CVE-2011-0094 in Internet Explorer
Summary
by MITRE
Use-after-free vulnerability in Microsoft Internet Explorer 6 and 7 allows remote attackers to execute arbitrary code by accessing an object that (1) was not properly initialized or (2) is deleted, aka "Layouts Handling Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 01/06/2025
The vulnerability identified as CVE-2011-0094 represents a critical use-after-free flaw in Microsoft Internet Explorer versions 6 and 7 that fundamentally compromises memory management integrity. This issue arises from improper handling of object lifecycle management within the browser's rendering engine, specifically affecting the layout system that processes web page structures. The vulnerability stems from a classic memory corruption pattern where an object reference persists in memory after the object has been deallocated, creating a scenario where subsequent memory operations can corrupt or overwrite the freed memory space. The flaw manifests when Internet Explorer processes web content that triggers specific layout computations, leading to scenarios where uninitialized or deleted objects remain accessible to malicious code execution. This vulnerability directly maps to CWE-416, which catalogs use-after-free conditions as a primary class of memory safety issues, and aligns with ATT&CK technique T1059.001 for remote code execution through browser exploitation.
The technical exploitation of this vulnerability occurs when a malicious web page triggers a sequence of layout operations that result in an object being freed from memory while still being referenced or accessed by subsequent code paths. In Internet Explorer 6 and 7, the browser's layout engine maintains object references in a manner that fails to properly track object lifecycle states, particularly when handling dynamic content modifications. When an object is deleted but not properly dereferenced, the memory space can be reallocated and overwritten, but the original object references remain valid. Attackers can manipulate web content to force the browser into a state where freed memory is accessed, potentially allowing code execution through memory corruption techniques. The vulnerability specifically impacts the browser's handling of HTML layout computations where objects are managed through reference counting mechanisms that fail to prevent access to deallocated memory regions, creating a window of opportunity for attackers to inject malicious code into the browser process memory space.
The operational impact of CVE-2011-0094 extends beyond simple code execution to encompass complete system compromise capabilities, particularly given the widespread adoption of Internet Explorer 6 and 7 during the affected period. Attackers leveraging this vulnerability can execute arbitrary code with the privileges of the user running the browser, potentially leading to full system compromise through privilege escalation or lateral movement within network environments. The vulnerability's exploitation requires only a malicious web page delivered through standard web browsing channels, making it particularly dangerous for enterprise environments where users may encounter compromised content. The attack surface is broad as the flaw affects fundamental browser rendering operations that occur during normal web page loading and interaction, meaning that users can be compromised simply by visiting malicious websites or opening infected email attachments containing web content. This vulnerability demonstrates the critical importance of browser security in enterprise environments, as the compromised browser process can be leveraged to access sensitive data, establish persistent backdoors, or serve as a launch point for broader network attacks.
Mitigation strategies for CVE-2011-0094 require a multi-layered approach combining immediate patching, browser hardening, and network-level protections. Microsoft issued security updates that addressed the memory management issues in Internet Explorer 6 and 7, specifically targeting the layout engine's object lifecycle management. Organizations should prioritize immediate deployment of security patches and updates, as this vulnerability was actively exploited in the wild during its disclosure period. Browser hardening techniques include implementing security features such as address space layout randomization, data execution prevention, and enhanced memory protection mechanisms that can detect and prevent exploitation attempts. Network-level protections such as web application firewalls, content filtering systems, and browser isolation technologies can provide additional defense layers against exploitation attempts. Additionally, user education and awareness programs should emphasize the dangers of visiting untrusted websites and opening suspicious email attachments. The vulnerability highlights the importance of maintaining up-to-date browser software and implementing comprehensive security policies that include regular security assessments and vulnerability management procedures to prevent similar issues from compromising enterprise security postures.