CVE-2005-0238 in Mozilla
Summary
by MITRE
The International Domain Name (IDN) support in Epiphany allows remote attackers to spoof domain names using punycode encoded domain names that are decoded in URLs and SSL certificates in a way that uses homograph characters from other character sets, which facilitates phishing attacks.
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Analysis
by VulDB Data Team • 06/20/2024
The vulnerability described in CVE-2005-0238 represents a significant security flaw in the International Domain Name (IDN) implementation within the Epiphany web browser. This issue specifically targets the browser's handling of punycode encoded domain names and demonstrates how seemingly legitimate technical features can be exploited to create deceptive user experiences. The vulnerability operates by allowing attackers to register domain names that appear identical to legitimate sites but are actually composed of homograph characters from different character sets, creating a deceptive environment where users cannot distinguish between authentic and malicious domains through visual inspection alone. This particular weakness in Epiphany's IDN support creates a pathway for sophisticated phishing attacks that exploit the browser's decoding behavior in URLs and SSL certificates.
The technical flaw stems from how Epiphany processes IDN domain names during URL display and SSL certificate verification. When a user encounters a punycode encoded domain name, the browser decodes it for display purposes but fails to properly distinguish between the encoded representation and the actual character set used in the domain. This creates a situation where attackers can register domains using characters from different scripts that visually resemble characters from the latin alphabet, making it extremely difficult for users to identify malicious sites. The vulnerability specifically affects the way the browser handles character encoding and decoding, particularly in scenarios where the same visual appearance can be achieved through different character sets, a technique commonly known as homograph attack. This flaw is particularly dangerous because it operates at the intersection of international character support and security verification mechanisms, creating confusion between the visual representation of a domain name and its actual encoded form.
The operational impact of this vulnerability extends far beyond simple phishing attempts, as it fundamentally undermines user trust in the browser's ability to accurately display domain information. Users who rely on visual inspection to verify website authenticity become vulnerable to sophisticated attacks where malicious actors can register domains that appear identical to legitimate sites but contain different character sets. This creates a dangerous environment where users may unknowingly navigate to malicious websites while believing they are visiting trusted domains, potentially leading to credential theft, financial fraud, or other malicious activities. The vulnerability is particularly concerning in environments where users may not be familiar with international character sets or may not notice subtle differences in character appearance. The security implications are exacerbated by the fact that SSL certificates, which are supposed to provide authentication and encryption guarantees, can be effectively bypassed through this visual deception mechanism.
Mitigation strategies for this vulnerability should focus on implementing proper character set validation and display mechanisms that prevent visual homograph attacks from succeeding. Security measures must include enhanced URL display protocols that either prevent the use of non-latin characters in domain names or provide clear visual indicators when such characters are present. Browser vendors should implement proper IDN handling that maintains consistency between encoded and decoded representations while ensuring that users can clearly distinguish between different character sets. Additionally, certificate validation processes should be strengthened to detect and flag potential homograph attacks, particularly in scenarios where the visual representation of a domain name does not match the encoded form. This vulnerability highlights the importance of considering internationalization security implications in browser design and demonstrates the need for comprehensive security testing that includes character set handling and visual verification mechanisms. The issue also underscores the necessity of implementing security controls that align with established security frameworks and best practices for preventing character-based attacks. Organizations should consider implementing additional user education about the risks of IDN homograph attacks and ensure that their security infrastructure can detect and respond to such sophisticated phishing techniques.