CVE-2011-1261 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 an object that (1) was not properly initialized or (2) is deleted, aka "Selection Object Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 11/08/2021
The vulnerability identified as CVE-2011-1261 represents a critical memory corruption flaw in Microsoft Internet Explorer versions 6 through 9, specifically affecting the handling of objects in memory during web browsing operations. This issue stems from improper memory management practices within the browser's rendering engine, particularly when dealing with selection objects that are either not properly initialized or have been deleted from memory. The vulnerability falls under the category of memory corruption vulnerabilities, which are classified as CWE-125 in the Common Weakness Enumeration catalog and are commonly exploited through techniques such as buffer overflows or use-after-free conditions. The flaw manifests when Internet Explorer attempts to access memory locations that have already been freed or are in an uninitialized state, creating opportunities for malicious code execution.
The technical exploitation of this vulnerability occurs through a carefully crafted web page that triggers the browser to access improperly managed memory objects during selection operations. When Internet Explorer processes user selections within web content, it maintains internal object references that may not be properly validated before access. Attackers can construct malicious web pages that manipulate these selection objects in ways that cause the browser to dereference memory that has either never been properly initialized or has already been released, leading to unpredictable behavior that can be leveraged for code execution. This type of vulnerability is particularly dangerous because it operates at the core level of browser functionality, where user interactions with web content directly translate into memory operations that can be manipulated by remote attackers.
The operational impact of CVE-2011-1261 extends beyond simple code execution, as it provides attackers with a pathway to achieve arbitrary code execution within the security context of the victim's browser environment. This vulnerability can be exploited through various attack vectors including malicious web pages, compromised websites, or phishing campaigns that deliver crafted content designed to trigger the memory corruption condition. The attack surface is significant given that Internet Explorer 6 through 9 were widely deployed across enterprise and consumer environments, making this vulnerability particularly attractive to threat actors seeking to compromise large numbers of systems. The vulnerability aligns with attack techniques documented in the MITRE ATT&CK framework under the 'Exploitation for Code Execution' tactic, specifically targeting the 'Memory Corruption' technique where adversaries manipulate memory structures to execute malicious code.
Mitigation strategies for CVE-2011-1261 require a multi-layered approach that addresses both immediate security concerns and long-term system hardening. Microsoft released security patches through Windows Update that addressed the memory handling issues in affected Internet Explorer versions, and organizations should ensure all systems are updated to the latest security patches. Browser isolation techniques and enhanced security configurations can provide additional protection by limiting the potential impact of exploitation attempts. Network-based security controls such as web application firewalls and content filtering systems can help detect and block malicious content that attempts to exploit this vulnerability. Organizations should also consider implementing browser hardening practices including disabling unnecessary browser features, restricting ActiveX controls, and employing sandboxing technologies to limit the potential damage from successful exploitation attempts. The vulnerability demonstrates the importance of proper memory management in browser security and highlights the need for continuous security testing and patch management processes.