This Week in Security: Terrapin, Seized Unseized, and Autospill

There’s a new SSH vulnerability, Terrapin (pdf paper), and it’s got the potential to be nasty — but only in an extremely limited circumstance. To understand the problem, we have to understand what SSH is designed to do. It replaces telnet as a tool to get a command line shell on a remote computer. Telnet send all that text in the clear, but SSH wraps it all inside a public-key encrypted tunnel. It was designed to safely negotiate an unfriendly network, which is why SSH clients are so explicit about accepting new keys, and alerting when a key has changed.


This is a companion discussion topic for the original entry at https://hackaday.com/2023/12/22/this-week-in-security-terrapin-seized-unseized-and-autospill/