CVE-2021-28041 Explained : Impact and Mitigation

A detailed analysis of CVE-2021-28041, a vulnerability found in ssh-agent in OpenSSH before version 8.5, with potential impact and mitigation strategies.

Understanding CVE-2021-28041

CVE-2021-28041 is a vulnerability in ssh-agent in OpenSSH before version 8.5, involving a double free issue that could be exploited under specific conditions.

What is CVE-2021-28041?

CVE-2021-28041 in OpenSSH before 8.5 consists of a double free bug that could be significant in certain uncommon situations like unconstrained agent-socket access on a legacy operating system or forwarding an agent to an attacker-controlled host.

The Impact of CVE-2021-28041

The impact of this vulnerability includes the potential for unauthorized access to sensitive information, compromising system integrity, and enabling attackers to execute malicious activities within the affected systems.

Technical Details of CVE-2021-28041

This section details the technical aspects of CVE-2021-28041, including the vulnerability description, affected systems and versions, and exploitation mechanism.

Vulnerability Description

The vulnerability involves a double free issue in ssh-agent in OpenSSH, which could be leveraged by attackers in specific scenarios to gain unauthorized access or perform malicious activities.

Affected Systems and Versions

OpenSSH versions before 8.5 are affected by CVE-2021-28041. Systems with unconstrained agent-socket access on legacy operating systems are particularly at risk.

Exploitation Mechanism

Attackers could exploit this vulnerability by gaining access to the agent-socket in legacy systems or forwarding an agent to a host under their control, leading to unauthorized access and potential system compromise.

Mitigation and Prevention

This section outlines the steps to mitigate the risks associated with CVE-2021-28041, including immediate actions and long-term security practices.

Immediate Steps to Take

Users are advised to update their OpenSSH installations to version 8.5 or later, monitor agent-socket access, and restrict forwarding of agents to untrusted hosts to prevent exploitation.

Long-Term Security Practices

Implementing secure access controls, regular security updates, and monitoring agent-related activities can enhance the long-term security posture of systems to prevent similar vulnerabilities.

Patching and Updates

Regularly apply patches provided by OpenSSH to address security issues, stay informed about security advisories, and follow best practices for maintaining secure SSH configurations.