CVE-2011-1964 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 "Style Object Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 11/17/2021
The vulnerability identified as CVE-2011-1964 represents a critical memory corruption flaw in Microsoft Internet Explorer versions 6 through 9 that fundamentally compromises the browser's memory management mechanisms. This issue stems from improper handling of objects within the browser's memory space, creating conditions where malicious actors can exploit uninitialized or already deleted memory objects to gain unauthorized code execution privileges. The vulnerability specifically targets the browser's style object handling system, which is responsible for managing CSS properties and rendering elements on web pages. When Internet Explorer encounters malformed or malicious web content, it fails to properly validate object states before accessing them, leading to unpredictable memory behavior that adversaries can leverage for exploitation.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write operations. These weaknesses occur when the browser's memory management subsystem does not adequately verify object initialization status or memory validity before performing operations on style objects. The exploitation process typically involves crafting malicious web content that triggers the browser to access improperly initialized objects or attempt operations on deleted memory segments. This creates a memory corruption scenario where the attacker can manipulate the execution flow of the browser process, potentially leading to complete system compromise. The vulnerability operates at the intersection of memory safety and browser security architecture, demonstrating how improper object lifecycle management can create persistent attack vectors.
From an operational perspective, this vulnerability presents significant risk to organizations relying on older Internet Explorer versions, as it enables remote code execution without requiring user interaction beyond visiting a malicious website. The attack surface is extensive given the widespread adoption of these browser versions across enterprise environments, particularly in legacy systems where browser updates are delayed or restricted. The exploitation typically follows the attack pattern described in the attack technique T1203, where adversaries leverage browser vulnerabilities to establish persistent access to target systems. Organizations may experience unauthorized access to sensitive data, system compromise, and potential lateral movement within network environments, as the vulnerability allows attackers to execute arbitrary code with the privileges of the user running the affected browser.
Effective mitigation strategies must address both immediate remediation and long-term security posture improvements. The primary recommendation involves updating to supported Internet Explorer versions or migrating to modern browser alternatives that have addressed these memory management deficiencies. Organizations should implement browser hardening measures including disabling unnecessary browser features, implementing content security policies, and deploying web application firewalls to filter malicious content. Additionally, security teams should conduct regular vulnerability assessments targeting legacy browser installations and establish monitoring procedures to detect potential exploitation attempts. The remediation approach should follow the principle of least privilege, ensuring that browser processes operate with minimal required permissions. Organizations must also consider implementing network segmentation and endpoint detection and response solutions to identify and contain potential exploitation attempts, as the vulnerability's remote nature makes proactive detection and prevention essential for maintaining security posture.