CVE-2007-0779 in Firefox
Summary
by MITRE
GUI overlay vulnerability in Mozilla Firefox 1.5.x before 1.5.0.10 and 2.x before 2.0.0.2, and SeaMonkey before 1.0.8 allows remote attackers to spoof certain user interface elements, such as the host name or security indicators, via the CSS3 hotspot property with a large, transparent, custom cursor.
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Analysis
by VulDB Data Team • 07/13/2021
The vulnerability described in CVE-2007-0779 represents a significant graphical user interface overlay flaw that affected major web browsers including Mozilla Firefox versions 1.5.x prior to 1.5.0.10 and 2.x prior to 2.0.0.2, as well as SeaMonkey versions before 1.0.8. This security weakness stems from improper handling of CSS3 hotspot properties combined with custom cursor implementations, creating an avenue for malicious actors to manipulate the browser's visual presentation layer. The flaw specifically exploits the browser's rendering engine's inability to properly validate and isolate user interface elements when transparent cursors are applied through CSS3 specifications, allowing attackers to overlay deceptive interface components over legitimate browser elements.
The technical execution of this vulnerability relies on the manipulation of CSS3 hotspot properties to create large, transparent custom cursors that can be positioned to obscure or replace critical user interface elements. When browsers process these specially crafted cursor definitions, they fail to properly distinguish between legitimate interface components and maliciously overlaid elements, particularly affecting security indicators and host name displays. This occurs because the browser's rendering engine does not adequately validate the positioning and layering of cursor elements against other UI components, creating a visual overlay attack vector. The vulnerability is particularly dangerous because it operates at the presentation layer rather than the application or network layer, making it difficult to detect through traditional security monitoring approaches.
The operational impact of this vulnerability extends beyond simple visual deception to potentially enable sophisticated phishing attacks and credential theft operations. Attackers can exploit this flaw to make users believe they are visiting a legitimate secure website when they are actually interacting with a malicious page, as the security indicators that normally warn users about certificate issues or untrusted connections become obscured or replaced. This type of attack directly violates the principle of least privilege and user trust in browser security mechanisms, as users cannot rely on the visual cues that browsers provide to verify their connection security status. The vulnerability essentially undermines the browser's ability to provide meaningful security warnings, creating an environment where users may unknowingly submit sensitive information to malicious actors.
This vulnerability maps directly to CWE-690, which addresses unsafe use of library APIs, specifically in the context of GUI rendering and user interface element handling. The attack pattern aligns with techniques described in the MITRE ATT&CK framework under T1059 for execution through web-based attacks, and T1566 for social engineering through spoofed interfaces. The flaw demonstrates how seemingly benign CSS3 features can be weaponized when combined with browser rendering engine limitations. Organizations should implement immediate patch management procedures to address this vulnerability, as the affected browser versions were widely deployed in enterprise environments. Additionally, browser security hardening measures including strict content security policy enforcement and regular security audits of web content should be implemented to prevent exploitation of similar rendering engine vulnerabilities. The incident highlights the importance of comprehensive testing of CSS and rendering features in security-sensitive applications, particularly when dealing with user interface overlay operations that could affect security-critical elements.