CVE-2016-5263 in Firefox
Summary
by MITRE
The nsDisplayList::HitTest function in Mozilla Firefox before 48.0 and Firefox ESR 45.x before 45.3 mishandles rendering display transformation, which allows remote attackers to execute arbitrary code via a crafted web site that leverages "type confusion."
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Analysis
by VulDB Data Team • 09/09/2022
The vulnerability identified as CVE-2016-5263 represents a critical type confusion flaw within the nsDisplayList::HitTest function of Mozilla Firefox versions prior to 48.0 and Firefox ESR 45.x prior to 45.3. This vulnerability falls under the CWE-843 category of "Access of Resource Using Incompatible Type" and specifically manifests as a type confusion issue that can be exploited to achieve remote code execution. The flaw occurs during the handling of display transformation rendering operations where the browser fails to properly validate type information during object manipulation, creating an opportunity for malicious actors to manipulate memory structures through crafted web content.
The technical exploitation of this vulnerability relies on the browser's improper handling of object type information within the display list rendering system. When Firefox processes web content that triggers the HitTest function, the type confusion occurs during the transformation of display elements, allowing attackers to manipulate object pointers and memory locations. This type confusion enables attackers to control the execution flow of the browser process, potentially leading to arbitrary code execution with the privileges of the browser user. The vulnerability is particularly dangerous because it can be triggered through standard web browsing activities without requiring user interaction beyond visiting a malicious website.
From an operational perspective, this vulnerability presents significant risk to users of affected Firefox versions as it can be exploited through drive-by download scenarios where simply visiting a compromised website is sufficient to trigger the exploit. The attack vector leverages the browser's rendering engine capabilities to manipulate memory structures, making it difficult to detect through traditional network monitoring. The exploit requires careful crafting of web content that can trigger the specific code path involving nsDisplayList::HitTest and display transformation operations, typically involving complex CSS or WebGL elements that force the browser into problematic rendering states.
Security mitigations for CVE-2016-5263 primarily involve upgrading to Firefox version 48.0 or later, or Firefox ESR 45.3 and subsequent releases where the type confusion issue has been addressed through improved type validation and memory management practices. Organizations should implement comprehensive patch management strategies to ensure all affected systems are updated promptly. Browser vendors have implemented additional protections including address space layout randomization, stack canaries, and improved memory safety checks to prevent similar type confusion vulnerabilities from being exploited in the future. The vulnerability also highlights the importance of maintaining secure coding practices and conducting thorough code reviews for rendering engines, particularly those handling complex object transformations and memory management operations. This issue aligns with ATT&CK technique T1059 for command and scripting interpreter and T1203 for Exploitation for Client Execution, demonstrating how type confusion vulnerabilities can be leveraged to achieve persistent access to compromised systems through browser-based attacks.