Vulnerability · Published May 31, 2022 · Assigned by GitHub_M
CVE-2022-29245Weak private key generation in SSH.NET
Medium 6.5
In plain English
A medium-severity security flaw in SSH.NET from sshnet. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 1.5% (higher than 74% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
SSH.NET is a Secure Shell (SSH) library for .NET. In versions 2020.0.0 and 2020.0.1, during an `X25519` key exchange, the client’s private key is generated with `System.Random`. `System.Random` is not a cryptographically secure random number generator, it must therefore not be used for cryptographic purposes. When establishing an SSH connection to a remote host, during the X25519 key exchange, the private key is generated with a weak random number generator whose seed can be brute forced. This allows an attacker who is able to eavesdrop on the communications to decrypt them. Version 2020.0.2 contains a patch for this issue. As a workaround, one may disable support for `curve25519-sha256` and `curve25519-sha256@libssh.org` key exchange algorithms.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| NuGet | ssh.net | 2020.0.2 | GHSA-72p8-v4hg-v45p |
Affected products (as reported)
Weakness: CWE-338 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
References
- https://github.com/sshnet/SSH.NET/security/advisories/GHSA-72p8-v4hg-v45p x_refsource_CONFIRM
- https://github.com/sshnet/SSH.NET/commit/03c6d60736b8f7b42e44d6989a53f9b644a091fb x_refsource_MISC
- https://github.com/sshnet/SSH.NET/blob/bc99ada7da3f05f50d9379f2644941d91d5bf05a/src/Renci.SshNet/Security/KeyExchangeECCurve25519.cs#L51 x_refsource_MISC
- https://github.com/sshnet/SSH.NET/releases/tag/2020.0.2 x_refsource_MISC