CVE-2016-1964 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the AtomicBaseIncDec function in Mozilla Firefox before 45.0 and Firefox ESR 38.x before 38.7 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) by leveraging mishandling of XML transformations.
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Analysis
by VulDB Data Team • 07/09/2022
The CVE-2016-1964 vulnerability represents a critical use-after-free flaw within Mozilla Firefox's handling of XML transformations, specifically within the AtomicBaseIncDec function. This vulnerability affects Firefox versions prior to 45.0 and Firefox ESR 38.x versions prior to 38.7, creating a significant security risk for users of these older browser versions. The flaw stems from improper memory management during XML processing operations, where freed memory locations are accessed after being deallocated, leading to potential exploitation by remote attackers.
The technical implementation of this vulnerability involves memory corruption that occurs when Firefox processes XML documents containing specific transformation operations. When the AtomicBaseIncDec function handles certain XML elements, it fails to properly manage reference counts for memory objects, resulting in a situation where memory that has been freed is subsequently accessed. This use-after-free condition creates a heap memory corruption vulnerability that can be leveraged for arbitrary code execution or denial of service attacks. The vulnerability specifically manifests during XML transformations, where the browser's XML parser and processor encounter malformed or specially crafted XML content that triggers the improper memory handling.
From an operational perspective, this vulnerability presents a severe threat to web application security and user safety, as it allows remote attackers to execute arbitrary code on vulnerable systems without requiring user interaction beyond visiting a malicious website. The exploitation potential aligns with attack techniques described in the MITRE ATT&CK framework under the 'Exploitation for Code Execution' tactic, specifically targeting memory corruption vulnerabilities. The flaw can be exploited through web-based attacks where malicious actors craft XML content designed to trigger the vulnerable code path, potentially leading to complete system compromise. Organizations running affected Firefox versions face significant risk exposure, as the vulnerability can be exploited through standard web browsing activities without any special privileges or user interaction.
The remediation approach for CVE-2016-1964 requires immediate upgrading of Firefox installations to versions 45.0 or later for regular releases, and 38.7 or later for ESR versions. This vulnerability directly relates to CWE-416, which describes the use of freed memory condition, and demonstrates the importance of proper memory management in security-critical applications. Security administrators should implement comprehensive patch management procedures to ensure all Firefox installations are updated promptly. Additionally, network administrators can deploy web application firewalls and content filtering solutions to mitigate potential exploitation attempts while awaiting full patch deployment. The vulnerability underscores the necessity of maintaining up-to-date browser software and implementing layered security approaches to protect against memory corruption exploits that can lead to complete system compromise. Organizations should also consider implementing monitoring solutions to detect potential exploitation attempts targeting this specific vulnerability.