnerability effectively.