CVE-2024-4157 in Contact Form Plugin
Summary
by MITRE • 05/22/2024
The Contact Form Plugin by Fluent Forms for Quiz, Survey, and Drag & Drop WP Form Builder plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 5.1.15 via deserialization of untrusted input in the extractDynamicValues function. This makes it possible for authenticated attackers, with contributor-level access and above, to inject a PHP Object. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code. Successful exploitation requires the attacker to have "View Form" and "Manage Form" permissions, which must be explicitly set by an administrator. However, this requirement can be bypassed when this vulnerability is chained with CVE-2024-2771.
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Analysis
by VulDB Data Team • 07/27/2024
The vulnerability identified as CVE-2024-4157 affects the Contact Form Plugin by Fluent Forms, a popular WordPress plugin used for creating quizzes, surveys, and drag-and-drop form builders. This plugin has been widely adopted across WordPress installations, making the vulnerability particularly concerning from a security perspective. The flaw exists within the extractDynamicValues function where untrusted input undergoes deserialization without proper sanitization, creating a pathway for malicious object injection attacks. The vulnerability impacts all versions up to and including 5.1.15, representing a significant security gap that has persisted across multiple releases of this popular plugin.
The technical exploitation of this vulnerability relies on PHP Object Injection principles, which fall under CWE-502 in the Common Weakness Enumeration catalog. The vulnerability occurs when the plugin deserializes user-supplied data without adequate validation or sanitization, allowing attackers to inject malicious PHP objects into the application's memory space. This deserialization process can be manipulated by authenticated users with contributor-level access or higher, as they possess the necessary permissions to interact with form management functionality. The attack vector specifically targets the extractDynamicValues function, which processes dynamic form data and fails to properly validate or escape the input before deserializing it into PHP objects.
From an operational standpoint, the impact of this vulnerability extends beyond simple data manipulation, as it creates potential for remote code execution when combined with existing POP (PHP Object Pollution) chains present in other plugins or themes. The attacker's ability to inject PHP objects opens doors to various malicious activities including arbitrary file deletion, sensitive data retrieval, and code execution on the target system. The requirement for "View Form" and "Manage Form" permissions, while seemingly restrictive, can be bypassed through chaining with CVE-2024-2771, which demonstrates how vulnerabilities often compound when multiple weaknesses exist within the same system. This chaining capability significantly increases the attack surface and makes the exploitation more accessible to threat actors with limited initial privileges.
The security implications of this vulnerability align with ATT&CK framework techniques related to privilege escalation and code execution. The vulnerability represents a path for attackers to escalate their privileges from contributor level to full system compromise, particularly when combined with other vulnerabilities in the WordPress ecosystem. Mitigation strategies should focus on immediate plugin updates to versions that address this deserialization vulnerability, along with implementing proper input validation and sanitization measures. Administrators should also consider implementing additional security controls such as role-based access restrictions, regular security audits, and monitoring for suspicious form-related activities. The vulnerability highlights the critical importance of proper object serialization and deserialization practices in web applications, particularly those handling user-generated content, and underscores the necessity of comprehensive security testing for all components of WordPress plugin ecosystems.