Apptainer is an open source container platform. In Apptainer versions less than 1.4.5, a container can disable two of the forms of the little used –security option, in particular the forms –security=apparmor: and –security=selinux: which otherwise put restrictions on operations that containers can do. The –security option has always been mentioned in Apptainer documentation as being a feature for the root user, although these forms do also work for unprivileged users on systems where the corresponding feature is enabled. Apparmor is enabled by default on Debian-based distributions and SElinux is enabled by default on RHEL-based distributions, but on SUSE it depends on the distribution version. This vulnerability is fixed in 1.4.5.
Weakness
The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Apptainer | Lfprojects | * | 1.4.5 (excluding) |
Potential Mitigations
- Follow the principle of least privilege when assigning access rights to entities in a software system.
- Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.
Related Attack Patterns
References
- https://github.com/apptainer/apptainer/commit/4313b42717e18a4add7dd7503528bc15af905981
- https://github.com/apptainer/apptainer/commit/82f17900a0c31bc769bf9b4612d271c7068d8bf2
- https://github.com/apptainer/apptainer/pull/3226
- https://github.com/apptainer/apptainer/security/advisories/GHSA-j3rw-fx6g-q46j
- https://github.com/opencontainers/runc/security/advisories/GHSA-cgrx-mc8f-2prm
- https://github.com/sylabs/singularity/security/advisories/GHSA-wwrx-w7c9-rf87