CVE-2008-1241 in Firefox
Summary
by MITRE
GUI overlay vulnerability in Mozilla Firefox before 2.0.0.13 and SeaMonkey before 1.1.9 allows remote attackers to spoof form elements and redirect user inputs via a borderless XUL pop-up window from a background tab.
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Analysis
by VulDB Data Team • 08/07/2019
The vulnerability described in CVE-2008-1241 represents a significant security flaw in the user interface rendering mechanisms of Mozilla Firefox and SeaMonkey browsers. This issue stems from improper handling of graphical user interface overlay elements, specifically affecting versions prior to Firefox 2.0.0.13 and SeaMonkey 1.1.9. The vulnerability exploits a fundamental weakness in how these browsers manage XUL (XML User Interface Language) pop-up windows that can be displayed without traditional window borders, creating an environment where malicious actors can manipulate the visual presentation of web content.
The technical exploitation of this vulnerability relies on the ability of remote attackers to create borderless XUL pop-up windows that appear to be part of legitimate web forms while actually being controlled by malicious code. These pop-up windows can be triggered from background tabs, allowing attackers to craft deceptive interfaces that mimic genuine form elements such as login fields, password prompts, or other interactive components. The flaw enables attackers to intercept user inputs by positioning these malicious elements in strategic locations where users might naturally interact with them, effectively creating a man-in-the-middle scenario without requiring any user interaction beyond normal browsing behavior.
This vulnerability operates at the intersection of several security domains including browser sandboxing, user interface security, and input validation. The attack vector specifically targets the browser's rendering engine's handling of XUL windows, which are designed to provide rich user interfaces but become dangerous when improperly constrained. The issue is classified under CWE-200, which deals with information exposure, as it allows attackers to potentially capture sensitive user input. Additionally, this vulnerability aligns with ATT&CK technique T1177 which covers browser session management and credential theft through UI deception, making it particularly dangerous in phishing and credential harvesting attacks.
The operational impact of this vulnerability extends beyond simple form spoofing to encompass broader security implications for user trust and browser integrity. Users may unknowingly enter sensitive information into what appears to be a legitimate form, while the browser's security model fails to properly distinguish between genuine and malicious interface elements. This creates a significant risk for financial transactions, account logins, and other sensitive operations where user input validation becomes compromised. The background tab execution aspect means that users can be attacked without any visible warning or indication of malicious activity, as the pop-up windows can be generated silently in the background.
Organizations and individual users must implement multiple layers of defense against this vulnerability. The most direct mitigation involves updating to patched versions of Firefox and SeaMonkey, specifically Firefox 2.0.0.13 and SeaMonkey 1.1.9 or later. Browser security policies should include restrictions on XUL window creation and background tab execution. Additionally, user education regarding suspicious interface elements and the importance of verifying URLs before entering sensitive information remains crucial. Network monitoring solutions should be configured to detect unusual XUL-related activities, and browser security extensions that enhance UI validation can provide additional protection layers. The vulnerability demonstrates the importance of maintaining current security patches and highlights the critical need for robust browser sandboxing mechanisms that prevent malicious code from manipulating user interface elements in ways that compromise user security and trust.