CVE-2007-3091 in Internet Explorer
Summary
by MITRE
Race condition in Microsoft Internet Explorer 6 SP1; 6 and 7 for Windows XP SP2 and SP3; 6 and 7 for Server 2003 SP2; 7 for Vista Gold, SP1, and SP2; and 7 for Server 2008 SP2 allows remote attackers to execute arbitrary code or perform other actions upon a page transition, with the permissions of the old page and the content of the new page, as demonstrated by setInterval functions that set location.href within a try/catch expression, aka the "bait & switch vulnerability" or "Race Condition Cross-Domain Information Disclosure Vulnerability."
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Analysis
by VulDB Data Team • 01/25/2025
The CVE-2007-3091 vulnerability represents a critical race condition flaw in Microsoft Internet Explorer versions 6 through 7 across multiple Windows operating systems. This vulnerability operates at the intersection of browser security mechanisms and timing-sensitive operations, creating a window where malicious actors can exploit the temporal gap between page transitions to execute unauthorized actions. The flaw specifically manifests when Internet Explorer handles page navigation events, particularly when transitioning between pages during asynchronous operations, allowing attackers to manipulate the execution context and gain access to sensitive information from the previous page while executing code with the permissions of that page's security context.
The technical implementation of this vulnerability relies on the browser's handling of JavaScript execution contexts during navigation events. When a page transition occurs, particularly involving location.href changes within try/catch blocks, the browser's race condition allows an attacker to inject code that executes in the context of the previous page's security domain while potentially accessing data from the new page. This creates a scenario where attackers can perform what is known as a "bait and switch" attack, where they manipulate the browser's state during page transitions to execute malicious code with elevated privileges. The vulnerability specifically affects how Internet Explorer manages the execution context during asynchronous operations and page navigation, creating a temporal gap where security boundaries can be circumvented.
The operational impact of this vulnerability extends beyond simple code execution to include significant cross-domain information disclosure capabilities. Attackers can leverage this race condition to access sensitive data from different security domains, potentially extracting information that should be isolated between different websites or applications. This vulnerability is particularly dangerous because it operates at the browser level and can be exploited through standard web pages without requiring special privileges or user interaction beyond visiting a malicious site. The attack vector typically involves crafting malicious JavaScript that takes advantage of the timing window during page transitions, making it particularly challenging to detect and prevent through traditional security measures.
This vulnerability maps directly to CWE-367, which describes the Time-of-Check to Time-of-Use (TOCTOU) flaw, and aligns with ATT&CK technique T1059.007 for JavaScript execution. The exploit demonstrates how timing vulnerabilities can be weaponized to bypass security controls that normally protect against cross-site scripting attacks. Microsoft addressed this vulnerability through security updates that modified how Internet Explorer handles page transition events and execution contexts during navigation, implementing additional synchronization mechanisms to prevent the race condition from being exploited. Organizations should ensure all affected Internet Explorer versions are updated with the latest security patches and consider implementing additional browser security measures such as content security policies and sandboxing techniques to mitigate the risk of exploitation.
The broader implications of this vulnerability highlight the complexity of modern browser security and the challenges of maintaining secure execution contexts during asynchronous operations. This flaw demonstrates how seemingly benign browser features like page transitions can become attack vectors when not properly synchronized with security mechanisms. The vulnerability also underscores the importance of comprehensive testing for race conditions in security-critical applications and the need for robust temporal consistency checks in web browser implementations. Security professionals should recognize that such vulnerabilities often require deep understanding of browser internals and timing-sensitive operations to both detect and remediate effectively.