CVE-2019-25424: Comodo Dome Firewall XSS Vulnerability

CVE-2019-25424 Overview

Comodo Dome Firewall 2.7.0 contains a reflected cross-site scripting (XSS) vulnerability that allows attackers to inject malicious scripts by submitting unsanitized input to the EXCEPTIONSITELIST parameter. Attackers can craft POST requests to the https_exceptions endpoint with script payloads to execute arbitrary JavaScript in users' browsers and steal session data.

Critical Impact

Successful exploitation enables attackers to execute arbitrary JavaScript in the context of authenticated users' browser sessions, potentially leading to session hijacking, credential theft, and unauthorized administrative actions on the firewall management interface.

Affected Products

• Comodo Dome Firewall 2.7.0

Discovery Timeline

• 2026-02-19 - CVE CVE-2019-25424 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2019-25424

Vulnerability Analysis

This reflected XSS vulnerability (CWE-79) exists in the Comodo Dome Firewall's web-based management interface. The https_exceptions endpoint fails to properly sanitize user-supplied input in the EXCEPTIONSITELIST parameter before reflecting it back in the HTTP response. This allows an attacker to inject and execute arbitrary JavaScript code within the security context of an authenticated administrator's browser session.

The vulnerability is exploitable over the network and requires user interaction—specifically, the victim must click a malicious link or submit a crafted form. When exploited, the injected script runs with the same privileges as the authenticated user, enabling actions such as stealing session cookies, performing administrative operations, or redirecting users to malicious sites.

Root Cause

The root cause of this vulnerability is improper input validation and output encoding in the https_exceptions endpoint. The application fails to sanitize the EXCEPTIONSITELIST parameter value before including it in the HTML response, allowing script tags and JavaScript event handlers to be injected and executed by the victim's browser.

Attack Vector

The attack vector is network-based, requiring an attacker to trick an authenticated administrator into clicking a malicious link or submitting a crafted POST request. The attacker constructs a request to the https_exceptions endpoint containing JavaScript payloads in the EXCEPTIONSITELIST parameter. When the firewall's web interface processes this request and reflects the unsanitized input, the malicious script executes in the victim's browser context.

The exploitation technique typically involves social engineering to deliver the malicious link via phishing emails, instant messages, or compromised websites. Since this targets a firewall management interface, successful exploitation could give attackers control over network security configurations.

Detection Methods for CVE-2019-25424

Indicators of Compromise

• Unexpected JavaScript content or script tags appearing in HTTP requests to the https_exceptions endpoint
• Anomalous POST requests containing encoded script payloads in the EXCEPTIONSITELIST parameter
• Session cookies being transmitted to external or unknown domains
• Unusual administrative actions performed on the firewall shortly after administrators access suspicious links

Detection Strategies

• Deploy web application firewall (WAF) rules to detect and block requests containing script tags or JavaScript event handlers in POST parameters
• Monitor HTTP access logs for requests to https_exceptions containing suspicious patterns such as <script>, javascript:, or encoded variants
• Implement Content Security Policy (CSP) headers to restrict script execution sources and mitigate XSS impact

Monitoring Recommendations

• Enable detailed logging on the Comodo Dome Firewall management interface and forward logs to a SIEM for analysis
• Set up alerts for multiple failed or suspicious requests to administrative endpoints
• Monitor for session anomalies such as rapid geographic changes or unusual access patterns following link clicks

How to Mitigate CVE-2019-25424

Immediate Actions Required

• Restrict access to the Comodo Dome Firewall management interface to trusted networks or IP addresses only
• Implement additional authentication controls such as multi-factor authentication for administrative access
• Educate administrators about phishing risks and the importance of not clicking suspicious links while authenticated to management interfaces
• Consider deploying a reverse proxy with XSS filtering capabilities in front of the management interface

Patch Information

Consult Comodo's official channels for updated firmware or software versions that address this vulnerability. Review the VulnCheck Comodo Dome Advisory for additional remediation guidance. Technical details about the exploit are available at Exploit-DB #46408.

Workarounds

• Implement network-level access controls to limit who can reach the firewall management interface
• Use browser security extensions that block or warn about XSS attacks
• Deploy Content Security Policy headers at the network perimeter if the firewall interface cannot be directly patched
• Consider using an isolated browser or virtual machine for accessing administrative interfaces

# Example: Restrict management interface access via iptables
# Allow only trusted admin network (adjust IP range as needed)
iptables -A INPUT -p tcp --dport 443 -s 192.168.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP