CVE-2021-3769 : Exploit Details and Defense Strategies

A vulnerability in

pygmalion

,

pygmalion-virtualenv

, and

refined

themes within Oh My Zsh allows attackers to exploit specially-crafted branch names. This can lead to the execution of arbitrary commands on affected systems.

Understanding CVE-2021-3769

This CVE refers to a critical OS Command Injection vulnerability in specific themes of Oh My Zsh, impacting user-supplied strings when printing them to the terminal. The vulnerability resides in the git information processing that can be manipulated by malicious actors.

What is CVE-2021-3769?

The vulnerability in the affected themes results from the use of

print -P

on user-provided branch names in the terminal. By crafting a malicious branch name, an attacker can inject and execute arbitrary commands on the targeted system.

The Impact of CVE-2021-3769

The impact of this CVE is rated as HIGH based on CVSS v3.1 scoring, affecting the confidentiality, integrity, and availability of the system. The attack complexity is considered HIGH, and no special privileges are required for exploitation.

Technical Details of CVE-2021-3769

This section outlines the specifics of the vulnerability, including the affected systems and the exploitation mechanism employed by attackers.

Vulnerability Description

The vulnerability arises from the way certain themes in Oh My Zsh process and print user-supplied branch names. By using specially-crafted branch names, attackers can inject and execute arbitrary commands on the affected systems.

Affected Systems and Versions

The vulnerability impacts Oh My Zsh versions less than

b3ba9978

, specifically affecting the

pygmalion

,

pygmalion-virtualenv

, and

refined

themes.

Exploitation Mechanism

Attackers can exploit this vulnerability by creating a git repository with a malicious branch name containing commands to be executed. Upon switching to this branch with the affected themes enabled, the injected commands are executed on the system.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-3769, immediate steps should be taken to secure the affected systems and prevent potential exploitation by malicious actors.

Immediate Steps to Take

Users are advised to update Oh My Zsh to the fixed version (b3ba9978) to address the vulnerability. Additionally, refrain from using untrusted branch names or themes that may trigger the injection of arbitrary commands.

Long-Term Security Practices

Implementing secure coding practices and maintaining up-to-date versions of software components can help prevent similar vulnerabilities in the future. Regular security audits and educating users about safe practices are essential.

Patching and Updates

Ensure that systems are regularly patched with the latest security updates provided by the software vendor to mitigate the risks associated with known vulnerabilities.