CVE-2021-24950 in Insight Core Plugin
Summary
by MITRE • 03/14/2022
The Insight Core WordPress plugin through 1.0 does not have any authorisation and CSRF checks in the insight_customizer_options_import (available to any authenticated user), does not validate user input before passing it to unserialize(), nor sanitise and escape it before outputting it in the response. As a result, it could allow users with a role as low as Subscriber to perform PHP Object Injection, as well as Stored Cross-Site Scripting attacks
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Analysis
by VulDB Data Team • 03/16/2022
The CVE-2021-24950 vulnerability resides within the Insight Core WordPress plugin version 1.0 and earlier, presenting a critical security flaw that undermines the integrity of WordPress installations. This vulnerability stems from the plugin's failure to implement proper authorization controls and Cross-Site Request Forgery protections within its insight_customizer_options_import functionality. The flaw allows any authenticated user, regardless of their role level, to exploit this endpoint and potentially execute arbitrary code on the target system.
The technical implementation of this vulnerability involves multiple security weaknesses that compound to create a dangerous attack surface. The plugin's code lacks proper input validation and sanitization mechanisms before processing user-supplied data through the unserialize() function, which is a well-known vector for PHP Object Injection attacks. This occurs because the plugin fails to properly escape and sanitize data before incorporating it into HTTP responses, creating conditions where malicious payloads can be stored and subsequently executed. The vulnerability specifically targets the customizer options import functionality, which is exposed to authenticated users through the WordPress admin interface.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to perform PHP Object Injection attacks that can lead to complete system compromise. A subscriber-level user can leverage this flaw to inject malicious PHP objects that, when unserialized, execute arbitrary code on the web server with the privileges of the web application. Additionally, the lack of proper sanitization creates opportunities for Stored Cross-Site Scripting attacks, where malicious scripts can be persisted in the application's database and executed whenever affected pages are loaded by other users. This dual nature of the vulnerability makes it particularly dangerous as it can be exploited for both remote code execution and client-side attacks.
From a cybersecurity perspective, this vulnerability aligns with multiple CWE categories including CWE-502 for Unserialization of Untrusted Data and CWE-79 for Cross-Site Scripting. The attack pattern follows the MITRE ATT&CK framework's T1059.007 technique for command and scripting interpreter, specifically targeting PHP-based execution environments. The vulnerability represents a classic example of insecure deserialization where user-provided data is directly passed to unserialize() without proper validation or sanitization. Organizations running affected WordPress installations face significant risk of unauthorized access, data breaches, and potential full system compromise, especially when the plugin is used in environments with multiple user roles or when subscribers have access to administrative features.
The recommended mitigations for this vulnerability include immediate patching of the Insight Core plugin to version 1.1 or later, which should contain proper authorization checks and input validation. Administrators should also implement network-level restrictions to limit access to plugin endpoints and consider disabling unnecessary plugin features. Additionally, regular security audits should verify that no malicious code has been injected into the system, and monitoring should be enhanced to detect unusual patterns in plugin usage or unauthorized modifications to core WordPress components. Organizations should also consider implementing Web Application Firewalls and content security policies to add additional layers of protection against exploitation attempts.