The Spam protection, Anti-Spam, FireWall by CleanTalk plugin for WordPress is vulnerable to unauthorized Arbitrary Plugin Installation due to an authorization bypass via reverse DNS (PTR record) spoofing on the checkWithoutToken function in all versions up to, and including, 6.71. This makes it possible for unauthenticated attackers to install and activate arbitrary plugins which can be leveraged to achieve remote code execution if another vulnerable plugin is installed and activated. Note: This is only exploitable on sites with an invalid API key.
Weakness
The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.
Extended Description
Since DNS names can be easily spoofed or misreported, and it may be difficult for the product to detect if a trusted DNS server has been compromised, DNS names do not constitute a valid authentication mechanism. When the product performs a reverse DNS resolution for an IP address, if an attacker controls the DNS server for that IP address, then the attacker can cause the server to return an arbitrary hostname. As a result, the attacker may be able to bypass authentication, cause the wrong hostname to be recorded in log files to hide activities, or perform other attacks. Attackers can spoof DNS names by either (1) compromising a DNS server and modifying its records (sometimes called DNS cache poisoning), or (2) having legitimate control over a DNS server associated with their IP address.
Potential Mitigations
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/142.html
- https://cwe.mitre.org/data/definitions/275.html
- https://cwe.mitre.org/data/definitions/73.html
- https://cwe.mitre.org/data/definitions/89.html
References
- https://plugins.trac.wordpress.org/browser/cleantalk-spam-protect/trunk/lib/Cleantalk/ApbctWP/RemoteCalls.php#L69
- https://plugins.trac.wordpress.org/browser/cleantalk-spam-protect/trunk/lib/Cleantalk/Common/Helper.php#L64
- https://plugins.trac.wordpress.org/changeset/3454488/cleantalk-spam-protect#file473
- https://www.wordfence.com/threat-intel/vulnerabilities/id/cb603be6-4a12-49e1-b8cc-b2062eb97f16?source=cve