CVE-2001-0002 in Internet Explorer
Summary
by MITRE
Internet Explorer 5.5 and earlier allows remote attackers to obtain the physical location of cached content and open the content in the Local Computer Zone, then use compiled HTML help (.chm) files to execute arbitrary programs.
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Analysis
by VulDB Data Team • 06/25/2021
This vulnerability resides in the Microsoft Internet Explorer browser version 5.5 and earlier, representing a significant security flaw that exploited the browser's handling of cached content and zone permissions. The issue stems from how Internet Explorer managed the local computer zone access when cached content was retrieved, creating an avenue for remote attackers to manipulate the browser's security model. The vulnerability specifically targeted the interaction between cached content storage mechanisms and the browser's zone-based security policies, allowing attackers to elevate privileges through a carefully crafted attack vector that leveraged both caching behavior and zone assignment logic.
The technical exploitation mechanism involved leveraging the browser's caching system to store content in a manner that would subsequently be interpreted as originating from the local computer zone. This occurred because Internet Explorer did not properly validate the source of cached content when determining zone assignment, enabling attackers to manipulate the security context under which cached files would execute. The flaw was particularly dangerous because it allowed attackers to use compiled HTML help files with the .chm extension to execute arbitrary code on the victim's system. The .chm file format, while designed for help documentation, could be manipulated to contain executable content due to the browser's trust relationship with cached files in the local computer zone, creating a pathway for privilege escalation and code execution.
The operational impact of this vulnerability was substantial as it enabled attackers to bypass the browser's security model and execute malicious code with the privileges of the local user. The attack required remote access to the victim's system and involved tricking the browser into caching malicious content that would then be executed in a trusted context. This created a persistent threat vector that could be exploited across multiple sessions and potentially lead to complete system compromise. The vulnerability represented a classic case of privilege escalation through zone manipulation and caching abuse, allowing attackers to leverage legitimate browser functionality against its own security controls.
Mitigation strategies for this vulnerability required immediate patching of Internet Explorer to version 5.5 Service Pack 2 or later, which addressed the core caching and zone assignment logic flaws. System administrators should have implemented browser security policies that restricted .chm file execution and disabled unnecessary caching behaviors that could be exploited. The vulnerability aligns with CWE-22, which covers improper limitation of a pathname to a restricted directory, and CWE-74, which addresses injection flaws. From an attack framework perspective, this vulnerability would be categorized under the ATT&CK technique T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, demonstrating how browser-based vulnerabilities can be leveraged for system compromise. Organizations needed to implement network monitoring to detect unusual caching behavior and .chm file execution patterns, while also ensuring proper browser updates and security configuration management to prevent exploitation of similar vulnerabilities in other browser components.