CVE-2009-1530 in Internet Explorer
Summary
by MITRE
Use-after-free vulnerability in Microsoft Internet Explorer 7 for Windows XP SP2 and SP3; 7 for Server 2003 SP2; 7 for Vista Gold, SP1, and SP2; and 7 for Server 2008 SP2 allows remote attackers to execute arbitrary code by repeatedly adding HTML document nodes and calling event handlers, which triggers an access of an object that (1) was not properly initialized or (2) is deleted, aka "HTML Objects Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 03/17/2021
This vulnerability represents a classic use-after-free condition that affects Microsoft Internet Explorer 7 across multiple Windows operating systems including XP SP2 and SP3, Server 2003 SP2, Vista Gold, SP1 and SP2, and Server 2008 SP2. The flaw occurs when the browser processes HTML document nodes through repeated addition operations combined with event handler calls, creating a scenario where memory management becomes compromised. The vulnerability maps directly to CWE-416 which defines use-after-free conditions as a critical memory safety issue where a program continues to reference memory after it has been freed. This particular implementation involves HTML object memory corruption that manifests when the browser attempts to access objects that either were never properly initialized or have already been deleted from memory, creating a dangerous state where arbitrary code execution becomes possible.
The operational impact of this vulnerability extends beyond simple memory corruption to enable remote code execution capabilities that align with ATT&CK technique T1059.1001 for command and script interpreter execution. Attackers can exploit this weakness by crafting malicious web pages that repeatedly manipulate HTML document nodes and trigger event handlers in a manner that forces the browser to access freed memory locations. The exploitation process leverages the browser's memory management routines and specifically targets the object lifecycle management within Internet Explorer's rendering engine, which is particularly concerning given IE7's widespread deployment in enterprise environments. This vulnerability demonstrates how improper memory handling in web browsers can create persistent security risks that remain exploitable across multiple versions and operating system variants.
The technical exploitation requires precise timing and specific HTML manipulation sequences that cause the browser to create and destroy objects in a way that leaves memory references in an inconsistent state. When the event handlers are called repeatedly, they access objects that have been freed but not properly nullified, leading to memory corruption that attackers can leverage to execute arbitrary code with the privileges of the compromised browser process. This vulnerability type represents a fundamental flaw in how Internet Explorer manages object lifecycles and memory deallocation, particularly when handling dynamic HTML content. The risk assessment indicates this vulnerability could be exploited in the wild, as evidenced by its classification and the fact that it affected widely deployed browser versions across different Windows platforms, making it a significant concern for organizations maintaining legacy systems that could not be immediately patched.
Mitigation strategies for this vulnerability should focus on immediate patch deployment as provided by Microsoft security updates, which address the underlying memory management issues in IE7's object handling routines. Organizations should implement browser hardening measures including disabling unnecessary scripting capabilities, implementing content security policies, and utilizing sandboxing techniques to limit the impact of potential exploitation. Network-based protections such as web application firewalls can help detect and block malicious payloads targeting this specific vulnerability. Additionally, regular security assessments and vulnerability scanning should identify systems running unpatched versions of IE7 that remain exposed to this use-after-free condition. The remediation process must also consider the broader implications of legacy browser support, as this vulnerability demonstrates the critical need for organizations to maintain updated browser environments to prevent exploitation of known memory safety issues that can lead to complete system compromise.