CVE-2011-1256 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 an object that (1) was not properly initialized or (2) is deleted, aka "DOM Modification Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 11/08/2021
The vulnerability identified as CVE-2011-1256 represents a critical memory corruption flaw in Microsoft Internet Explorer versions 6 through 8 that stems from improper handling of objects in memory during dynamic web page execution. This vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read conditions where programs access memory locations beyond the intended boundaries of allocated objects. The flaw manifests when Internet Explorer encounters web content that attempts to manipulate Document Object Model elements in ways that violate expected memory management practices, creating opportunities for malicious code execution through memory corruption attacks.
The technical mechanism behind this vulnerability involves the browser's handling of JavaScript objects and DOM elements that have either not been properly initialized or have been prematurely deleted from memory. When Internet Explorer processes web pages containing malicious JavaScript code, it may attempt to access object references that no longer exist or are in an inconsistent state due to improper memory management. This memory corruption occurs during the execution phase of web page rendering when the browser's JavaScript engine attempts to modify or access DOM objects that have been freed or improperly allocated, creating a scenario where attacker-controlled data can overwrite critical memory locations.
The operational impact of this vulnerability is severe as it enables remote code execution attacks without requiring user interaction beyond visiting a malicious web page. Attackers can craft specially designed web content that, when rendered by the affected Internet Explorer versions, triggers the memory corruption condition and allows arbitrary code execution with the privileges of the user running the browser. This vulnerability particularly affects enterprise environments where older Internet Explorer versions remain in use, as these systems represent significant attack vectors for sophisticated threat actors. The vulnerability's exploitation typically follows the ATT&CK technique T1059.007 for execution through scripting languages, leveraging the browser's JavaScript engine to deliver payload code.
Mitigation strategies for CVE-2011-1256 focus primarily on immediate remediation through Microsoft security updates and patches that address the underlying memory management issues in Internet Explorer. Organizations should prioritize upgrading to supported browser versions or implementing the relevant security patches provided by Microsoft as part of their vulnerability management processes. Additional protective measures include implementing browser security features such as Enhanced Protected Mode in Internet Explorer, configuring security zones with appropriate restrictions, and deploying web application firewalls that can detect and block malicious content targeting this specific vulnerability. The vulnerability also highlights the importance of maintaining current security practices and avoiding the use of deprecated browser versions that lack modern security protections and regular updates.