CVE-2019-15793 : Security Advisory and Response

A modification known as shiftfs in the Linux kernel series for Ubuntu introduced a vulnerability that could allow a local attacker to bypass access control permissions.

Understanding CVE-2019-15793

This CVE involves mishandling file-system uid/gid with namespaces in shiftfs.

What is CVE-2019-15793?

In the Ubuntu 5.0 and 5.3 kernel series, a modification called shiftfs introduced an issue where user/group ids were erroneously translated, potentially allowing a local attacker to bypass access control permissions.

The Impact of CVE-2019-15793

The vulnerability could be exploited by a local attacker to circumvent discretionary access control permissions, potentially leading to unauthorized access to sensitive information.

Technical Details of CVE-2019-15793

This section provides detailed technical information about the CVE.

Vulnerability Description

The vulnerability in shiftfs allowed for the unintended use of ids in the lower filesystem due to incorrect translations, potentially enabling a local attacker to bypass access control permissions.

Affected Systems and Versions

Shiftfs in the Linux kernel version 5.3.0-11.12
Shiftfs in the Linux kernel version 5.0.0-35.38

Exploitation Mechanism

The vulnerability could be exploited by a local attacker to manipulate file-system uid/gid mappings, potentially gaining unauthorized access to sensitive data.

Mitigation and Prevention

Protecting systems from CVE-2019-15793 is crucial to maintaining security.

Immediate Steps to Take

Apply patches provided by Ubuntu to address the vulnerability.
Monitor for any unauthorized access or unusual system behavior.

Long-Term Security Practices

Regularly update the Linux kernel and system software to prevent known vulnerabilities.
Implement least privilege access controls to limit the impact of potential security breaches.

Patching and Updates

Stay informed about security updates from Ubuntu and apply them promptly to mitigate the risk of exploitation.