CVE-2019-12571

A vulnerability in the London Trust Media Private Internet Access (PIA) VPN Client v0.9.8 beta (build 02099) for macOS could allow an authenticated, local attacker to overwrite arbitrary files. When the client initiates a connection, the XML /tmp/pia-watcher.plist file is created. If the file exists, it will be truncated and the contents completely overwritten. This file is removed on disconnect. An unprivileged user can create a hard or soft link to arbitrary files owned by any user on the system, including root. This creates a denial of service condition and possible data loss if leveraged by a malicious local user.

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

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

References

• https://github.com/mirchr/security-research/blob/master/vulnerabilities/PIA/CVE-2019-12571.txt