CVE-2023-48795 Prefix Truncation Attack against ChaCha20-Poly1305 and Encrypt-then-MAC aka Terrapin

What is CVE-2023-48795?

CVE-2023-48795 is a medium-severity vulnerability in Apple Macos, published on 18 Dec 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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 [email protected] and (if CBC is used) the [email protected] 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.

Weakness: CWE-354

Which versions are affected by CVE-2023-48795?

10 open source packages ship an affected version, including golang.org/x/crypto, paramiko and russh. It affects 68 products.

Products include 9bis Kitty, Apache Sshd, Apache Sshj, Apple Macos, Asyncssh Project Asyncssh, Bitvise Ssh Client and 62 more.

How do I fix CVE-2023-48795?

Upgrade golang.org/x/crypto to a fixed version for your release line: 0.0.0-20231218163308-9d2ee975ef9f or 0.17.0.

Is CVE-2023-48795 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-48795 exists.

Public exploit code: 1 Nuclei template and 5 proofs of concept on GitHub.

Other vulnerabilities in Apple Macos

• CVE-2016-2563 Memory corruption in n/a Critical 9.8
• CVE-2024-23749 Command injection in n/a High 7.8
• CVE-2024-25003 Memory corruption in n/a High 7.8
• CVE-2024-25004 Memory corruption in n/a High 7.8

All Apple Macos vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2023-48795, ALSA-2024:0628, ALSA-2024:1150, AZL-32195, AZL-32196, AZL-32200 and 141 more.