ATT&CKing TACACS+ to Pwn Your Network via a Pre-Auth RCE

TACACS+ is one of the ways large networks centralise administrative access to their equipment, alongside RADIUS and DIAMETER, and it is the one that tends to be chosen where per-command control matters. Instead of every router, switch, firewall and console server keeping its own local accounts, each device asks a TACACS+ server whether a login is allowed, at what privilege level, and often whether each individual command should be permitted. It is standard in enterprise, telco and critical infrastructure environments, usually with a single pair of servers answering for the entire fleet, which makes it an obvious target for anyone who already has a foothold on the management network and wants the rest of it.