CVE-2007-3089 in Firefox
Summary
by MITRE
Mozilla Firefox before 2.0.0.5 does not prevent use of document.write to replace an IFRAME (1) during the load stage or (2) in the case of an about:blank frame, which allows remote attackers to display arbitrary HTML or execute certain JavaScript code, as demonstrated by code that intercepts keystroke values from window.event, aka the "promiscuous IFRAME access bug," a related issue to CVE-2006-4568.
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Analysis
by VulDB Data Team • 01/13/2025
The vulnerability identified as CVE-2007-3089 represents a significant security flaw in Mozilla Firefox versions prior to 2.0.0.5 that relates to improper handling of document.write operations within IFRAME elements during specific loading stages. This weakness stems from Firefox's inadequate restriction mechanisms when processing document.write calls that attempt to replace IFRAME content, creating a potential attack vector for remote code execution and data interception. The issue manifests when the browser allows document.write to modify IFRAME elements either during their initial loading phase or specifically when dealing with about:blank frames, which fundamentally undermines the security boundaries that should normally protect against such cross-context modifications.
The technical implementation of this vulnerability exploits the browser's failure to properly enforce security policies when document.write operations target IFRAME elements during their lifecycle. During the load stage of an IFRAME, the browser should maintain strict isolation between the parent document and the embedded content, yet this flaw permits malicious scripts to bypass these protections. The vulnerability specifically affects scenarios where document.write attempts to replace an IFRAME's content, allowing attackers to inject arbitrary HTML and execute JavaScript code within the context of the target frame. This behavior creates a situation where keystroke interception becomes possible through window.event manipulation, as demonstrated by the attack vectors that exploit this weakness.
The operational impact of CVE-2007-3089 extends beyond simple cross-site scripting attacks, as it enables sophisticated phishing and credential theft operations. Attackers can leverage this vulnerability to create deceptive IFRAME content that appears legitimate while simultaneously capturing user input through keystroke interception techniques. The promiscuous nature of IFRAME access means that malicious actors can manipulate frame content even when the frame is in an about:blank state, which is typically considered a safe context for initial loading. This vulnerability directly relates to the broader category of cross-site scripting attacks and represents a failure in browser sandboxing mechanisms that should prevent such unauthorized content modifications.
This security flaw aligns with CWE-79, which addresses cross-site scripting vulnerabilities, and demonstrates weaknesses in input validation and output encoding within web browsers. The vulnerability also connects to ATT&CK technique T1059.007, which covers JavaScript execution, and T1566, which encompasses phishing attacks that leverage web-based exploits. The attack surface is particularly concerning because it allows for the execution of arbitrary code in the context of a victim's browser session, potentially enabling session hijacking, credential theft, and other malicious activities. The vulnerability essentially creates a pathway for attackers to circumvent the same-origin policy that normally protects against unauthorized access to IFRAME content, making it a critical issue for browser security implementations.
Mitigation strategies for CVE-2007-3089 require immediate browser updates to version 2.0.0.5 or later, where Mozilla implemented proper restrictions on document.write operations within IFRAME contexts. Organizations should also implement network-level protections such as content filtering solutions that can detect and block malicious IFRAME content, while security teams should monitor for exploitation attempts through web application firewalls. The fix implemented by Mozilla involved strengthening the security boundaries around IFRAME content modification during loading stages, ensuring that document.write operations cannot replace or modify IFRAME content in ways that would compromise security. Additionally, browser security policies should include enhanced sandboxing measures that prevent unauthorized access to IFRAME contexts, particularly during critical loading phases where content replacement operations are most dangerous.