CVE-2001-0898 in Web Browser
Summary
by MITRE
Opera 6.0 and earlier allows remote attackers to access sensitive information such as cookies and links for other domains via Javascript that uses setTimeout to (1) access data after a new window to the domain has been opened or (2) access data via about:cache.
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Analysis
by VulDB Data Team • 04/27/2025
This vulnerability exists in Opera 6.0 and earlier versions due to insufficient security boundaries within the browser's javascript execution environment. The flaw stems from the browser's failure to properly isolate javascript contexts when dealing with cross-domain operations, creating a security loophole that allows malicious code to exploit timing-based access patterns. The vulnerability specifically targets the browser's handling of the setTimeout javascript function which enables delayed execution of code, combined with the browser's cache management system. When a malicious javascript payload executes setTimeout to defer its actions, it can access sensitive data from other domains that would normally be restricted by the same-origin policy.
The technical implementation of this vulnerability relies on the browser's asynchronous execution model and cache access mechanisms. Attackers can craft javascript code that opens a new window to a target domain and then uses setTimeout to defer access to that window's data until after the window has been initialized. Additionally, the vulnerability exploits access to the about:cache pseudo-protocol which provides internal browser cache information. This cache access allows attackers to retrieve cookies and other sensitive data that should be protected from cross-domain javascript access. The timing aspect is crucial because it allows the malicious code to execute after the browser has completed its internal initialization processes, bypassing runtime security checks that would normally prevent such access.
The operational impact of this vulnerability is significant as it enables attackers to perform cross-domain data theft and session hijacking attacks. An attacker could potentially steal authentication cookies from other domains, access private links and resources, and gather sensitive information about user sessions and browsing activities. This creates a persistent threat where attackers can maintain access to user sessions across multiple domains, effectively breaking the fundamental security boundary that separates different web origins. The vulnerability is particularly dangerous because it can be exploited through standard web pages without requiring any special privileges or user interaction beyond visiting the malicious site.
This vulnerability maps to CWE-200 (Information Exposure) and CWE-352 (Cross-Site Request Forgery) categories within the CWE taxonomy, representing a classic case of insufficient access control and information leakage. The attack pattern aligns with ATT&CK technique T1056.001 (Input Capture) and T1566 (Phishing) as attackers can use this vulnerability to capture user credentials and session information. The weakness exists in the browser's implementation of the same-origin policy enforcement, specifically in how it handles asynchronous javascript execution and cache access. Mitigation strategies should focus on implementing proper context isolation for javascript execution, strengthening the same-origin policy enforcement mechanisms, and preventing access to internal browser cache information through javascript. Browser vendors should ensure that setTimeout and similar asynchronous execution functions do not allow access to resources that would normally be restricted by cross-domain security policies, and that internal browser protocols like about:cache are properly protected from unauthorized javascript access.