CVE-2007-3511 in Firefox
Summary
by MITRE
The focus handling for the onkeydown event in Mozilla Firefox 1.5.0.12, 2.0.0.4 and other versions before 2.0.0.8, and SeaMonkey before 1.1.5 allows remote attackers to change field focus and copy keystrokes via the "for" attribute in a label, which bypasses the focus prevention, as demonstrated by changing focus from a textarea to a file upload field.
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Analysis
by VulDB Data Team • 07/29/2019
This vulnerability represents a significant focus management flaw in web browser security implementations that affects mozilla firefox versions prior to 2.0.0.8 and seamoon before 1.1.5. The issue stems from improper handling of the onkeydown event when processing label elements with the "for" attribute, creating an unexpected behavior that allows malicious actors to manipulate focus traversal and keystroke capture mechanisms. The vulnerability specifically exploits the relationship between label elements and form controls, where the label's for attribute should normally provide accessibility linking but instead becomes a vector for security bypass. This flaw operates at the intersection of user interface event handling and security boundary enforcement, where the browser's focus prevention mechanisms are circumvented through crafted html structures.
The technical execution of this vulnerability involves leveraging the label element's association with form controls to manipulate the browser's focus management system during keyboard input events. When a user interacts with a textarea element, the maliciously constructed label with for attribute can redirect focus to a file upload field while simultaneously capturing keystrokes intended for the original element. This creates a scenario where keystrokes can be intercepted and potentially exfiltrated from one field while appearing to be entered into another, effectively bypassing the browser's intended focus prevention controls. The vulnerability demonstrates a classic case of improper input validation and event handling where the browser fails to properly validate the security implications of label element associations during keyboard event processing.
The operational impact of this vulnerability extends beyond simple keystroke interception to potentially enable more sophisticated attacks such as credential harvesting, data exfiltration, and session manipulation. Attackers can construct malicious pages that appear benign to users while silently redirecting focus to sensitive input fields like password or credit card fields, capturing input data without user awareness. This type of vulnerability aligns with attack patterns documented in the attack tree framework where focus manipulation can lead to privilege escalation or data compromise. The security implications are particularly severe in contexts where users interact with web applications that process sensitive data, as the attack can be executed remotely without requiring user interaction beyond visiting a malicious website.
This vulnerability maps directly to CWE-200, which addresses improper output handling and information exposure, and also relates to CWE-352, concerning cross-site request forgery, though more specifically it represents a focus management bypass issue. From an ATT&CK perspective, this vulnerability aligns with T1056.001, which covers input injection techniques, and T1555.003, which deals with credential access through keylogging mechanisms. The attack surface is particularly concerning in enterprise environments where users may interact with multiple web applications, as the vulnerability can be exploited across different domains and applications without requiring additional privileges. Organizations should implement immediate mitigations including browser updates, content security policy enforcement, and user education about visiting untrusted websites. The vulnerability also underscores the importance of proper event handling and focus management in web browser implementations, where accessibility features should not inadvertently create security weaknesses. Regular security assessments and vulnerability scanning should include verification of focus handling mechanisms in web browsers to prevent similar issues from being exploited in production environments.