CVE-2024-38531

Nix is a package manager for Linux and other Unix systems that makes package management reliable and reproducible. A build process has access to and can change the permissions of the build directory. After creating a setuid binary in a globally accessible location, a malicious local user can assume the permissions of a Nix daemon worker and hijack all future builds. This issue was patched in version(s) 2.23.1, 2.22.2, 2.21.3, 2.20.7, 2.19.5 and 2.18.4.

Weakness

A product inherits a set of insecure permissions for an object, e.g. when copying from an archive file, without user awareness or involvement.

Affected Software

Potential Mitigations

• Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
• Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

References

• https://github.com/NixOS/nix/pull/10501
• https://github.com/NixOS/nix/security/advisories/GHSA-q82p-44mg-mgh5