CVE-2011-1266 in Internet Explorer
Summary
by MITRE
The Vector Markup Language (VML) implementation in vgx.dll in 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 "VML Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 01/15/2025
The vulnerability described in CVE-2011-1266 represents a critical memory corruption flaw within Microsoft Internet Explorer's Vector Markup Language implementation. This issue affects Internet Explorer versions 6 through 8 and resides in the vgx.dll system component that handles VML rendering operations. The vulnerability stems from improper memory management practices where objects are accessed after they have either failed to initialize correctly or have been prematurely deleted from memory. This fundamental flaw in the software's memory handling mechanisms creates an exploitable condition that adversaries can leverage to gain unauthorized code execution privileges on affected systems.
The technical nature of this vulnerability aligns with CWE-125, which describes an out-of-bounds read condition that occurs when a program accesses memory beyond the boundaries of a buffer or object. In the context of this VML implementation, attackers can craft malicious web content that triggers the exploitation of uninitialized or already freed memory objects within the vgx.dll module. The flaw manifests when Internet Explorer processes VML elements that contain malformed or specially crafted parameters, leading to memory corruption that can be controlled to redirect program execution flow. This type of vulnerability falls under the broader category of memory safety issues that have been extensively documented in the cybersecurity community and represent one of the most common attack vectors for privilege escalation exploits.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a pathway to establish persistent access to compromised systems. When successfully exploited, the vulnerability enables remote code execution with the privileges of the logged-on user, potentially allowing attackers to install malware, steal sensitive data, or establish command and control channels. The attack surface is particularly concerning given that Internet Explorer 6 through 8 were widely deployed in enterprise environments during the time this vulnerability was prevalent, making organizations vulnerable to targeted attacks. The exploitability of this condition is enhanced by the fact that it can be triggered through web browsing activities without requiring user interaction beyond visiting a malicious website, making it particularly dangerous in phishing campaigns or drive-by download scenarios.
Mitigation strategies for CVE-2011-1266 primarily focus on immediate remediation through Microsoft's security patches and updates, as well as operational security measures to reduce attack surface exposure. Organizations should prioritize applying the relevant security updates released by Microsoft to address the memory corruption issues in vgx.dll. Additionally, implementing browser isolation techniques, network-based security controls, and web application firewalls can provide additional layers of protection. Security teams should also consider disabling VML support in Internet Explorer where possible, as well as implementing strict web content filtering policies to prevent access to potentially malicious websites. The vulnerability demonstrates the importance of secure coding practices and proper memory management, as outlined in the software security guidelines established by organizations such as the Open Web Application Security Project and the National Institute of Standards and Technology, which emphasize the need for comprehensive input validation and memory safety controls in application development processes.