Arbitrary Options Update in Welcome Software Publishing WordPress Plugin

Detection Guidance

This vulnerability can be detected by monitoring XML-RPC requests to the WordPress site, specifically looking for calls to the nc.setOption method.

You can use network traffic inspection tools or web server logs to identify XML-RPC requests that invoke nc.setOption.

For example, using command-line tools like grep on server logs to search for nc.setOption calls:

• grep -i 'nc.setOption' /path/to/wordpress/wp-content/debug.log
• grep -i 'nc.setOption' /var/log/apache2/access.log

Additionally, monitoring for unusual changes to WordPress options such as default_role being set to 'administrator' can indicate exploitation.

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Executive Summary

The Welcome Software Publishing plugin for WordPress has a vulnerability in all versions up to and including 0.0.31. This vulnerability arises because the nc_setOption() function, accessible via the nc.setOption XML-RPC method, lacks a proper authorization check. Although it verifies user credentials, it does not check if the user has the necessary permissions to manage options.

As a result, authenticated users with Subscriber-level access or higher can update arbitrary WordPress options through XML-RPC requests. This can be exploited to change the default user role to 'administrator' and create a new administrator account, leading to full privilege escalation and potential site takeover.

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Impact Analysis

This vulnerability can have severe impacts including unauthorized privilege escalation and complete site takeover. An attacker with only Subscriber-level access can exploit this flaw to gain administrator privileges by modifying WordPress options and creating new administrator accounts.

Once an attacker has administrator access, they can control the entire WordPress site, potentially leading to data breaches, defacement, malware injection, or disruption of services.

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Mitigation Strategies

Immediate mitigation steps include disabling the XML-RPC interface or restricting access to it to trusted users only.

Updating the Welcome Software Publishing plugin to a version later than 0.0.31, where this vulnerability is fixed, is critical.

If an update is not immediately available, consider applying custom patches to add proper authorization checks in the nc_setOption() function.

Also, review and reset any suspicious WordPress options, especially the default_role option, and audit user accounts for unauthorized administrator creation.

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