CVE-2016-9067 in Firefox
Summary
by MITRE
Two use-after-free errors during DOM operations resulting in potentially exploitable crashes. This vulnerability affects Firefox < 50.
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Analysis
by VulDB Data Team • 01/31/2018
The vulnerability identified as CVE-2016-9067 represents a critical security flaw in Mozilla Firefox browsers prior to version 50, where two distinct use-after-free conditions occur during Document Object Model manipulation operations. These flaws arise from improper memory management during DOM traversal and modification processes, creating opportunities for malicious actors to execute arbitrary code on vulnerable systems. The vulnerability specifically targets the browser's JavaScript engine and its interaction with DOM elements, making it particularly dangerous in web-based attack scenarios where user input is processed through browser rendering engines.
The technical implementation of this vulnerability stems from the browser's failure to properly validate memory references during DOM operations, particularly when handling dynamic content modifications and element removal processes. When Firefox processes certain JavaScript operations that manipulate DOM elements, the memory allocated to these objects may be freed while still being referenced elsewhere in the code execution path. This creates a use-after-free condition where subsequent operations attempt to access memory that has already been deallocated, potentially allowing attackers to manipulate memory contents or redirect execution flow. The flaw manifests in two separate code paths within the browser's rendering engine, each presenting unique attack vectors for exploitation.
The operational impact of CVE-2016-9067 extends beyond simple browser crashes, as it provides attackers with a pathway for remote code execution on affected systems. When successfully exploited, this vulnerability enables adversaries to execute malicious code with the privileges of the browser process, potentially leading to full system compromise. The vulnerability affects all versions of Firefox prior to 50, making it particularly concerning given the widespread adoption of the browser and the difficulty of maintaining up-to-date software across enterprise environments. Attackers can leverage this flaw through malicious websites or web content that triggers the specific DOM operations causing the memory corruption, making it a significant threat in phishing campaigns and drive-by download scenarios.
Organizations and users affected by this vulnerability should immediately implement mitigation strategies including prompt software updates to Firefox version 50 or later, which contains patches addressing both use-after-free conditions. Security teams should also consider implementing network-based protections such as web application firewalls and content filtering solutions to block access to known malicious domains. The vulnerability aligns with CWE-416, which describes the use of freed memory condition, and represents a classic example of how improper memory management can create persistent security risks. From an ATT&CK framework perspective, this vulnerability maps to techniques involving remote code execution and privilege escalation through browser-based attacks, making it a critical component of modern threat landscape assessments and defensive security planning.
The remediation process requires comprehensive patch management across all affected Firefox installations, with particular attention to enterprise environments where automated deployment mechanisms may need to be configured. System administrators should also implement monitoring solutions to detect potential exploitation attempts and establish incident response procedures for handling suspected attacks. Regular security assessments should include verification of browser versions and patch status to prevent exploitation of this and similar vulnerabilities. Organizations should also consider implementing browser hardening measures such as sandboxing and privilege reduction techniques to limit potential damage from successful exploitation attempts.