CVE-2011-3671 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the nsHTMLSelectElement function in nsHTMLSelectElement.cpp in Mozilla Firefox 4.x through 8.0, Thunderbird 5.0 through 8.0, and SeaMonkey before 2.6 allows remote attackers to execute arbitrary code via vectors involving removal of the parent node of an element.
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Analysis
by VulDB Data Team • 04/13/2017
The CVE-2011-3671 vulnerability represents a critical use-after-free condition affecting Mozilla Firefox versions 4.0 through 8.0, Thunderbird versions 5.0 through 8.0, and SeaMonkey versions prior to 2.6. This flaw resides within the nsHTMLSelectElement function in the nsHTMLSelectElement.cpp source file, demonstrating how improper memory management can lead to remote code execution. The vulnerability specifically manifests when an HTML select element undergoes certain manipulation sequences involving parent node removal, creating a scenario where freed memory is accessed after the original object has been destroyed.
The technical mechanism behind this vulnerability involves the browser's HTML parsing and rendering engine failing to properly track references to HTML select elements when their parent nodes are removed from the document structure. When a parent node containing a select element is removed while the select element itself is still referenced elsewhere in the code, the memory allocated for the select element becomes freed but references to it may persist. Attackers can exploit this by crafting malicious HTML content that triggers specific DOM manipulation sequences, causing the browser to access freed memory locations and execute arbitrary code with the privileges of the running browser process. This vulnerability aligns with CWE-416, which describes the use of freed memory condition, and represents a classic example of improper memory management in web browser engines.
The operational impact of CVE-2011-3671 is severe and far-reaching, as it enables remote code execution without requiring user interaction beyond visiting a malicious website. Attackers can leverage this vulnerability to install malware, steal sensitive information, or take complete control of affected systems. The attack surface is extensive given the widespread adoption of affected browser versions, making this vulnerability particularly dangerous in enterprise environments where users may be running outdated software. The vulnerability can be exploited through various attack vectors including web pages with malicious JavaScript, embedded content, or even through compromised websites that serve malicious content to unsuspecting users. The exploitability of this vulnerability is enhanced by the fact that it does not require any user interaction beyond visiting the malicious site, making it particularly dangerous in phishing campaigns or drive-by download scenarios.
Mitigation strategies for CVE-2011-3671 primarily involve immediate software updates and patches from Mozilla to address the underlying memory management issues in the affected browser versions. Organizations should prioritize updating all affected browsers to versions containing the security fixes, as this vulnerability has been fully addressed in subsequent releases. Additional protective measures include implementing web application firewalls, deploying content security policies, and using browser security extensions that can detect and block malicious DOM manipulation patterns. Network administrators should also consider implementing sandboxing techniques and privilege separation to limit the potential damage if exploitation occurs. The vulnerability demonstrates the importance of regular security updates and proper memory management practices in browser development, aligning with ATT&CK technique T1059 for execution through scripting and T1071 for application layer protocol usage. Organizations should also conduct regular vulnerability assessments to identify and remediate similar memory corruption vulnerabilities that may exist in their browser environments, as this class of vulnerability continues to represent a significant threat vector in web-based attacks.