CVE-2016-9069 in Firefox
Summary
by MITRE
A use-after-free in nsINode::ReplaceOrInsertBefore during DOM operations resulting in potentially exploitable crashes. This vulnerability affects Firefox < 50.
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Analysis
by VulDB Data Team • 05/30/2023
The vulnerability identified as CVE-2016-9069 represents a critical use-after-free condition within the Mozilla Firefox browser's Document Object Model implementation. This flaw exists in the nsINode::ReplaceOrInsertBefore method which handles DOM node manipulation operations. The vulnerability arises when the browser processes certain DOM operations that involve replacing or inserting nodes within the document structure, creating a scenario where memory previously allocated to a DOM node is accessed after it has been freed by the application's memory management system. Such conditions are particularly dangerous as they can lead to arbitrary code execution when an attacker successfully manipulates the memory layout to achieve controlled exploitation.
The technical nature of this vulnerability places it squarely within the realm of memory safety issues, specifically categorized under CWE-416 as use-after-free conditions. The flaw manifests during DOM operations where the ReplaceOrInsertBefore functionality fails to properly manage reference counts or object lifecycles, allowing a freed memory block to be accessed by subsequent operations. This particular implementation flaw affects Firefox versions prior to 50, indicating that the issue was present in the browser's rendering engine's DOM handling mechanisms for several years. The vulnerability can be triggered through crafted web content that manipulates DOM nodes in specific sequences, making it particularly concerning for web-based attack scenarios.
The operational impact of CVE-2016-9069 extends beyond simple browser instability, as it creates a potential pathway for remote code execution. When exploited, the use-after-free condition can allow attackers to execute arbitrary code with the privileges of the victim's browser process, potentially leading to full system compromise. The vulnerability is particularly dangerous in the context of modern browser exploitation techniques as it can be leveraged through drive-by downloads or malicious websites without requiring user interaction beyond visiting the compromised page. This aligns with ATT&CK technique T1059.007 for Windows Command Shell and similar approaches that leverage browser-based exploitation vectors. The impact is amplified by the widespread adoption of Firefox and the ease with which such vulnerabilities can be weaponized through automated exploitation frameworks.
Mitigation strategies for CVE-2016-9069 primarily focus on immediate patching and browser updates, as Firefox version 50 and later included fixes for this memory management issue. Organizations should prioritize updating all Firefox installations to version 50 or higher to eliminate the risk of exploitation. Additionally, implementing web application firewalls and content filtering solutions can provide additional layers of protection by blocking malicious content before it reaches vulnerable browser instances. Security teams should also consider deploying sandboxing mechanisms and privilege separation techniques to limit the potential damage from successful exploitation attempts. Browser hardening configurations, including disabling unnecessary JavaScript features and implementing strict content security policies, can further reduce the attack surface. The vulnerability serves as a reminder of the critical importance of regular security updates and proper memory management practices in web browser implementations, particularly given the complex nature of DOM manipulation in modern web applications.