We found a new compression side-channel attack against SSH: if you use port forwarding with terminal sessions, a web attacker+eavesdropper can recover a sudo pwd in a few hundred trials. There is only one compression context for all channels. Accepted at CCS 26, preprint: arxiv.org/abs/2609.07709
arxiv.org
Crossing the Streams: SSH Plaintext Recovery via a Common Compression Context in Multiplexed Channels
SSH is the standard protocol for secure remote administration of servers. At the transport layer, SSH uses the Binary Packet Protocol (BPP) for encrypted and authenticated communication. Above this, t...
