rsync before 3.5.0 contains an arbitrary file read vulnerability that allows attackers to read files accessible to the rsync daemon process by exploiting symlink following in input configuration file handling including –files-from, –password-file, and filter merge files. Attackers can place a symlink at a predictable –files-from or –password-file path, or supply a –files-from path that escapes the daemon module root, to read arbitrary files accessible to the rsync process.
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.
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.