CVE-2019-25426
📋 TL;DR
Comodo Dome Firewall 2.7.0 contains a reflected cross-site scripting vulnerability in its dnsmasq endpoint. Attackers can inject malicious JavaScript via crafted POST requests to the TRANSPARENT_SOURCE_BYPASS or TRANSPARENT_DESTINATION_BYPASS parameters, potentially compromising users' browsers. Organizations using Comodo Dome Firewall 2.7.0 are affected.
💻 Affected Systems
- Comodo Dome Firewall
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator credentials, hijack sessions, redirect users to malicious sites, or perform actions on behalf of authenticated users, potentially leading to full firewall compromise.
Likely Case
Attackers could steal session cookies or credentials from authenticated administrators, leading to unauthorized access to the firewall management interface.
If Mitigated
With proper input validation and output encoding, the malicious scripts would be rendered harmless as text rather than executable code.
🎯 Exploit Status
Exploit code is publicly available on Exploit-DB (ID 46408). The attack requires the victim to click a malicious link but doesn't require authentication to the firewall.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.8.0 or later
Vendor Advisory: https://cdome.comodo.com/firewall/
Restart Required: Yes
Instructions:
1. Log into the Comodo Dome Firewall management interface. 2. Navigate to System > Updates. 3. Check for available updates. 4. Apply the update to version 2.8.0 or later. 5. Restart the firewall service as prompted.
🔧 Temporary Workarounds
Input Validation Filter
allImplement input validation to sanitize the TRANSPARENT_SOURCE_BYPASS and TRANSPARENT_DESTINATION_BYPASS parameters before processing.
Web Application Firewall Rules
allDeploy WAF rules to block requests containing script tags or JavaScript patterns in the vulnerable parameters.
🧯 If You Can't Patch
- Implement strict Content Security Policy (CSP) headers to prevent script execution from untrusted sources.
- Restrict access to the firewall management interface to trusted IP addresses only using network ACLs.
🔍 How to Verify
Check if Vulnerable:
Test by sending a POST request to the dnsmasq endpoint with a script payload in TRANSPARENT_SOURCE_BYPASS parameter and checking if it executes in the response.Check Version:
ssh admin@firewall-ip 'show version' or check via web interface at System > AboutVerify Fix Applied:
After patching, repeat the vulnerability test to confirm script payloads are properly sanitized and do not execute.📡 Detection & Monitoring
Log Indicators:
- POST requests to /dnsmasq endpoint with script tags or JavaScript patterns in parameters
- Unusual parameter values containing <script>, javascript:, or eval() patterns
Network Indicators:
- HTTP requests with suspicious payloads in TRANSPARENT_SOURCE_BYPASS or TRANSPARENT_DESTINATION_BYPASS parameters
SIEM Query:
source="firewall_logs" AND uri_path="/dnsmasq" AND (param_name="TRANSPARENT_SOURCE_BYPASS" OR param_name="TRANSPARENT_DESTINATION_BYPASS") AND (param_value CONTAINS "<script>" OR param_value CONTAINS "javascript:")