Security researchers have discovered a vulnerability in the SSH cryptographic network protocol that could allow an attacker to downgrade the connection's security by truncating the extension negotiation message.
Terrapin is a prefix truncation attack targeting the SSH protocol.
Aside from downgrading the SSH connection's security by forcing it to use less secure client authentication algorithms, the attack can also be used to exploit vulnerabilites in SSH implementations.
To pull of a Terrapin attack the attacker must already be able to intercept and modify the data sent from the client or server to the remote peer, they pointed out, making it more feasible to be performed on the local network.
More details about their findings can be found in their paper and on a dedicated website.
The researchers have contacted nearly 30 providers of various SSH implementations and shared their research so they may provide fixes before publication.
Vendors/maintainers of affected implementations, applications and Linux distros have been pushing out fixes: AsyncSSH, LibSSH, OpenSSH, PuTTY, SUSE, and others.
Administrators can also use the Terrapin Vulnerability Scanner to determine whether an SSH client or server is vulnerable.
This Cyber News was published on www.helpnetsecurity.com. Publication date: Tue, 19 Dec 2023 11:13:04 +0000