CVE-2000-0116 in Firewall-1
Summary
by MITRE
Firewall-1 does not properly filter script tags, which allows remote attackers to bypass the "Strip Script Tags" restriction by including an extra < in front of the SCRIPT tag.
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Analysis
by VulDB Data Team • 12/27/2024
The vulnerability identified as CVE-2000-0116 affects Check Point Firewall-1, a widely deployed network security solution that provides firewall and intrusion prevention capabilities. This flaw represents a critical security weakness in the application layer filtering mechanisms that are designed to protect network infrastructure from malicious web-based attacks. The vulnerability specifically targets the content filtering functionality that is intended to prevent cross-site scripting (XSS) attacks by removing potentially dangerous script tags from incoming web requests. The issue manifests when the system fails to adequately sanitize input data, creating a bypass mechanism that undermines the security controls designed to protect network resources from unauthorized access and malicious code execution.
The technical flaw in Firewall-1 stems from an insufficient implementation of script tag filtering logic that relies on simple pattern matching rather than comprehensive input validation. When an attacker crafts a malicious payload containing script tags with additional characters such as an extra opening angle bracket before the SCRIPT tag, the system's filtering mechanism fails to recognize this obfuscated variant as malicious content. This improper filtering allows the malicious code to pass through the security controls undetected, potentially enabling attackers to inject harmful scripts that can compromise user sessions, steal sensitive data, or perform unauthorized actions on behalf of legitimate users. The vulnerability demonstrates a classic case of inadequate input sanitization where the security mechanism only accounts for standard patterns and fails to consider obfuscation techniques that attackers commonly employ to bypass filters.
The operational impact of this vulnerability extends beyond simple bypass of security controls to represent a significant threat to network integrity and user security. When successful, the attack allows remote threat actors to circumvent the very protections that Firewall-1 is designed to provide, potentially enabling full exploitation of web applications behind the firewall. This weakness can be leveraged to execute arbitrary code in users' browsers, steal session cookies, redirect traffic to malicious sites, or perform other malicious activities that undermine the security posture of organizations relying on this protection mechanism. The vulnerability particularly affects environments where Firewall-1 is used as a web application firewall or content filter, making it a critical concern for enterprises that depend on proper filtering of web content to protect their networks from external threats.
Organizations should implement immediate mitigations including updating to patched versions of Firewall-1 that address the insufficient script tag filtering, implementing additional input validation layers, and deploying comprehensive web application firewalls that provide more robust protection against XSS attacks. The vulnerability aligns with CWE-79 which describes cross-site scripting flaws, and represents a specific case of CWE-20 which deals with improper input validation. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control communications and credential access through web-based attacks, potentially enabling adversaries to establish persistent access to network resources. Security teams should also consider implementing additional monitoring and detection mechanisms to identify attempts to exploit this vulnerability, as well as conducting thorough security assessments to ensure that similar filtering bypasses do not exist in other security controls within their infrastructure.