A UNIX symbolic link following issue in the jailer component in Firecracker version v1.13.1 and earlier and 1.14.0 on Linux may allow a local host user with write access to the pre-created jailer directories to overwrite arbitrary host files via a symlink attack during the initialization copy at jailer startup, if the jailer is executed with root privileges.
To mitigate this issue, users should upgrade to version v1.13.2 or 1.14.1 or above.
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 |
|---|---|---|---|
| Firecracker | Amazon | * | 1.13.2 (excluding) |
| Firecracker | Amazon | 1.14.0 (including) | 1.14.0 (including) |
| Firecracker | Amazon | 1.14.0-dev (including) | 1.14.0-dev (including) |
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.