CVE-2009-3933 in WebKit
Summary
by MITRE
WebKit before r50173, as used in Google Chrome before 3.0.195.32, allows remote attackers to cause a denial of service (CPU consumption) via a web page that calls the JavaScript setInterval method, which triggers an incompatibility between the WTF::currentTime and base::Time functions.
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Analysis
by VulDB Data Team • 05/26/2025
The vulnerability identified as CVE-2009-3933 represents a critical denial of service flaw within the WebKit rendering engine that was prevalent in Google Chrome versions prior to 3.0.195.32. This issue stems from an incompatibility between two core time management functions within the WebKit codebase, specifically the WTF::currentTime and base::Time functions. The vulnerability manifests when a malicious web page executes JavaScript code that repeatedly calls the setInterval method, creating a scenario where the system's CPU resources become consumed excessively.
The technical root cause of this vulnerability lies in the improper handling of time calculations within WebKit's internal time management subsystem. When JavaScript's setInterval function is invoked repeatedly, it triggers a cascade of calls to these incompatible time functions that were designed to operate under different assumptions about time measurement and system clock behavior. The WTF::currentTime function, which is part of WebKit's internal utilities, and the base::Time function, which provides time-related functionality for the browser's core components, exhibit conflicting behaviors when processing time values, particularly around boundary conditions and system clock adjustments.
This incompatibility creates a condition where the system's CPU utilization spikes dramatically as the browser attempts to process time-related operations in an infinite loop. The malicious web page essentially forces the browser to continuously perform time calculations that either become increasingly expensive or enter into an infinite loop, depending on how the incompatible functions interact. The vulnerability is particularly dangerous because it can be triggered through standard web browsing activities without requiring any special privileges or user interaction beyond visiting the malicious page.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it can effectively render the affected browser instance unusable for extended periods. Users may experience complete system slowdowns or complete browser crashes, making it difficult to perform normal web browsing activities. This type of denial of service attack can be particularly effective in environments where users rely heavily on browser-based applications or when the vulnerability is exploited in conjunction with other attack vectors.
The vulnerability aligns with CWE-400, which describes unrestricted resource consumption, and demonstrates how improper handling of system resources can lead to complete service disruption. From an ATT&CK perspective, this vulnerability falls under the T1499.004 technique for "Resource Hijacking" and represents a classic example of how seemingly minor implementation flaws can be exploited to create significant operational impact. The vulnerability also relates to T1566.001 for "Phishing" as it can be delivered through malicious web pages that trick users into visiting compromised sites.
Mitigation strategies for this vulnerability include updating to Google Chrome version 3.0.195.32 or later, which contains the necessary patches to resolve the time function incompatibility. Browser vendors should implement robust time handling mechanisms that prevent such incompatibilities from occurring in the first place, particularly when integrating third-party libraries or components that may have different assumptions about time measurement. Additionally, web application developers should be aware of the potential for such timing-related vulnerabilities in their own code and implement proper error handling and resource management techniques to prevent similar issues from occurring in their applications.