CVE-2023-38408 : Security Advisory and Response

OpenSSH before version 9.3p2 with PKCS#11 feature in ssh-agent has a vulnerability, CVE-2023-38408, allowing remote code execution via an untrustworthy search path when forwarding the agent to an attacker's system. It is crucial to understand the impact, technical details, and mitigation of this security issue.

Understanding CVE-2023-38408

This section will delve into the vulnerability, its impact, affected systems, exploitation mechanism, and ways to mitigate and prevent potential risks.

What is CVE-2023-38408?

The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 is affected by an insufficiently trustworthy search path. This flaw enables remote code execution when forwarding the agent to a system controlled by an attacker. Notably, code in the /usr/lib directory may not be safe for loading into ssh-agent. This issue is a result of an incomplete fix for a past CVE (CVE-2016-10009).

The Impact of CVE-2023-38408

The vulnerability poses a severe risk of allowing remote attackers to execute arbitrary code on affected systems. Successful exploitation could lead to a complete compromise of the system and unauthorized access to sensitive information.

Technical Details of CVE-2023-38408

To secure systems from potential threats posed by this CVE, it is essential to understand the specifics regarding the vulnerability, affected systems, and the exploitation procedure.

Vulnerability Description

The vulnerability in OpenSSH's PKCS#11 feature allows attackers to execute malicious code remotely by exploiting the untrustworthy search path in ssh-agent when forwarded to their system.

Affected Systems and Versions

The issue affects OpenSSH versions before 9.3p2 that utilize the PKCS#11 feature in ssh-agent.

Exploitation Mechanism

Remote code execution occurs when an attacker gains control over an OpenSSH agent forwarded to a system they control. By manipulating the search path, the attacker can execute arbitrary code on the compromised system.

Mitigation and Prevention

Protecting systems from CVE-2023-38408 requires immediate actions and the establishment of robust security practices to prevent future vulnerabilities.

Immediate Steps to Take

Upon discovery of this vulnerability, users are advised to update affected OpenSSH installations to version 9.3p2 or later. Furthermore, administrators should avoid forwarding ssh-agents to untrusted systems.

Long-Term Security Practices

Implementing a least-privilege access policy, regular security audits, and monitoring SSH agent forwarding can enhance system security and mitigate risks associated with remote code execution.

Patching and Updates

Regularly check for security updates and patches provided by OpenSSH to address known vulnerabilities and ensure the safety of systems.