CVE-2023-4243 in FULL Customer Plugin
Summary
by MITRE • 08/09/2023
The FULL - Customer plugin for WordPress is vulnerable to Arbitrary File Upload via the /install-plugin REST route in versions up to, and including, 2.2.3 due to improper authorization. This allows authenticated attackers with subscriber-level permissions and above to execute code by installing plugins from arbitrary remote locations including non-repository sources onto the site, granted they are packaged as a valid WordPress plugin.
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Analysis
by VulDB Data Team • 09/01/2023
The CVE-2023-4243 vulnerability affects the FULL - Customer plugin for WordPress, representing a critical security flaw that enables unauthorized code execution through improper authorization mechanisms. This vulnerability exists within the /install-plugin REST route of the plugin, specifically impacting versions up to and including 2.2.3. The flaw allows authenticated attackers who possess subscriber-level permissions or higher to exploit the system by installing malicious plugins from arbitrary remote sources, effectively bypassing normal security controls that should prevent such installations.
The technical implementation of this vulnerability stems from inadequate access control validation within the plugin's REST API endpoint. When an attacker with subscriber privileges attempts to install a plugin through the /install-plugin route, the system fails to properly verify whether the user has appropriate authorization to perform this action. This authorization bypass occurs because the plugin does not adequately validate the user's permissions or the source of the plugin being installed, creating a pathway for malicious code deployment. The vulnerability is particularly dangerous because it leverages legitimate WordPress plugin installation mechanisms while circumventing normal security boundaries.
From an operational perspective, this vulnerability creates significant risks for WordPress sites using the affected plugin. Attackers can leverage this flaw to install malicious plugins that may include backdoors, malware, or other harmful code that can persist on the system. The impact extends beyond simple code execution as it allows attackers to potentially gain full control over the WordPress installation, including access to user data, site content, and potentially the underlying server infrastructure. The vulnerability is especially concerning because it requires only subscriber-level permissions, which are often granted to users who are not considered high-risk, making detection more difficult and increasing the attack surface.
The exploitation of this vulnerability aligns with several ATT&CK framework techniques including T1059.001 for command and script interpreter and T1505.003 for server-side injection, as attackers can execute code through the plugin installation process. Additionally, this vulnerability maps to CWE-285, which addresses improper authorization in software systems, and CWE-434, which covers insecure file upload vulnerabilities. Organizations using the FULL - Customer plugin should immediately implement mitigations including updating to the patched version, implementing additional access controls, and monitoring for unauthorized plugin installations. The vulnerability demonstrates the importance of proper authorization checks in REST API implementations and the need for robust validation of user permissions before allowing sensitive operations to proceed.
Organizations should also consider implementing network-level protections such as web application firewalls to detect and block suspicious plugin installation requests, while maintaining comprehensive monitoring of plugin installation activities. Regular security audits of installed plugins and their versions should be conducted to identify and remediate similar vulnerabilities. The incident highlights the critical importance of validating all user actions within REST API endpoints and implementing defense-in-depth strategies to protect against privilege escalation attacks. Given that the vulnerability affects a widely used plugin, administrators should prioritize patching and consider conducting security assessments of their WordPress installations to identify potential exploitation attempts.