CVE-2011-1963 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 7 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 "XSLT Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 11/17/2021
The CVE-2011-1963 vulnerability represents a critical memory corruption issue affecting Microsoft Internet Explorer versions 7 through 9, classified under the Common Weakness Enumeration CWE-125 as "Out-of-bounds Read" and CWE-787 as "Out-of-bounds Write." This vulnerability stems from improper handling of objects in memory during XSLT (Extensible Stylesheet Language Transformations) processing, creating a dangerous condition where attackers can manipulate memory access patterns to execute arbitrary code on vulnerable systems. The flaw specifically manifests when Internet Explorer processes XSLT documents that contain malformed or improperly initialized objects, leading to memory corruption that can be exploited through carefully crafted web content.
The technical exploitation of this vulnerability occurs through a classic use-after-free or double-free memory corruption pattern where an attacker can cause the browser to access memory locations that either contain uninitialized data or have already been deallocated. When Internet Explorer processes XSLT transformations, it maintains objects in memory that may not be properly validated or initialized before access, creating opportunities for attackers to inject malicious code into the browser's memory space. This type of vulnerability aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript' and T1203 for "Exploitation for Client Execution" within the adversary tactics and techniques framework.
The operational impact of CVE-2011-1963 is severe as it enables remote code execution without user interaction, making it particularly dangerous for enterprise environments where users may browse untrusted websites or receive malicious emails containing crafted XSLT content. Attackers can leverage this vulnerability to deploy malware, establish persistent backdoors, or escalate privileges within the victim's system, often bypassing standard security controls such as antivirus solutions and firewalls. The vulnerability affects a broad range of Windows operating systems including Windows Vista, Windows 7, and Windows Server 2008, making it a prime target for nation-state actors and organized cybercriminal groups seeking to compromise large user bases.
Mitigation strategies for this vulnerability include applying Microsoft's security patches promptly, implementing browser hardening measures such as disabling XSLT processing for untrusted content, and deploying web application firewalls that can detect and block malicious XSLT content. Organizations should also consider implementing application whitelisting policies to restrict execution of potentially malicious code, along with network segmentation to limit the potential impact of successful exploitation. The vulnerability highlights the importance of proper memory management in browser applications and serves as a reminder of the critical need for regular security updates and comprehensive vulnerability management programs that can address both known and emerging threats in the browser security landscape.