CVE-2001-1491 in Web Browser
Summary
by MITRE
Opera 5.11 allows remote attackers to cause a denial of service (CPU consumption and memory leak) via a web page with a large number of images.
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Analysis
by VulDB Data Team • 12/05/2024
This vulnerability affects Opera version 5.11 and represents a classic resource exhaustion attack that exploits the browser's handling of multiple image elements within web pages. The flaw manifests when a malicious web page contains an excessive number of image references, causing the browser to consume excessive cpu cycles and memory resources during rendering. This type of vulnerability falls under the category of resource exhaustion attacks that can be classified as a variant of cwe-400, which deals with uncontrolled resource consumption. The attack vector is particularly effective because it leverages the normal operation of web browsers, which are designed to process and display multiple images simultaneously. When the browser encounters a page with numerous image elements, it attempts to load and render each image sequentially or in parallel, leading to progressive memory allocation and cpu utilization that can eventually cause the browser to become unresponsive or crash entirely.
The operational impact of this vulnerability extends beyond simple denial of service to include potential system instability and performance degradation. Attackers can craft web pages containing hundreds or thousands of image references, each pointing to either valid images or to non-existent resources, creating a scenario where the browser's memory management system becomes overwhelmed. This behavior aligns with attack techniques documented in the attack pattern taxonomy under the category of resource exhaustion attacks. The vulnerability is particularly concerning because it does not require any special privileges or authentication to exploit, making it accessible to anyone who can deliver a malicious webpage to an affected user. The memory leak component of this vulnerability means that even if the browser recovers from the immediate resource exhaustion, the leaked memory may not be properly reclaimed, leading to progressive degradation of system performance over time.
Mitigation strategies for this vulnerability should focus on implementing robust resource management and limiting mechanisms within the browser's rendering engine. Browser vendors should implement maximum image count limits per page, establish memory usage thresholds that trigger automatic cleanup processes, and implement more efficient image loading algorithms that can detect and handle excessive image requests. The implementation of these protections should align with security best practices outlined in industry standards such as the owasp top ten and nist cybersecurity framework. Users can protect themselves by keeping their browsers updated, avoiding untrusted websites, and employing browser security extensions that can monitor and limit resource consumption. Additionally, system administrators should consider implementing network-level controls that can detect and block suspicious traffic patterns associated with resource exhaustion attacks, particularly in environments where multiple users share the same network infrastructure. The vulnerability demonstrates the importance of proper input validation and resource management in web browser implementations, as it highlights how seemingly benign web content can be weaponized to cause system instability.