rsync before 3.5.0 contains a path traversal vulnerability that allows a malicious sender to write files outside the intended destination directory tree by crafting relative paths with symlink components in –relative mode. The make_path() function follows symlinks pointing outside the destination tree while creating intermediate directories without verifying that created paths remain within the destination boundary, enabling arbitrary file writes on the receivers filesystem.
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.
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