The ‘AMP for WP – Accelerated Mobile Pages’ plugin for WordPress is vulnerable to a privilege escalation attack. Updating the plugin to version ‘0.9.97.20’ fixes the flaw.

Updated November 19: The original posting of this blog credited WebARX security with the discovery of the vulnerability. This was incorrect as this initial discovery was made by plugin developer Sybre Waaijer. The text below has been corrected, and the reference links now include the wpvulndb page.

Background

Following the discovery of a critical vulnerability in the WP GDPR Compliance Plugin, another critical WordPress plugin vulnerability was discovered this week in the popular AMP for WP plugin by Sybre Waaijer. The plugin adds support for Google Accelerated Mobile Pages (AMP), a mobile site acceleration tool, to any WordPress site that has it installed.

Older versions of the plugin are vulnerable to a privilege escalation flaw, which allows WordPress site users of any level to make administrative API calls.

Analysis

WordPress allows all users to make AJAX API calls to manage or invoke various functions they may need to manage their site. However, the older version of this plugin didn’t include a wpnonce check to verify account permissions of the currently logged in user, effectively opening admin API access to anyone with a login for a site.

Admin access for WordPress allows for ad placement, custom HTML, and manual WordPress plugin uploads. From an outsider attack perspective, basic or even guest users are now a potential vector for admin access.

Proof of Concept

Source: WebARX Security

Solution

An updated version of the plugin is available via automatic updates through WordPress. Users can also manually download the plugin update here.

Identifying affected systems

Plugin 101841 will detect any WordPress plugins that are out of date, which includes the AMP for WP plugin, but doesn’t reflect the criticality of this specific issue.

A list of Tenable plugins to identify this vulnerability will appear here as they’re released.

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