Saint Terrapin, Who Quietly Trimmed the Handshake

Patron of SSH connections, sequence numbers, and anyone who thinks an encrypted channel must be an intact one.

Life

On 18 December 2023 the Terrapin researchers showed a flaw in the SSH protocol: a man in the middle could remove certain packets at the start of the connection, especially from the extension negotiation, without being noticed. In this way some security defences were silently downgraded or switched off. It affected OpenSSH before 9.6 and many other products.

Prayer

O Saint Terrapin, who slips packets from the start of the conversation, let our handshakes count every message from the first. Amen.

How to celebrate

Celebrated by updating SSH clients and servers to the version with the 'strict kex' countermeasure.

Who doesn't count the first packets pays for the last.

Technical record

Disclosed on: December 18 2023
CVE: CVE-2023-48795 CVE-2023-46445 CVE-2023-46446 CVE-2024-41909
CVSS: 6.8
Product: Apache Software Foundation · Apache MINA SSHD

The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other products, allows remote attackers to bypass integrity checks such that some packets are omitted (from the extension negotiation message), and a client and server may consequently end up with a connection for which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because the SSH Binary Packet Protocol (BPP), implemented by these extensions, mishandles the handshake phase and mishandles use of sequence numbers. For example, there is an effective attack against SSH's use of ChaCha20-Poly1305 (and CBC with Encrypt-then-MAC). The bypass occurs in chacha20-poly1305@openssh.com and (if CBC is used) the -etm@openssh.com MAC algorithms. This also affects Maverick Synergy Java SSH API before 3.1.0-SNAPSHOT, Dropbear through 2022.83, Ssh before 5.1.1 in Erlang/OTP, PuTTY before 0.80, AsyncSSH before 2.14.2, golang.org/x/crypto before 0.17.0, libssh before 0.10.6, libssh2 through 1.11.0, Thorn Tech SFTP Gateway before 3.4.6, Tera Term before 5.1, Paramiko before 3.4.0, jsch before 0.2.15, SFTPGo before 2.5.6, Netgate pfSense Plus through 23.09.1, Netgate pfSense CE through 2.7.2, HPN-SSH through 18.2.0, ProFTPD before 1.3.8b (and before 1.3.9rc2), ORYX CycloneSSH before 2.3.4, NetSarang XShell 7 before Build 0144, CrushFTP before 10.6.0, ConnectBot SSH library before 2.2.22, Apache MINA sshd through 2.11.0, sshj through 0.37.0, TinySSH through 20230101, trilead-ssh2 6401, LANCOM LCOS and LANconfig, FileZilla before 3.66.4, Nova before 11.8, PKIX-SSH before 14.4, SecureCRT before 9.4.3, Transmit5 before 5.10.4, Win32-OpenSSH before 9.5.0.0p1-Beta, WinSCP before 6.2.2, Bitvise SSH Server before 9.32, Bitvise SSH Client before 9.33, KiTTY through 0.76.1.13, the net-ssh gem 7.2.0 for Ruby, the mscdex ssh2 module before 1.15.0 for Node.js, the thrussh library before 0.35.1 for Rust, and the Russh crate before 0.40.2 for Rust.

Sources: terrapin-attack.com

Canonized by Pope CitrixBleed I

Saint Terrapin, Who Quietly Trimmed the Handshake

Life

Prayer

How to celebrate

Technical record

Related saints

Sharing the feast day

Same year: 2023