oss-security - Re: CVE-2023-48795: Prefix Truncation Attacks in SSH Specification (Terrapin Attack)

Follow @Openwall on Twitter for new release announcements and other news

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date: Wed, 20 Dec 2023 09:41:07 +0100
From: Marcus Meissner <meissner@...e.de>
To: oss-security@...ts.openwall.com
Subject: Re: CVE-2023-48795: Prefix Truncation Attacks in SSH
 Specification (Terrapin Attack)

On Tue, Dec 19, 2023 at 01:31:03PM -0800, Alan Coopersmith wrote:
> On 12/18/23 08:08, Fabian Bäumer wrote:
> > ### Mitigations
> > 
> > To mitigate this protocol vulnerability, OpenSSH suggested a so-called
> > "strict kex" which alters the SSH handshake to ensure a
> > Man-in-the-Middle attacker cannot introduce unauthenticated messages as
> > well as convey sequence number manipulation across handshakes. Support
> > for strict key exchange has been added to a variety of SSH
> > implementations, including OpenSSH itself, PuTTY, libssh, and more.
> > 
> > **Warning: To take effect, both the client and server must support this
> > countermeasure.**
> 
> Open source projects I see have implemented this already are:
> 
> - AsyncSSH 2.14.2:
>   https://asyncssh.readthedocs.io/en/latest/changes.html#release-2-14-2-18-dec-2023
> 
> - Dropbear git:
>   https://github.com/mkj/dropbear/commit/6e43be5c7b99dbee49dc72b6f989f29fdd7e9356
> 
> - Erlang ssh 5.1.1:
>   https://www.erlang.org/doc/apps/ssh/notes
> 
> - golang.org/x/crypto 0.17.0:
>   https://groups.google.com/g/golang-announce/c/qA3XtxvMUyg
> 
> - libssh 0.10.6 and 0.9.8:
>   https://www.libssh.org/2023/12/18/libssh-0-10-6-and-libssh-0-9-8-security-releases/
> 
> - libssh2 git:
>   https://github.com/libssh2/libssh2/issues/1290
>   https://github.com/libssh2/libssh2/pull/1291
> 
> - OpenSSH 9.6:
>   https://www.openssh.com/txt/release-9.6
> 
> - Paramiko 3.4.0:
>   https://www.paramiko.org/changelog.html#3.4.0
> 
> - PuTTY 0.80:
>   https://lists.tartarus.org/pipermail/putty-announce/2023/000037.html
> 
> - russh 0.40.2:
>   https://github.com/warp-tech/russh/releases/tag/v0.40.2
> 
> - SFTPGo 2.5.6:
>   https://github.com/drakkan/sftpgo/releases/tag/v2.5.6
> 
> - ssh2 [node.js/npm] 1.15.0:
>   https://github.com/mscdex/ssh2/commits/v1.15.0
> 
> - Tera Term 5.1:
>   https://github.com/TeraTermProject/teraterm/releases/tag/v5.1
> 
> - Thrussh 0.35.1:
>   https://pijul.org/posts/2023-12-18-thrussh-cve/
> 
> There's also some open bugs against these open source projects that are not yet handled:
> 
> - Apache Mina:
>   https://github.com/apache/mina-sshd/issues/445
> 
> - ProFTPD (mod_sftp):
>   https://github.com/proftpd/proftpd/issues/1760
> 
> - SSHJ:
>   https://github.com/hierynomus/sshj/issues/916

some more

Jsch (Java SSH): release 0.2.15 fixes it https://github.com/mwiede/jsch/releases/tag/jsch-0.2.15

Also apache-sshd and trilead-ssh2 as Java SSH implementations are
affected.

tinyssh affected, has a ticket open.

rubygem-net-ssh also affected.

The rust ecosystem has a ssh crate which fixates its used libssh version. "libssh2-sys", so
crates and binaries referencing will need updates.

python Twisted has an SSH stack too, but no chacha or etm macs so far. 

Ciao, Marcus

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.