CVE-2011-1996 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6 through 8 does not properly handle objects in memory, which allows remote attackers to execute arbitrary code by accessing a deleted object, aka "Option Element Remote Code Execution Vulnerability."
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Analysis
by VulDB Data Team • 06/06/2025
Microsoft Internet Explorer versions 6 through 8 contained a critical memory management vulnerability that stemmed from improper handling of objects in memory during the rendering process. This flaw specifically affected how the browser managed memory allocation and deallocation for html elements, particularly option elements within select dropdown menus. The vulnerability arose when the browser allocated memory for an option element but failed to properly invalidate or clear the memory reference when the element was removed from the document. This memory management deficiency created a scenario where attackers could craft malicious web pages that would cause the browser to access freed memory locations, leading to potential code execution.
The technical nature of this vulnerability aligns with CWE-416, which describes the use of freed memory condition, and represents a classic heap-based buffer overflow scenario. When Internet Explorer processed html content containing specially crafted option elements, the browser would maintain references to memory locations that had already been freed, creating a condition where arbitrary code could be executed in the context of the user's session. Attackers exploited this by creating malicious web pages that would trigger the memory access violation when users viewed the page, allowing for remote code execution without requiring any user interaction beyond visiting the compromised website.
The operational impact of this vulnerability was severe as it affected a broad user base since Internet Explorer 6 through 8 were widely deployed across enterprise and consumer environments. The vulnerability could be exploited through web-based attacks without requiring any special privileges or user interaction beyond visiting a malicious website. This made it particularly dangerous for organizations that relied heavily on older versions of Internet Explorer, as the attack surface was extensive and the exploitation was relatively straightforward for skilled attackers. The vulnerability was particularly concerning because it allowed for complete system compromise, potentially enabling attackers to install malware, steal sensitive data, or establish persistent access to affected systems.
The mitigation strategies for this vulnerability included immediate patching through Microsoft's security updates, which addressed the underlying memory management issues in the browser's rendering engine. Organizations should have implemented browser hardening measures, including disabling unnecessary browser features and implementing security policies that restricted access to potentially malicious websites. The ATT&CK framework categorizes this vulnerability under technique T1203, which involves exploiting web browsers for code execution, and T1059, which covers command and scripting interpreters. Additionally, network-based security controls such as web application firewalls and content filtering systems could have helped detect and block malicious payloads attempting to exploit this vulnerability. Organizations should have also considered implementing browser isolation techniques and maintaining up-to-date security patches across all systems to prevent exploitation of this and similar memory corruption vulnerabilities.