CVE-2008-5821 in Safari
Summary
by MITRE
Memory leak in WebKit.dll in WebKit, as used by Apple Safari 3.2 on Windows Vista SP1, allows remote attackers to cause a denial of service (memory consumption and browser crash) via a long ALINK attribute in a BODY element in an HTML document.
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Analysis
by VulDB Data Team • 02/19/2025
The vulnerability identified as CVE-2008-5821 represents a critical memory management flaw within the WebKit rendering engine component that powers Apple Safari 3.2 on Windows Vista SP1 systems. This issue manifests as a memory leak in the WebKit.dll library, which is responsible for processing and rendering web content in the browser environment. The vulnerability specifically targets the handling of the ALINK attribute within HTML BODY elements, demonstrating a classic buffer management failure that can be exploited remotely by malicious actors. The flaw operates at the core level of web browser functionality, where improper memory allocation and deallocation routines create persistent memory consumption issues that degrade system performance and ultimately lead to application instability.
The technical implementation of this vulnerability exploits the manner in which WebKit processes HTML attributes, particularly focusing on the ALINK attribute that defines the color of active links within a document. When a malicious HTML document contains an excessively long ALINK attribute value within a BODY element, the WebKit engine fails to properly manage the memory allocation required to process this malformed input. This memory leak occurs because the rendering engine does not correctly handle the boundary conditions of attribute parsing, leading to continuous memory consumption without proper garbage collection. The vulnerability falls under the CWE-401 weakness category, specifically addressing improper handling of memory allocation and deallocation operations, which creates a persistent resource exhaustion condition that can be amplified through repeated exploitation attempts.
The operational impact of this vulnerability extends beyond simple denial of service to create significant security implications for users operating vulnerable Safari versions on Windows Vista systems. Remote attackers can leverage this flaw to consume increasing amounts of system memory, causing the browser to become unresponsive and eventually crash entirely. This creates an environment where legitimate users experience service disruption while malicious actors can effectively deny access to web browsing functionality for extended periods. The vulnerability's exploitation requires no special privileges or user interaction beyond visiting a malicious webpage, making it particularly dangerous as it can be automated and deployed at scale. According to ATT&CK framework methodology, this represents a privilege escalation vector through resource exhaustion, classified under the T1499 technique for network denial of service attacks, where the attacker manipulates system resources to compromise availability.
Mitigation strategies for CVE-2008-5821 primarily focus on immediate software updates and patches provided by Apple to address the underlying memory management issues in WebKit.dll. System administrators should prioritize updating Safari to versions that include proper memory handling routines and attribute validation for HTML elements. Additionally, implementing network-level protections such as web application firewalls and content filtering systems can help prevent access to malicious websites containing the vulnerable ALINK attribute constructions. Organizations should also consider deploying browser hardening measures and monitoring for unusual memory consumption patterns that may indicate exploitation attempts. The vulnerability highlights the importance of proper input validation and memory management practices in web rendering engines, emphasizing that even seemingly benign HTML attributes can create critical security weaknesses when not properly constrained and validated against malicious input patterns.