CVE-2007-0802 in Web Browser
Summary
by MITRE
Mozilla Firefox 2.0.0.1 allows remote attackers to bypass the Phishing Protection mechanism by adding certain characters to the end of the domain name, as demonstrated by the "." and "/" characters, which is not caught by the Phishing List blacklist filter.
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Analysis
by VulDB Data Team • 07/13/2021
The vulnerability described in CVE-2007-0802 represents a significant weakness in Mozilla Firefox 2.0.0.1's phishing protection system that directly undermines user security through domain name manipulation techniques. This flaw operates by exploiting a gap in how the browser's anti-phishing mechanism validates domain names, specifically targeting the filtering logic that should prevent users from being tricked into visiting malicious websites that mimic legitimate ones through subtle domain name variations. The vulnerability allows attackers to bypass security measures by appending specific characters such as periods and forward slashes to the end of domain names, effectively evading detection by the phishing list blacklist filter that is designed to block known malicious domains.
The technical implementation of this vulnerability stems from insufficient input validation within Firefox's domain parsing and comparison algorithms. When the browser processes domain names for phishing protection, it fails to properly normalize or canonicalize domain names before comparison against the blacklist. This allows attackers to craft domain names that appear legitimate to users while remaining undetected by the security filter due to the way the system handles trailing characters. The specific characters ". " and "/" mentioned in the vulnerability description are particularly effective because they can alter the domain parsing behavior in ways that bypass the security checks designed to prevent such attacks. This type of vulnerability falls under the CWE-170 category of improper handling of string termination, where the system fails to properly process or validate string inputs that contain special characters or unusual formatting.
The operational impact of this vulnerability is substantial as it effectively neutralizes one of the primary defenses against phishing attacks in a widely used web browser. Users who encounter phishing attempts that exploit this vulnerability may be misled into believing they are visiting legitimate websites when they are actually connecting to malicious domains. This creates a false sense of security that can lead to credential theft, financial fraud, and other malicious activities. The vulnerability demonstrates a critical flaw in the browser's security architecture where the protection mechanism itself can be circumvented through simple character manipulation, potentially affecting millions of users who rely on Firefox's built-in phishing protection. The attack vector is particularly dangerous because it requires no sophisticated exploitation techniques and can be executed through simple URL manipulation.
Security professionals should consider this vulnerability in the context of the broader ATT&CK framework, specifically under the T1566 technique of Phishing, where attackers exploit web browser security weaknesses to deliver malicious content. The mitigation strategies for this vulnerability should include immediate patching of affected Firefox versions, implementation of additional validation layers in web application security, and enhanced monitoring of domain name patterns that might indicate attempted exploitation. Organizations should also consider implementing additional security measures such as extended validation certificates, enhanced DNS filtering, and user education programs to reduce the risk of successful phishing attacks. The vulnerability highlights the importance of comprehensive input validation and the need for security mechanisms to properly handle edge cases in domain name parsing and comparison operations. This flaw serves as a reminder that even well-established security features can contain implementation gaps that attackers can exploit through creative manipulation of input parameters, emphasizing the critical need for robust testing and validation of security controls against various attack vectors.