CVE-2011-2000 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6 through 9 does not properly handle objects in memory, which allows remote attackers to execute arbitrary code by accessing a deleted object, aka "Body Element Remote Code Execution Vulnerability."
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Analysis
by VulDB Data Team • 11/23/2021
The vulnerability identified as CVE-2011-2000 represents a critical memory corruption flaw in Microsoft Internet Explorer versions 6 through 9 that enables remote code execution through improper object handling in memory. This vulnerability specifically targets the browser's memory management mechanisms when processing web content, creating a scenario where attackers can manipulate memory objects that have already been freed or deleted. The flaw occurs during the processing of HTML elements, particularly the body element, where the browser fails to properly validate object references after memory deallocation. This type of vulnerability falls under the CWE-125 vulnerability category, which describes "Out-of-bounds Read" conditions where programs access memory locations beyond the intended bounds, and more specifically aligns with CWE-476 which addresses "NULL Pointer Dereference" scenarios that can occur when accessing freed memory locations.
The operational impact of this vulnerability is severe as it allows remote attackers to execute arbitrary code on affected systems without requiring user interaction beyond visiting a malicious website. Attackers can craft specially designed web pages that trigger the memory corruption when Internet Explorer processes the page content, leading to potential system compromise and full control over the affected machine. The vulnerability exploits the browser's failure to properly manage object lifecycles in memory, enabling attackers to leverage dangling pointer references that point to memory locations that have been deallocated but not yet overwritten. This memory management flaw creates a persistent attack surface that remains exploitable across multiple Internet Explorer versions, making it particularly dangerous for organizations with legacy browser deployments.
From an attack perspective, this vulnerability maps to several ATT&CK techniques including T1059.001 for command and scripting interpreter, T1566.001 for spearphishing attachment, and T1078.004 for valid accounts. The exploitation process typically involves crafting malicious web content that forces the browser to access deleted memory objects through carefully constructed HTML elements and JavaScript code. The vulnerability demonstrates the classic pattern of use-after-free exploits where the attacker leverages the time gap between object deallocation and memory reuse to inject malicious code into the execution flow. Organizations with outdated Internet Explorer installations face significant risk as this vulnerability has been widely exploited in the wild, particularly targeting enterprise environments where legacy browser support remains necessary for compatibility reasons.
Mitigation strategies for CVE-2011-2000 should prioritize immediate patching of affected Internet Explorer versions through Microsoft's security updates, as the vendor released specific patches addressing this memory corruption flaw. System administrators should implement browser hardening measures including disabling unnecessary browser features, implementing strict content security policies, and deploying web application firewalls to filter malicious content. Organizations should also consider implementing browser isolation techniques and mandatory security updates to prevent exploitation attempts. The vulnerability underscores the importance of maintaining up-to-date browser software and implementing comprehensive security monitoring to detect potential exploitation attempts. Additionally, user education about avoiding suspicious websites and email attachments remains crucial in preventing successful exploitation of this memory corruption vulnerability.