CVE-2016-0162 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 9 through 11 allows remote attackers to determine the existence of files via crafted JavaScript code, aka "Internet Explorer Information Disclosure Vulnerability."
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Analysis
by VulDB Data Team • 04/23/2026
Microsoft Internet Explorer versions 9 through 11 contained a critical information disclosure vulnerability that enabled remote attackers to infer the existence of specific files on a target system through carefully constructed JavaScript code. This vulnerability falls under the Common Weakness Enumeration category CWE-200, which describes weaknesses that lead to information exposure, and represents a classic example of how browser implementations can inadvertently leak sensitive information through side-channel attacks. The flaw specifically manifested when Internet Explorer processed certain JavaScript constructs that would trigger different error behaviors based on whether a file existed at a particular location within the file system. When attackers could observe these distinct error responses or timing variations in the browser's behavior, they could deduce whether specific files were present, effectively creating a file enumeration mechanism that bypassed normal file system access controls.
The technical implementation of this vulnerability exploited the way Internet Explorer handled file access operations within its JavaScript engine. Attackers could craft malicious scripts that attempted to access files through various methods such as XMLHttpRequest or ActiveXObject interfaces, which would produce different error codes or behaviors depending on whether the target file existed. This information disclosure occurred because the browser's security model did not properly isolate file system access operations from JavaScript execution contexts, allowing the underlying file system state to be inferred through observable program behavior. The vulnerability was particularly dangerous because it could be exploited through web pages loaded in the browser, meaning users could unknowingly expose file system information simply by visiting compromised websites. The attack vector demonstrated the fundamental principle of information leakage through timing side channels and error response variations, which are common patterns in software security vulnerabilities.
The operational impact of this vulnerability was significant for organizations relying on Internet Explorer for business operations, as it provided attackers with a method to perform reconnaissance without direct system access. Attackers could use this information to map file structures on targeted systems, identify sensitive files, and potentially combine this information with other exploitation techniques to create more sophisticated attacks. The vulnerability affected all supported versions of Internet Explorer from version 9 through 11, representing a broad attack surface across multiple operating system versions including Windows 7, Windows 8, Windows 8.1, and Windows Server 2008 R2. Organizations using these browsers faced the risk of unauthorized file enumeration, which could lead to information disclosure of user data, system configuration files, or other sensitive resources stored on the target systems. This vulnerability also demonstrated the importance of proper error handling and the need for security-conscious programming practices when implementing file system operations in web browsers.
Microsoft addressed this vulnerability through security updates released as part of their regular patching cycle, with the fix implemented in the browser's JavaScript engine to prevent the leakage of file existence information. Organizations should have implemented immediate patches and considered alternative browser solutions for environments where the risk was particularly high. The vulnerability highlighted the importance of comprehensive security testing, including side-channel attack analysis, during software development processes. Security professionals should have conducted vulnerability assessments to identify similar patterns in other browser implementations and ensured that error handling mechanisms properly abstracted underlying system state information. This case study exemplifies the broader security principle that seemingly benign features in software can create exploitable information leakage pathways, reinforcing the need for defensive programming practices and comprehensive security architecture reviews. The vulnerability also demonstrated the importance of maintaining up-to-date browser security patches and implementing browser hardening measures to reduce the attack surface for such information disclosure vulnerabilities.