Date: Mon, 6 Nov 2023 00:08:10 +0100 From: Solar Designer <solar@...nwall.com> To: oss-security@...ts.openwall.com Cc: Pietro Albini <pietro@...troalbini.org> Subject: Re: CVE-2022-46176: Cargo does not check SSH host keys Hi, On Tue, Jan 10, 2023 at 05:45:06PM +0100, Pietro Albini wrote: > The Rust Security Response WG was notified that Cargo did not perform SSH host > key verification when cloning indexes and dependencies via SSH. An attacker > could exploit this to perform man-in-the-middle (MITM) attacks. > > This vulnerability has been assigned CVE-2022-46176. In the distros thread leading to the above oss-security posting, Pietro Albini also wrote: > Note that while investigating this we discovered that the underlying library > Cargo uses for git operations, libgit2, does not perform SSH host key checking > either. We've been coordinating with them, and they'll also release a fix on > 2023-01-10. I think the libgit2 issue was never brought to oss-security, so I am passing its mention to here now. Also per that thread, CVE-2022-46176 is only for the Cargo issue. libgit2 was supposed to get its own CVE, but no one in the thread knew whether they actually did. I don't know whether libgit2 was actually fixed on that date as planned. Alexander P.S. I'm quoting the rest of the oss-security posting I'm "replying" to below, for context since it's been a while. On Tue, Jan 10, 2023 at 05:45:06PM +0100, Pietro Albini wrote: > The Rust Security Response WG was notified that Cargo did not perform SSH host > key verification when cloning indexes and dependencies via SSH. An attacker > could exploit this to perform man-in-the-middle (MITM) attacks. > > This vulnerability has been assigned CVE-2022-46176. > > ## Overview > > When an SSH client establishes communication with a server, to prevent MITM > attacks the client should check whether it already communicated with that > server in the past and what the server's public key was back then. If the key > changed since the last connection, the connection must be aborted as a MITM > attack is likely taking place. > > It was discovered that Cargo never implemented such checks, and performed no > validation on the server's public key, leaving Cargo users vulnerable to MITM > attacks. > > ## Affected Versions > > All Rust versions containing Cargo before 1.66.1 are vulnerable. > > Note that even if you don't explicitly use SSH for alternate registry indexes > or crate dependencies, you might be affected by this vulnerability if you have > configured git to replace HTTPS connections to GitHub with SSH (through git's > [`url.<base>.insteadOf`] setting), as that'd cause you to clone the > crates.io index through SSH. > > ## Mitigations > > We will be releasing Rust 1.66.1 today, 2023-01-10, changing Cargo to check the > SSH host key and abort the connection if the server's public key is not already > trusted. We recommend everyone to upgrade as soon as possible. > > Patch files for Rust 1.66.0 are also available [here] for custom-built > toolchains. > > For the time being Cargo will not ask the user whether to trust a server's > public key during the first connection. Instead, Cargo will show an error > message detailing how to add that public key to the list of trusted keys. Note > that this might break your automated builds if the hosts you clone dependencies > or indexes from are not already trusted. > > ## Acknowledgments > > Thanks to the Julia Security Team for disclosing this to us according to our > [security policy]! > > We also want to thank the members of the Rust project who contributed to fixing > this issue. Thanks to Eric Huss and Weihang Lo for writing and reviewing the > patch, Pietro Albini for coordinating the disclosure and writing this advisory, > and Josh Stone, Josh Triplett and Jacob Finkelman for advising during the > disclosure. > > : https://git-scm.com/docs/git-config#Documentation/git-config.txt-urlltbasegtinsteadOf > : https://github.com/rust-lang/wg-security-response/tree/main/patches/CVE-2022-46176 > : https://www.rust-lang.org/policies/security
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