CVE-2017-20208

The RegistrationMagic – Custom Registration Forms, User Registration, Payment, and User Login plugin for WordPress is vulnerable to PHP Object Injection in all versions up to 3.7.9.3 (exclusive) via deserialization of untrusted input from the is_expired_by_date() function. This makes it possible for unauthenticated attackers to inject a PHP Object. The additional presence of a POP chain allows attackers to fetch a remote file and install it on the site.

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

• https://cwe.mitre.org/data/definitions/586.html

References

• https://plugins.trac.wordpress.org/changeset/1733274/custom-registration-form-builder-with-submission-manager
• https://www.wordfence.com/blog/2017/10/3-zero-day-plugin-vulnerabilities-exploited-wild/
• https://www.wordfence.com/threat-intel/vulnerabilities/id/c2b79193-f8fc-4ea2-8973-fe292cfb926b?source=cve