Impact
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:<profile> and --security=selinux:<label> 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.
In addition, a bug in the detection of selinux support in Apptainer's suid mode means that --security selinux:<label> flags may not be applied, even in the absence of an attack. In that case a warning message is emitted indicating that selinux is unavailable, but the warning may be may be overlooked, mis-interpreted, or not seen when apptainer is run from a script or other tool. Failure to apply requested restrictions should result in a fatal error rather than just a warning message.
Patches
Ineffective write of selinux process labels is addressed via an update to the containers/selinux dependency in apptainer/apptainer#3226. That update brings in the upstream fix for GHSA-cgrx-mc8f-2prm which was for a different but related vulnerability.
Ineffective write of apparmor process profiles is addressed in commit 4313b42.
Failure to detect apparmor / selinux support, when --security flags are provided, is made an error rather than a warning in commit 82f1790.
Workarounds
There are no known workarounds, other than to define system-wide apparmor / selinux policy for Apptainer itself. This would apply to all containers, not just those run with the --security flags, and could impact the operation of Apptainer itself.
References
Thanks to Sylabs for finding this issue, fixing it in GHSA-wwrx-w7c9-rf87 which was easy to import into Apptainer, and disclosing it early to the Apptainer project for a coordinated release.
The related upstream runc disclosure which inspired the investigation is GHSA-cgrx-mc8f-2prm.
References
dtrudg Finder
Impact
In Apptainer versions less than 1.4.5, a container can disable two of the forms of the little used
--securityoption, in particular the forms--security=apparmor:<profile>and--security=selinux:<label>which otherwise put restrictions on operations that containers can do. The--securityoption 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.In addition, a bug in the detection of selinux support in Apptainer's suid mode means that
--security selinux:<label>flags may not be applied, even in the absence of an attack. In that case a warning message is emitted indicating that selinux is unavailable, but the warning may be may be overlooked, mis-interpreted, or not seen when apptainer is run from a script or other tool. Failure to apply requested restrictions should result in a fatal error rather than just a warning message.Patches
Ineffective write of selinux process labels is addressed via an update to the containers/selinux dependency in apptainer/apptainer#3226. That update brings in the upstream fix for GHSA-cgrx-mc8f-2prm which was for a different but related vulnerability.
Ineffective write of apparmor process profiles is addressed in commit 4313b42.
Failure to detect apparmor / selinux support, when --security flags are provided, is made an error rather than a warning in commit 82f1790.
Workarounds
There are no known workarounds, other than to define system-wide apparmor / selinux policy for Apptainer itself. This would apply to all containers, not just those run with the
--securityflags, and could impact the operation of Apptainer itself.References
Thanks to Sylabs for finding this issue, fixing it in GHSA-wwrx-w7c9-rf87 which was easy to import into Apptainer, and disclosing it early to the Apptainer project for a coordinated release.
The related upstream runc disclosure which inspired the investigation is GHSA-cgrx-mc8f-2prm.
References