Impact
Insecure permissions on temporary directories used in explicit and implicit container build operations.
When a Singularity command that results in a container build operation is executed, it is possible for a user with access to the system to read the contents of the image during the build. Additionally, if the image contains a world-writable file or directory, it is possible for a user to inject arbitrary content into the running build, which in certain circumstances may enable arbitrary code execution during the build and/or when the built container is run.
Patches
This issue is addressed in Singularity 3.6.3.
All users are advised to upgrade to 3.6.3.
Workarounds
The issue is mitigated if TMPDIR is set to a location that is only accessible to the user, as any subdirectories directly under TMPDIR cannot then be accessed by others. However, this is difficult to enforce so it is not recommended to rely on this as a mitigation.
For more information
General questions about the impact of the advisory / changes made in the 3.6.0 release can be asked in the:
Any sensitive security concerns should be directed to: security@sylabs.io
See our Security Policy here: https://sylabs.io/security-policy
References
Impact
Insecure permissions on temporary directories used in explicit and implicit container build operations.
When a Singularity command that results in a container build operation is executed, it is possible for a user with access to the system to read the contents of the image during the build. Additionally, if the image contains a world-writable file or directory, it is possible for a user to inject arbitrary content into the running build, which in certain circumstances may enable arbitrary code execution during the build and/or when the built container is run.
Patches
This issue is addressed in Singularity 3.6.3.
All users are advised to upgrade to 3.6.3.
Workarounds
The issue is mitigated if
TMPDIRis set to a location that is only accessible to the user, as any subdirectories directly underTMPDIRcannot then be accessed by others. However, this is difficult to enforce so it is not recommended to rely on this as a mitigation.For more information
General questions about the impact of the advisory / changes made in the 3.6.0 release can be asked in the:
Any sensitive security concerns should be directed to: security@sylabs.io
See our Security Policy here: https://sylabs.io/security-policy
References