ImageMagick before 7.1.2-30 and 6.9.13-55 contains a time-of-check-time-of-use (TOCTOU) vulnerability in the video decoder that allows attackers to bypass path policy write restrictions via symlink swaps. An attacker can replace a symlink between policy validation (check-time) and the file write operation (use-time) to write to policy-denied locations.
Weakness
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Imagemagick | Imagemagick | * | 6.9.13-55 (excluding) |
| Imagemagick | Imagemagick | 7.0.0-0 (including) | 7.1.2-30 (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
- https://cwe.mitre.org/data/definitions/132.html
- https://cwe.mitre.org/data/definitions/17.html
- https://cwe.mitre.org/data/definitions/35.html
- https://cwe.mitre.org/data/definitions/76.html