CVE-2002-1961 in Surfingate
Summary
by MITRE
Finjan Software SurfinGate 6.0 and 6.0 1 allows remote attackers to bypass URL access restrictions via a URL whose hostname portion uses a fully qualified domain name (FQDN) that ends in a "." (dot).
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Analysis
by VulDB Data Team • 04/23/2025
The vulnerability identified as CVE-2002-1961 affects Finjan Software SurfinGate 6.0 and 6.0 1, representing a significant security flaw in web proxy and content filtering systems. This issue stems from improper handling of fully qualified domain names within URL parsing mechanisms, creating a bypass opportunity for remote attackers seeking to circumvent access controls. The vulnerability specifically targets the hostname portion of URLs where the domain name ends with a trailing dot character, which is a valid but often overlooked format in DNS specifications.
The technical root cause of this vulnerability lies in the flawed URL parsing logic within the SurfinGate application. When processing URLs with hostnames ending in a period, the system fails to properly normalize or validate the domain name format, allowing attackers to craft malicious URLs that appear to belong to different domains. This parsing error creates a discrepancy between how the system interprets the URL and how it should enforce access controls. The trailing dot in FQDNs is a legitimate DNS construct that indicates the domain is fully qualified, but the SurfinGate implementation does not account for this properly during access restriction enforcement.
From an operational standpoint, this vulnerability presents a serious risk to organizations relying on SurfinGate for web content filtering and access control. Attackers could exploit this flaw to bypass restrictions that would normally prevent access to certain websites or content categories, potentially allowing unauthorized access to restricted resources or enabling malicious activities such as accessing blocked malware repositories or prohibited social media platforms. The remote nature of the attack means that threat actors do not require local system access or credentials to exploit this vulnerability, making it particularly dangerous for enterprise environments.
The security implications extend beyond simple access bypass, as this vulnerability could enable more sophisticated attacks including man-in-the-middle scenarios, data exfiltration attempts, or redirection to malicious sites. Organizations using this software may experience unauthorized access to sensitive information, compromised network security posture, and potential violations of compliance requirements. The vulnerability demonstrates a classic input validation flaw that can be categorized under CWE-20, which addresses "Improper Input Validation" in software systems. This weakness allows attackers to manipulate system behavior through malformed input data, in this case specifically crafted URLs with unusual domain name formats.
Mitigation strategies should focus on immediate software updates from Finjan Software, as the vendor would have likely released patches addressing this specific URL parsing issue. Organizations should also implement additional network monitoring to detect unusual URL patterns or access attempts that might indicate exploitation attempts. Network administrators should consider implementing more robust URL filtering mechanisms that normalize domain name formats before processing, and establish regular security assessments to identify similar parsing vulnerabilities in other network security tools. The ATT&CK framework would categorize this vulnerability under T1071.004 for Application Layer Protocol: DNS, as it involves manipulation of DNS-related URL components to bypass security controls, potentially leading to T1566 for Phishing through the ability to redirect users to malicious sites.