CVE-2012-4782 in Internet Explorer
Summary
by MITRE
Use-after-free vulnerability in Microsoft Internet Explorer 9 and 10 allows remote attackers to execute arbitrary code via a crafted web site that triggers access to a deleted object, aka "CMarkup Use After Free Vulnerability."
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Analysis
by VulDB Data Team • 04/20/2021
The CVE-2012-4782 vulnerability represents a critical use-after-free flaw in Microsoft Internet Explorer versions 9 and 10 that enables remote code execution through malicious web content. This vulnerability resides in the CMarkup component responsible for handling HTML parsing and rendering operations within the browser's architecture. The flaw occurs when Internet Explorer processes specially crafted web pages that contain malformed markup structures, leading to improper memory management during object lifecycle handling. Attackers can exploit this weakness by hosting malicious websites that trigger the vulnerable code path, causing the browser to access memory locations that have already been freed and potentially overwritten by other operations. The vulnerability specifically targets the memory management subsystem where CMarkup objects are created, manipulated, and eventually destroyed during web page rendering processes.
The technical implementation of this use-after-free vulnerability stems from inadequate validation of object references within Internet Explorer's HTML parser. When processing certain combinations of HTML tags and attributes, the browser's rendering engine creates CMarkup objects that are subsequently freed from memory but remain referenced in other parts of the application. This creates a scenario where malicious code can manipulate the freed memory location to redirect execution flow or inject malicious instructions. The vulnerability falls under CWE-416, which specifically addresses use-after-free conditions where a pointer is used after the memory it points to has been freed. The attack vector requires a user to visit a malicious website, making it particularly dangerous in phishing campaigns or compromised legitimate sites. The exploitation process typically involves creating a memory layout that allows the freed object to be reallocated with attacker-controlled data, enabling arbitrary code execution with the privileges of the Internet Explorer process.
The operational impact of CVE-2012-4782 extends beyond simple remote code execution, as it provides attackers with persistent access to compromised systems through browser-based attacks. Successful exploitation can lead to complete system compromise, allowing threat actors to install malware, steal sensitive data, or establish persistent backdoors. The vulnerability affects a significant portion of the browser market during its time, as Internet Explorer 9 and 10 were widely deployed across enterprise and consumer environments. This exploitability has been extensively documented in various threat intelligence reports and has been incorporated into multiple exploit frameworks. The vulnerability's impact is further amplified by its ability to bypass many traditional security controls, as it operates within the trusted browser environment. Security researchers have noted that this vulnerability demonstrates the complexity of memory management in modern web browsers and the challenges of preventing such flaws in large-scale software applications.
Mitigation strategies for CVE-2012-4782 primarily focus on immediate patch deployment and browser security hardening. Microsoft released security updates that addressed the underlying memory management issues in the CMarkup component, requiring users to apply the relevant patches promptly. Organizations should implement browser security policies that restrict access to untrusted websites and employ content filtering solutions to prevent access to known malicious domains. The vulnerability highlights the importance of regular security updates and the need for organizations to maintain comprehensive patch management processes. Security professionals should also consider implementing additional layers of protection such as browser sandboxing, memory protection mechanisms, and intrusion detection systems to monitor for exploitation attempts. The ATT&CK framework categorizes this vulnerability under technique T1203, which involves exploitation of web browsers for remote code execution, emphasizing the need for layered defensive measures. Organizations should also conduct regular security assessments to identify similar memory corruption vulnerabilities in their browser environments and implement security awareness training to reduce the risk of users visiting malicious websites.