CVE-2001-1219 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6.0 and earlier allows malicious website operators to cause a denial of service (client crash) via JavaScript that continually refreshes the window via self.location.
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Analysis
by VulDB Data Team • 04/07/2017
Microsoft Internet Explorer versions 6.0 and earlier contain a critical vulnerability that enables malicious actors to execute denial of service attacks through carefully crafted JavaScript code. This vulnerability specifically exploits the browser's handling of window refresh operations, allowing attackers to create infinite loops that consume excessive system resources and ultimately crash the client application. The flaw occurs when JavaScript code repeatedly invokes self.location or similar refresh mechanisms, creating an unbreakable loop that exhausts memory and processor cycles.
The technical implementation of this vulnerability resides in the browser's JavaScript engine and window management subsystem. When a malicious script executes self.location.refresh() or equivalent commands in rapid succession, the browser's rendering engine becomes overwhelmed with processing requests that cannot be properly terminated. This behavior represents a classic resource exhaustion attack pattern that aligns with common attack techniques documented in the attack framework. The vulnerability demonstrates poor input validation and lack of loop detection mechanisms within the browser's JavaScript execution environment.
From an operational perspective, this vulnerability poses significant risk to users who may inadvertently visit compromised websites or click on malicious links. The attack requires no special privileges or complex exploitation techniques, making it particularly dangerous as it can be executed through simple web page content. The client-side nature of the vulnerability means that any user with Internet Explorer 6.0 or earlier installed becomes immediately vulnerable, regardless of their security awareness or system configuration. This makes it an attractive target for mass deployment attacks and automated exploitation campaigns.
The impact of this vulnerability extends beyond simple browser crashes to potentially affect system stability and user productivity. When the browser crashes, users lose unsaved work and may experience system-wide performance degradation as the operating system attempts to recover from the application failure. The vulnerability also represents a failure in proper resource management and error handling within the browser's JavaScript execution environment, which should have implemented safeguards against infinite loops and excessive resource consumption. Organizations deploying older Internet Explorer versions face heightened risk of service disruption and increased support overhead due to this vulnerability.
Security mitigations for this vulnerability primarily focus on immediate browser upgrades to patched versions or newer Internet Explorer releases that address the JavaScript execution flaws. Users should also implement browser security settings that limit JavaScript execution or disable automatic refresh behaviors. Network-level protections such as web application firewalls can help detect and block malicious JavaScript patterns, though these solutions are less effective against client-side vulnerabilities. The vulnerability serves as a reminder of the importance of regular security updates and proper resource management in browser implementations. Organizations should prioritize migrating away from unsupported browser versions to reduce exposure to similar vulnerabilities and ensure compliance with modern security standards. This issue highlights the need for robust input validation and execution limits in web browsers, principles that align with established security frameworks and best practices for preventing resource exhaustion attacks.