CVE-2010-5071 in Internet Explorer
Summary
by MITRE
The JavaScript implementation in Microsoft Internet Explorer 8.0 and earlier does not properly restrict the set of values contained in the object returned by the getComputedStyle method, which allows remote attackers to obtain sensitive information about visited web pages by calling this method.
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Analysis
by VulDB Data Team • 11/27/2021
The vulnerability described in CVE-2010-5071 represents a significant information disclosure flaw within Microsoft Internet Explorer 8.0 and earlier versions that exploits the JavaScript implementation's improper handling of the getComputedStyle method. This weakness specifically targets the browser's JavaScript engine where the getComputedStyle method fails to adequately restrict the values it returns when processing CSS properties of visited web pages. The flaw enables attackers to extract sensitive information about a user's browsing history and visited websites through carefully crafted JavaScript code that leverages this method.
The technical implementation of this vulnerability stems from the improper sanitization and validation of CSS property values returned by the getComputedStyle method in Internet Explorer's JavaScript engine. When a web page calls getComputedStyle on an element, the method should return a read-only object containing computed style properties that are relevant to the element's visual presentation. However, in affected versions of Internet Explorer, the implementation fails to properly restrict the scope of values that can be accessed through this method, creating a potential information leakage channel that can be exploited by malicious actors.
The operational impact of this vulnerability is particularly concerning as it enables remote attackers to perform passive reconnaissance of user browsing behavior without requiring any user interaction or explicit consent. Attackers can construct malicious web pages that, when visited by a victim using an affected browser version, can extract information about previously visited sites through the getComputedStyle method. This capability directly violates user privacy expectations and creates a persistent surveillance channel that can be exploited across multiple browsing sessions. The vulnerability aligns with CWE-200, which classifies information exposure vulnerabilities, and demonstrates how seemingly benign browser APIs can be weaponized for privacy violations.
The attack vector for this vulnerability operates through web-based exploitation where malicious websites can execute JavaScript code that calls getComputedStyle on targeted elements and analyzes the returned property values to infer information about visited pages. This technique can be particularly effective in cross-site scripting scenarios or when users are browsing compromised websites, as the attacker can leverage the browser's own JavaScript capabilities against the user's session. The vulnerability's impact extends beyond simple privacy concerns as it can enable more sophisticated attacks such as tracking user behavior across different domains or identifying sensitive websites that users have visited, which could be leveraged for targeted phishing or social engineering attacks.
Security professionals should consider this vulnerability in the context of the ATT&CK framework's information gathering tactics, where adversaries can use browser-based techniques to collect intelligence about user activities. The recommended mitigations include updating to Microsoft Internet Explorer 9.0 or later versions where this vulnerability has been addressed, implementing proper browser security policies, and utilizing content security policies to limit the execution of potentially malicious JavaScript code. Additionally, users should be educated about the risks of visiting untrusted websites and the importance of keeping their browsers updated to protect against such information disclosure vulnerabilities. Organizations should also consider implementing web application firewalls and monitoring for suspicious JavaScript behavior that attempts to access CSS properties in ways that could indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation and output sanitization in browser implementations and serves as a reminder of how subtle implementation flaws in core browser APIs can create significant security risks.