A critical Terrapin attack has emerged, posing a threat to nearly 11 million internet-exposed SSH servers. Developed by researchers from Ruhr University Bochum, this attack targets the SSH protocol, affecting both clients and servers. The Terrapin attack manipulates sequence numbers during the handshake process, compromising the integrity of SSH channels, particularly when using encryption modes like ChaCha20-Poly1305 or CBC with Encrypt-then-MAC. To execute the Terrapin attack, threat actors need to be in an adversary-in-the-middle position, allowing interception and modification of the handshake exchange.
Security threat monitoring platform Shadowserver issued a report revealing the widespread vulnerability, affecting approximately 52% of all scanned SSH servers on the public web. The report highlights that nearly 11 million SSH servers, identified by unique IP addresses, are susceptible to Terrapin attacks. While not all instances are immediately at risk, the sheer volume of vulnerable systems provides threat actors with a significant pool to choose from. The highest number of vulnerable systems were identified in the United States, followed by China, Germany, Russia, Singapore, and Japan.
The Terrapin attack could have a broad impact, compromising the integrity of SSH connections and potentially leading to security breaches. Shadowserver’s report emphasizes the need for vigilance and the importance of checking SSH clients and servers for susceptibility to Terrapin. Researchers from Ruhr University Bochum have provided a vulnerability scanner to assist in identifying and mitigating the risk posed by this critical SSH vulnerability.
