CVE-2019-3842 : Vulnerability Insights and Analysis

A vulnerability was found in systemd prior to v242-rc4, where pam_systemd fails to properly sanitize the environment when utilizing the XDG_SEAT variable. This flaw allows attackers to manipulate the XDG_SEAT environment variable, potentially leading to the execution of unauthorized commands against polkit policies.

Understanding CVE-2019-3842

This CVE pertains to a vulnerability in systemd that could be exploited by attackers to execute unauthorized commands.

What is CVE-2019-3842?

In systemd before v242-rc4, the pam_systemd component does not adequately sanitize the environment, specifically the XDG_SEAT variable. This oversight enables attackers to manipulate the XDG_SEAT variable, potentially executing commands against polkit policies using the "allow_active" element instead of "allow_any".

The Impact of CVE-2019-3842

The vulnerability has a CVSS v3.0 base score of 4.5, with a medium severity rating. The impact includes low confidentiality, integrity, and availability impacts, with low privileges required for exploitation in a local attack vector scenario.

Technical Details of CVE-2019-3842

This section provides more technical insights into the vulnerability.

Vulnerability Description

The flaw in systemd allows attackers to manipulate the XDG_SEAT environment variable, potentially executing unauthorized commands against polkit policies.

Affected Systems and Versions

Product: systemd
Vendor: The systemd Project
Versions Affected: v242-rc4

Exploitation Mechanism

Attackers can exploit this vulnerability by manipulating the XDG_SEAT environment variable, enabling the execution of unauthorized commands against polkit policies.

Mitigation and Prevention

Protecting systems from CVE-2019-3842 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update systemd to version v242-rc4 or later to mitigate the vulnerability.
Monitor for any unusual activities related to the XDG_SEAT environment variable.

Long-Term Security Practices

Implement strict environment sanitization practices in software development.
Regularly review and update security configurations to prevent similar vulnerabilities.

Patching and Updates

Apply patches and updates provided by the vendor to address the vulnerability effectively.