CVE-2022-3989 in Motors Plugin
Summary
by MITRE • 12/12/2022
The Motors WordPress plugin before 1.4.4 does not properly validate uploaded files for dangerous file types (such as .php) in an AJAX action, allowing an attacker to sign up on a victim's WordPress instance, upload a malicious PHP file and attempt to launch a brute-force attack to discover the uploaded payload.
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Analysis
by VulDB Data Team • 01/07/2023
The CVE-2022-3989 vulnerability affects the Motors WordPress plugin version 1.4.3 and earlier, presenting a critical security flaw that stems from inadequate file validation mechanisms within the plugin's AJAX upload functionality. This vulnerability specifically targets the plugin's failure to properly sanitize and validate file types during the upload process, creating an exploitable condition that allows remote attackers to bypass security controls and upload malicious files to WordPress installations. The flaw exists in the plugin's handling of user-uploaded content through AJAX requests, which are commonly used for asynchronous operations without full page reloads, making the attack vector particularly stealthy and difficult to detect through standard monitoring mechanisms.
The technical implementation of this vulnerability enables attackers to exploit the plugin's weak validation logic by uploading PHP files with potentially malicious code, as the system does not adequately verify file extensions, MIME types, or file content against known dangerous patterns. This improper validation creates a path for privilege escalation and persistent access to compromised WordPress instances, as the uploaded PHP files can execute arbitrary code on the server when accessed through the web application. The vulnerability's impact is exacerbated by the fact that attackers can leverage the plugin's legitimate user registration functionality to gain access to the WordPress instance before executing their upload attack, making the exploitation process more straightforward and less likely to trigger security alerts.
The operational consequences of CVE-2022-3989 extend beyond simple file upload capabilities, as it enables attackers to establish persistent backdoors, conduct brute-force attacks against the uploaded payloads, and potentially escalate privileges within the compromised environment. This vulnerability aligns with CWE-434, which addresses the improper restriction of uploads of executable files, and represents a significant weakness in the plugin's input validation and file handling processes. The attack scenario typically involves an attacker registering an account on a target WordPress instance, leveraging the Motors plugin's upload functionality to place malicious PHP files, and then using these files to launch further attacks including credential brute-forcing or establishing reverse shells. This vulnerability directly impacts the principle of least privilege and can lead to complete compromise of the affected WordPress installation.
Mitigation strategies for CVE-2022-3989 require immediate patching of the Motors plugin to version 1.4.4 or later, which addresses the file validation issues through enhanced input sanitization and proper MIME type checking. Organizations should implement additional defensive measures including restricting file upload capabilities to authenticated users only, implementing strict file extension filtering, and deploying web application firewalls to monitor and block suspicious upload patterns. The vulnerability demonstrates the importance of proper input validation and the principle of defense in depth, as outlined in the MITRE ATT&CK framework where this weakness maps to techniques involving file and directory permissions modifications and execution of malicious code. Security teams should also conduct comprehensive audits of all installed WordPress plugins to identify similar validation flaws, implement automated scanning for vulnerable components, and establish monitoring protocols to detect unauthorized file uploads or suspicious user activities that may indicate exploitation attempts.