The Kirki – Freeform Page Builder, Website Builder & Customizer plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 6.3.2 via deserialization of untrusted input . This makes it possible for authenticated attackers, with administrator-level access and above, to inject a PHP Object. No known POP chain is present in the vulnerable software, which means this vulnerability has no impact unless another plugin or theme containing a POP chain is installed on the site. If a POP chain is present via an additional plugin or theme installed on the target system, it may allow the attacker to perform actions like delete arbitrary files, retrieve sensitive data, or execute code depending on the POP chain present. By default, Editor-level users are granted FULL_ACCESS to the plugins import endpoint via the KIRKI_USERS_DEFAULT_FULL_ACCESS configuration, meaning exploitation is possible at Editor privilege level rather than being restricted to administrators alone.
Weakness
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
Potential Mitigations
- Make fields transient to protect them from deserialization.
- An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.
Related Attack Patterns
References
- https://plugins.trac.wordpress.org/browser/kirki/tags/6.3.2/includes/Ajax.php#L802
- https://plugins.trac.wordpress.org/browser/kirki/tags/6.3.2/includes/Ajax/TemplateExportImport.php#L35
- https://plugins.trac.wordpress.org/browser/kirki/tags/6.3.2/includes/ExportImport/TemplateImport.php#L963
- https://plugins.trac.wordpress.org/browser/kirki/tags/6.3.2/includes/ExportImport/TemplateImport.php#L987
- https://plugins.trac.wordpress.org/changeset/3743904/kirki/trunk/includes/ExportImport/TemplateImport.php
- https://www.wordfence.com/threat-intel/vulnerabilities/id/3c760235-ee53-4906-9e25-19df85b8f8ff?source=cve