CVE-2024-13777: ZoomSounds PHP Object Injection Flaw

CVE-2024-13777 Overview

The ZoomSounds - WordPress Wave Audio Player with Playlist plugin for WordPress contains a PHP Object Injection vulnerability in all versions up to, and including, 6.91. The vulnerability exists due to deserialization of untrusted input from the margs parameter. This allows unauthenticated attackers to inject a PHP Object into the application. While no known POP (Property Oriented Programming) chain is present in the vulnerable software itself, if a POP chain exists via another plugin or theme installed on the target system, attackers may be able to delete arbitrary files, retrieve sensitive data, or execute arbitrary code.

Critical Impact
Unauthenticated attackers can exploit insecure deserialization to inject malicious PHP objects, potentially leading to remote code execution, data theft, or file deletion when combined with an existing POP chain from another installed plugin or theme.

Affected Products

digitalzoomstudio zoomsounds (all versions up to and including 6.91)
WordPress sites running the ZoomSounds plugin
WordPress environments with additional plugins or themes containing POP chains

Discovery Timeline

2025-03-05 - CVE CVE-2024-13777 published to NVD
2025-05-26 - Last updated in NVD database

Technical Details for CVE-2024-13777

Vulnerability Analysis

This vulnerability is classified as Insecure Deserialization (CWE-502). The ZoomSounds plugin accepts serialized PHP data through the margs parameter without proper validation or sanitization. When this untrusted input is deserialized, it allows an attacker to construct arbitrary PHP objects with attacker-controlled properties.

The exploitation potential of PHP Object Injection vulnerabilities depends heavily on the presence of "magic methods" (such as __wakeup(), __destruct(), or __toString()) in classes available within the application's scope. These methods are automatically invoked during deserialization and can be chained together to form a POP chain that performs malicious actions.

In this case, while the ZoomSounds plugin itself does not contain a known exploitable POP chain, the WordPress ecosystem's extensive use of plugins and themes significantly increases the likelihood that a vulnerable chain exists on any given installation.

Root Cause

The root cause of this vulnerability is the use of PHP's unserialize() function on user-controlled input without proper input validation or sanitization. The margs parameter accepts serialized data that is directly passed to the deserialization function, trusting that the input is legitimate. This violates the principle of never deserializing untrusted data, as serialized PHP objects can contain arbitrary class instances with attacker-controlled property values.

Attack Vector

The attack is network-based and can be executed by unauthenticated users. An attacker crafts a malicious serialized PHP object payload and submits it through the margs parameter. The payload is designed to instantiate specific classes that, when their magic methods are triggered during deserialization, execute a chain of method calls leading to the attacker's desired outcome.

The attack flow typically involves:

Identifying the vulnerable margs parameter endpoint in the ZoomSounds plugin
Enumerating available classes on the target WordPress installation that contain exploitable magic methods
Constructing a serialized payload that chains these classes together (POP chain)
Submitting the malicious payload to trigger deserialization and code execution

For technical details on the vulnerability mechanism, refer to the Wordfence Vulnerability Report.

Detection Methods for CVE-2024-13777

Indicators of Compromise

Unusual HTTP POST requests containing serialized PHP data (strings starting with O:, a:, s:) in the margs parameter
Unexpected file deletions or modifications on WordPress installations
Web server logs showing requests to ZoomSounds plugin endpoints with encoded or obfuscated payloads
Evidence of reconnaissance activity targeting WordPress plugin versions

Detection Strategies

Monitor web application firewall (WAF) logs for serialized PHP object patterns in request parameters
Implement signature-based detection rules for PHP serialization patterns in HTTP traffic (e.g., regex patterns matching O:\d+:"[^"]+":)
Deploy runtime application self-protection (RASP) solutions to detect deserialization attempts
Conduct regular vulnerability scans of WordPress installations to identify outdated plugin versions

Monitoring Recommendations

Enable detailed logging for WordPress and web server access logs to capture full request parameters
Set up alerts for anomalous activity on ZoomSounds plugin endpoints
Monitor file integrity on critical WordPress directories to detect unauthorized modifications
Implement network-level monitoring for outbound connections from the web server that may indicate successful exploitation

How to Mitigate CVE-2024-13777

Immediate Actions Required

Update the ZoomSounds plugin to the latest patched version immediately
Audit WordPress installations to identify all sites running vulnerable versions of ZoomSounds
Review installed plugins and themes for known POP chains that could be exploited in conjunction with this vulnerability
Implement web application firewall rules to block serialized PHP objects in request parameters

Patch Information

Organizations should update the ZoomSounds - WordPress Wave Audio Player with Playlist plugin to a version newer than 6.91 that addresses this vulnerability. Check the Codecanyon Plugin Page for the latest version and update instructions.

Workarounds

If immediate patching is not possible, consider temporarily disabling the ZoomSounds plugin until a patch can be applied
Implement WAF rules to block requests containing serialized PHP data in the margs parameter
Restrict access to WordPress admin and plugin endpoints through IP whitelisting where feasible
Remove unnecessary plugins and themes to reduce the attack surface for POP chain exploitation

bash

# Configuration example - WAF rule to block PHP serialization patterns
# ModSecurity rule example
SecRule ARGS "@rx O:\d+:\"[^\"]+\":\d+:{" \
    "id:100001,\
    phase:2,\
    deny,\
    status:403,\
    log,\
    msg:'PHP Object Injection attempt detected',\
    tag:'CVE-2024-13777'"