CVE-2005-4809 in Firefox
Summary
by MITRE
Mozilla Firefox 1.0.1 and possibly other versions, including Mozilla and Thunderbird, allows remote attackers to spoof the URL in the Status Bar via an A HREF tag that contains a TABLE tag that contains another A tag.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 01/10/2025
This vulnerability represents a sophisticated user interface spoofing attack that exploits the rendering behavior of web browsers when processing nested html elements. The flaw specifically affects mozilla firefox version 1.0.1 and potentially other mozilla-based browsers including thunderbird email client. The vulnerability occurs when a malicious web page constructs an a href tag that contains a table tag which itself contains another a tag, creating a complex nested structure that browsers interpret incorrectly during status bar URL display. This allows attackers to manipulate the url shown in the browser's status bar, potentially deceiving users into believing they are visiting a legitimate website when in fact they are navigating to a malicious location. The technical implementation involves the browser's parsing logic failing to properly handle nested anchor tags within table structures, causing the status bar to display a spoofed URL rather than the actual page location.
The operational impact of this vulnerability extends beyond simple deception as it undermines fundamental security mechanisms that users rely upon for navigation safety. When users see a misleading URL in the status bar, they may inadvertently trust the website and proceed to enter sensitive information or download malicious content. This vulnerability directly violates the principle of least privilege and user trust in browser security interfaces, as it allows attackers to manipulate one of the most visible indicators of browser security. The attack vector is particularly dangerous because it leverages the browser's legitimate html parsing capabilities to create a security bypass rather than exploiting a direct code execution flaw.
From a cybersecurity perspective, this vulnerability aligns with multiple attack patterns documented in the attack tree framework, specifically representing a form of phishing deception that targets user interface trust mechanisms. The flaw demonstrates how seemingly benign html parsing behavior can be exploited to create security vulnerabilities, making it a classic example of a bypass vulnerability that operates through indirect means. This type of vulnerability would be classified under common weakness enumeration category 611 which covers improper access control, though it specifically targets the status bar display rather than access permissions. The attack essentially creates a false sense of security by manipulating the visual feedback that users expect to see when navigating the web.
Mitigation strategies for this vulnerability require both client-side and server-side approaches. Browser vendors should implement proper html parsing validation to prevent nested anchor tags from creating misleading status bar displays, while also ensuring that status bar url information accurately reflects the actual page location rather than the parsed html structure. Users should be educated about the importance of verifying urls in the address bar rather than relying solely on status bar information, as this vulnerability specifically targets the status bar's trustworthiness. Additionally, implementing content security policies and proper html sanitization on web servers can help prevent malicious html structures from being delivered to browsers. The vulnerability also highlights the need for comprehensive browser security testing that includes edge cases in html parsing behavior, particularly around nested elements that could create unexpected rendering outcomes.
This vulnerability type represents a significant concern for browser security design and demonstrates how user interface elements that are meant to enhance usability can inadvertently create security risks. The flaw underscores the importance of thorough security testing of browser rendering engines and the potential for seemingly innocuous html structures to be exploited for malicious purposes. It also illustrates the need for security professionals to consider not just direct code execution vulnerabilities, but also indirect attack vectors that manipulate user trust through interface manipulation. The attack pattern would be categorized under attack technique T1566 in the attack tree framework, representing social engineering through technical means, and represents a classic example of how browser security must account for the complex interactions between html parsing and user interface trust mechanisms.