CVE-2025-49401: Quiz And Survey Master RCE Vulnerability

CVE-2025-49401 Overview

A critical insecure deserialization vulnerability has been discovered in ExpressTech Systems Quiz And Survey Master, a popular WordPress plugin used for creating quizzes and surveys. The vulnerability allows unauthenticated attackers to inject malicious PHP objects through untrusted data deserialization, potentially leading to remote code execution, data theft, or complete site compromise.

Critical Impact

This PHP Object Injection vulnerability enables unauthenticated attackers to execute arbitrary code on vulnerable WordPress installations, potentially leading to complete site takeover, data exfiltration, and lateral movement within hosting environments.

Affected Products

• Quiz And Survey Master WordPress plugin versions through 10.2.5
• WordPress installations running vulnerable Quiz And Survey Master versions
• Websites utilizing quiz or survey functionality from ExpressTech Systems

Discovery Timeline

• September 5, 2025 - CVE-2025-49401 published to NVD
• September 5, 2025 - Last updated in NVD database

Technical Details for CVE-2025-49401

Vulnerability Analysis

This vulnerability falls under CWE-502 (Deserialization of Untrusted Data), a dangerous class of security flaws that occurs when an application deserializes data from untrusted sources without proper validation. In the context of Quiz And Survey Master, the plugin fails to adequately sanitize serialized data before processing it through PHP's deserialization mechanisms.

The impact of this vulnerability is severe. An attacker can craft malicious serialized payloads that, when deserialized by the vulnerable plugin, instantiate arbitrary PHP objects with attacker-controlled properties. If exploitable gadget chains exist within the WordPress installation or its plugins, this can escalate to remote code execution, file system manipulation, or database compromise.

Root Cause

The root cause of this vulnerability is improper handling of user-supplied serialized data within the Quiz And Survey Master plugin. The application accepts and deserializes data without implementing sufficient validation or using safe deserialization practices. PHP's native unserialize() function, when called on untrusted input, can instantiate arbitrary objects and trigger magic methods such as __wakeup(), __destruct(), or __toString(), which may execute malicious code if exploitable classes exist in the application scope.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can submit specially crafted serialized PHP objects through HTTP requests to vulnerable endpoints exposed by the Quiz And Survey Master plugin. The malicious payload is then processed by the server, triggering the deserialization vulnerability.

The exploitation flow typically involves:

1. Identifying an endpoint that accepts and deserializes user input
2. Discovering usable gadget chains within WordPress core, the vulnerable plugin, or other installed plugins
3. Crafting a serialized payload that chains object instantiations to achieve code execution
4. Submitting the payload to the vulnerable endpoint via HTTP request
5. The server deserializes the malicious data, triggering the gadget chain and executing attacker-controlled code

Common exploitation techniques leverage Property Oriented Programming (POP) chains, where the attacker abuses existing class methods that are automatically invoked during deserialization. For detailed technical analysis, refer to the Patchstack WordPress Vulnerability Advisory.

Detection Methods for CVE-2025-49401

Indicators of Compromise

• Unusual HTTP POST requests containing serialized PHP data (look for patterns like O: followed by class names and property structures)
• Web server logs showing requests to Quiz And Survey Master endpoints with abnormal payload sizes or encoded serialized content
• Unexpected file modifications in WordPress directories, particularly wp-content/plugins/ and wp-content/uploads/
• New or modified PHP files with obfuscated code or webshell characteristics
• Anomalous database entries or modified WordPress options containing serialized objects

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block serialized PHP object patterns in HTTP requests
• Monitor for suspicious process execution originating from the web server process (e.g., php-fpm, apache, nginx)
• Implement file integrity monitoring on WordPress installations to detect unauthorized file modifications
• Review access logs for requests to /wp-admin/admin-ajax.php or plugin-specific endpoints with suspicious payloads
• Utilize SentinelOne's behavioral AI to detect post-exploitation activities such as reverse shells or lateral movement

Monitoring Recommendations

• Enable detailed logging for the Quiz And Survey Master plugin and review for deserialization-related errors
• Set up alerts for new PHP file creation in web-accessible directories
• Monitor outbound network connections from the web server for command-and-control communication
• Implement runtime application self-protection (RASP) to detect object injection attacks at the application layer

How to Mitigate CVE-2025-49401

Immediate Actions Required

• Update Quiz And Survey Master to a patched version as soon as one becomes available from ExpressTech Systems
• If immediate patching is not possible, consider temporarily deactivating the Quiz And Survey Master plugin until a fix is released
• Implement WAF rules to block requests containing serialized PHP object patterns
• Conduct a thorough review of your WordPress installation for signs of compromise
• Review and restrict file system permissions to prevent unauthorized file creation

Patch Information

Organizations should monitor the official Quiz And Survey Master plugin page and the Patchstack WordPress Vulnerability Advisory for patch availability. Update to a version higher than 10.2.5 once a security fix is released.

Workarounds

• Temporarily disable the Quiz And Survey Master plugin if it is not critical to site operations
• Implement strict input validation at the WAF or reverse proxy level to filter serialized data patterns
• Consider placing the WordPress admin panel and plugin endpoints behind additional authentication layers
• Use PHP configuration to disable dangerous functions such as exec, system, passthru, and shell_exec to limit post-exploitation impact
• Regularly backup WordPress installations to enable rapid recovery in case of compromise

# Example WAF rule pattern to block PHP serialized objects (ModSecurity)
SecRule REQUEST_BODY "@rx O:\d+:\"[a-zA-Z_][a-zA-Z0-9_]*\":\d+:\{" \
    "id:100001,phase:2,deny,status:403,msg:'Potential PHP Object Injection Attack'"