CVE-2007-3497 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 7 allows remote attackers to determine the existence of page history via the history.length JavaScript variable.
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Analysis
by VulDB Data Team • 07/20/2021
This vulnerability in Microsoft Internet Explorer 7 represents a significant information disclosure flaw that exploits the browser's handling of the history.length JavaScript variable. The issue stems from the browser's implementation of the Document Object Model where the history.length property can be accessed through JavaScript to infer whether specific URLs have been visited in the user's browsing history. Attackers can leverage this functionality to perform passive reconnaissance by observing the behavior of the history.length variable when navigating between different pages, particularly when certain pages are accessed via links or direct navigation.
The technical exploitation occurs through JavaScript code that manipulates the history object and observes the returned length values. When a user navigates to a page that has been previously visited, the history.length property returns a different value compared to when the same page is accessed for the first time. This differential behavior allows attackers to determine the existence of specific URLs in a user's browsing history without requiring direct access to the history object itself. The vulnerability specifically affects Internet Explorer 7 and earlier versions, as the browser's JavaScript engine and history management implementation contained this information leakage mechanism.
The operational impact of this vulnerability extends beyond simple information gathering and represents a privacy concern that can be exploited in various attack scenarios. Security researchers have classified this as a weakness that enables tracking of user behavior patterns and browsing habits through passive observation techniques. The vulnerability can be particularly dangerous when combined with other tracking methods, as it provides additional data points for profiling user activities. This information leakage could potentially be used in social engineering attacks, targeted advertising, or more sophisticated tracking mechanisms that monitor user behavior across different websites.
This vulnerability aligns with CWE-200, which describes information exposure through information leakage, and demonstrates how browser implementations can inadvertently expose sensitive user data through seemingly benign JavaScript APIs. The issue also relates to ATT&CK technique T1566, specifically the sub-technique T1566.001 for spearphishing attachments, as attackers could potentially use this information to craft more convincing phishing attempts by understanding a user's browsing patterns and interests. Additionally, the vulnerability connects to T1580 for adversary use of information discovery techniques, as it provides an automated method for gathering information about a target's online activities.
The recommended mitigations for this vulnerability involve both browser updates and code-level protections. Microsoft addressed this issue through security updates that modified how the history.length property behaves in JavaScript, preventing the leakage of browsing history information. Organizations should ensure that all Internet Explorer installations are updated to the latest security patches, as the vulnerability only affects older versions of the browser. Developers should also implement proper input validation and avoid relying on JavaScript history APIs for sensitive operations, while security-conscious organizations can consider implementing browser security policies that restrict access to certain JavaScript objects or properties. The vulnerability underscores the importance of secure browser implementation practices and the need for thorough security testing of JavaScript APIs that interact with browser history and navigation mechanisms.