TERRAPIN ATTACKS CAN DOWNGRADE SECURITY OF OPENSSH CONNECTIONS

Summary from the TLDR InfoSec newsletter

A group of researchers have discovered a novel attack against SSH connections that can downgrade the security of the connection by truncating negotiation messages. The attack requires the attacker to have established a man-in-the-middle position and the SSH connection to be secured with either ChaCha20-Poly1305 or CBC with Encrypt-then-MAC. The researchers have released a scanner to determine if servers are vulnerable.