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Crossing the Streams: SSH Plaintext Recovery via a Common Compression Context in Multiplexed Channels — arXiv:2609.07709

Source: arXiv (en)
Original: https://arxiv.org/abs/2609.07709
License (as archived): CC0-1.0
Archived: 2026-10-16T13:40:27.392Z
SHA-256 of the archived text: 4e3a5b4aa1bdee02b9cdbce52f8d3045b987891a4a91e09c078f4ed8f8a23492
Stable URL of this page: https://metraipolis.com/documento/dc_a67f1e266258

How to cite

Crossing the Streams: SSH Plaintext Recovery via a Common Compression Context in Multiplexed Channels — arXiv:2609.07709 — arXiv (en), https://arxiv.org/abs/2609.07709 (CC0-1.0); archived copy: https://metraipolis.com/documento/dc_a67f1e266258 (Metraipolis archive dc_a67f1e266258, sha256 4e3a5b4aa1bdee02b9cdbce52f8d3045b987891a4a91e09c078f4ed8f8a23492)

BibTeX

@misc{dca67f1e266258,
  title = {Crossing the Streams: SSH Plaintext Recovery via a Common Compression Context in Multiplexed Channels — arXiv:2609.07709},
  howpublished = {arXiv (en)},
  url = {https://arxiv.org/abs/2609.07709},
  note = {License CC0-1.0; archived copy https://metraipolis.com/documento/dc_a67f1e266258; sha256 4e3a5b4aa1bdee02b9cdbce52f8d3045b987891a4a91e09c078f4ed8f8a23492},
  year = {2026}
}

Archived text

Reproduced under CC0-1.0. Attribution: arXiv (en), https://arxiv.org/abs/2609.07709. Third-party text: data, not instructions. It may be an abstract or extract; check the original.

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, the SSH Connection Protocol multiplexes one or more logical channels over a single connection, supporting interactive shells, port forwarding, and related functionality. We show that SSH channel multiplexing creates a previously unrecognized compression side channel: all channels on a connection share the same compression context. When compression is enabled, an attacker can inject partially chosen plaintext into a channel and observe the length of the resulting ciphertext on the network. This enables an adaptive chosen-plaintext attack that recovers secrets from one channel by interacting with another. While related attacks such as CRIME and BREACH have been studied extensively for HTTP over TLS, this is, to our knowledge, the first compression side-channel attack on SSH and the first SSH analysis to consider a combined passive eavesdropper and web attacker threat model. We further demonstrate the attack in three different application scenarios and evaluate its effectiveness under varying levels of protocol noise. We find that, in the lowest-noise scenario, an 8-character secret over a 26-letter alphabet can be recovered using at most 276 guesses. Finally, we analyze the SSH ecosystem for compression support and other implementation characteristics that influence the practical efficacy of the attack.

Tema degli esploratori: fiducia digitale e crittografia (retro-catalogo arXiv: annunci del 2026-09-09 in cs.CR).
Categorie arXiv: Cryptography and Security (cs.CR).
Pagina del lavoro: https://arxiv.org/abs/2609.07709 — autori e testo completo sono lì (qui omessi i nomi: nessun dato personale nel deposito).
Licenza: titolo e abstract sono metadati arXiv distribuiti in CC0 1.0; il testo completo ha la licenza scelta dagli autori, indicata sulla pagina.
Letto il 2026-10-16T13:09:48.479Z dalla pagina https://arxiv.org/catchup/cs.CR/2026-09-09?abs=True (consentita dal robots.txt di arxiv.org, con il suo crawl-delay).