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Bug 920280 (CVE-2023-48795) - [Tracker] Terrapin Vulnerability
Summary: [Tracker] Terrapin Vulnerability
Status: CONFIRMED
Alias: CVE-2023-48795
Product: Gentoo Security
Classification: Unclassified
Component: Vulnerabilities (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: Gentoo Security
URL: https://terrapin-attack.com/
Whiteboard:
Keywords: Tracker
Depends on: 920293 920299 920304 920385 920421 920682 921290 920291 920292
Blocks:
  Show dependency tree
 
Reported: 2023-12-18 17:03 UTC by Christopher Fore
Modified: 2024-01-03 14:34 UTC (History)
5 users (show)

See Also:
Package list:
Runtime testing required: ---


Attachments

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Description Christopher Fore 2023-12-18 17:03:28 UTC
CVE-2023-48795 (https://terrapin-attack.com/):

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 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, and PuTTY before 0.80; and there could be effects on Bitvise SSH through 9.31, AsyncSSH through 2.14.1, libssh through 0.10.5, and golang.org/x/crypto through 2023-12-17.
Comment 1 David Sardari 2023-12-18 19:13:13 UTC
I've used the following command to mitigate on the client side:

sed -i "1i Ciphers -$(ssh -Q cipher | grep -e chacha20-poly1305@openssh.com -e -cbc | paste -d, -s -)" ~/.ssh/config

In my case, the following line got added before the first line of the file:

Ciphers -3des-cbc,aes128-cbc,aes192-cbc,aes256-cbc,chacha20-poly1305@openssh.com
Comment 2 Hanno Böck gentoo-dev 2023-12-19 07:40:07 UTC
CVE-2023-46445 and CVE-2023-46446 are issues in AsyncSSH, which Gentoo has not packaged, so I believe they are irellevant here.

Only CVE-2023-48795 refers to the Terrapin vulnerability in the SSH protocol itself that affects pretty much every SSH implementation.