CVE-2001-0722 in Internet Explorer
Summary
by MITRE
Internet Explorer 5.5 and 6.0 allows remote attackers to read and modify user cookies via Javascript in an about: URL, aka the "First Cookie Handling Vulnerability."
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Analysis
by VulDB Data Team • 04/02/2025
The vulnerability identified as CVE-2001-0722 represents a critical security flaw in Microsoft Internet Explorer versions 5.5 and 6.0 that fundamentally compromised user session management and privacy. This vulnerability specifically targeted the browser's handling of cookies within the about: protocol namespace, creating an unintended pathway for malicious actors to access and manipulate user authentication tokens. The issue stems from the browser's improper isolation mechanisms between the about: URLs and the regular web browsing environment, allowing JavaScript executed in about: contexts to interact with the user's cookie storage system.
The technical exploitation of this vulnerability occurs through the manipulation of JavaScript code within about: URLs, which are special browser addresses designed to provide access to browser internals and configuration information. When Internet Explorer processes JavaScript within these about: contexts, it fails to properly enforce the same security restrictions that typically apply to regular web pages, enabling attackers to read and modify cookies that should remain protected from cross-site scripting attacks. This flaw essentially bypasses the browser's cookie security model, allowing unauthorized access to session identifiers, authentication tokens, and other sensitive user data that would normally be restricted to the originating domain.
The operational impact of this vulnerability extends far beyond simple information disclosure, as it enables sophisticated attacks including session hijacking, cross-site request forgery, and unauthorized account access. Attackers could craft malicious web pages that, when visited by victims, would automatically extract cookies from the victim's browser and potentially modify them to establish unauthorized sessions. This vulnerability particularly affected users of web applications that relied heavily on cookie-based authentication, making it a significant threat to online banking, email services, and other sensitive web applications. The vulnerability's classification under CWE-200 (Information Exposure) and its alignment with ATT&CK technique T1531 (Account Access Removal) highlights its potential for both data theft and account compromise.
Mitigation strategies for this vulnerability required immediate patching of affected Internet Explorer versions, as Microsoft released security updates to address the cookie handling inconsistency. Organizations needed to implement comprehensive browser security policies that restricted access to about: URLs and enforced strict cookie security settings. The vulnerability also underscored the importance of proper protocol isolation and reinforced the need for robust security boundaries within web browsers. Security professionals recommended implementing additional monitoring for suspicious cookie access patterns and deploying web application firewalls to detect and prevent exploitation attempts. This vulnerability served as a critical learning moment for browser vendors regarding the importance of maintaining strict security boundaries between different protocol contexts and highlighted the necessity of comprehensive security testing for all browser components, particularly those handling user authentication data.