SSH Weak MAC Algorithms Enabled Security Misconfiguration Scanner

SSH Weak MAC Algorithms are commonly found in systems for secure shell access, particularly in Unix-like operating systems. These systems are used globally by both individuals and enterprises for secure remote management of network devices and infrastructure. System administrators rely on SSH to safely configure servers and update systems remotely. The use of weak MAC algorithms in SSH can undermine the integrity and security of these connections. Such configurations might be present in older systems or improperly managed setups. It is essential for maintaining the security of sensitive data and communications.

The vulnerability arises when weak Message Authentication Code (MAC) algorithms are permitted in SSH configurations. These algorithms are used to verify the data integrity and origin in SSH connections. However, when these algorithms are outdated or weak, it leaves the connection susceptible to attacks such as replay attacks and unauthorized access. This vulnerability indicates poor default configurations or out-of-date security practices. The consequence of using weak MACs can lead to breaches of confidential information transmitted over SSH connections. Strengthening MAC algorithms is crucial to ensure robust security measures are in place.

Technical examination of this vulnerability typically reveals the use of weak MACs such as "hmac-md5", "hmac-md5-96", or "hmac-sha1-96". These are susceptible to cryptographic attacks, thereby endangering encrypted communications. The vulnerable endpoint in this case is the SSH service, commonly running on port 22, and the parameter involves MAC algorithm selection. Admins should ensure their configurations use stronger MACs like "hmac-sha2-256". Using updated SSH clients and configurations can mitigate this vulnerability effectively. Affected systems can easily be scanned for these weak settings to ensure compliance with best practices.

Potential exploits could allow attackers to inject malicious data into the SSH communications, resulting in unauthorized actions. Once the data integrity is compromised, sensitive data could be intercepted or manipulated. This could lead to entire server infrastructures being vulnerable to data theft or modification. In worst-case scenarios, it can permit attackers to gain deeper access into otherwise secure networks. Such vulnerability exploitation could also lead to reputational damage and legal issues for mishandling sensitive information.

REFERENCES

• https://www.tenable.com/plugins/nessus/71049