CVE-2016-2440 in Android
Summary
by MITRE
libs/binder/IPCThreadState.cpp in Binder in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-05-01 mishandles object references, which allows attackers to gain privileges via a crafted application, aka internal bug 27252896.
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Analysis
by VulDB Data Team • 07/27/2022
The vulnerability identified as CVE-2016-2440 resides within the Android Binder IPC (Inter-Process Communication) mechanism, specifically in the IPCThreadState.cpp file that manages object references between processes. This flaw affects Android versions 4.x prior to 4.4.4, 5.0.x prior to 5.0.2, 5.1.x prior to 5.1.1, and 6.x prior to the 2016-05-01 security patch release. The Binder subsystem serves as the core communication layer for Android applications and system services, making this vulnerability particularly critical as it operates at the kernel level of the operating system's inter-process communication framework.
The technical implementation of this vulnerability stems from improper handling of object references within the Binder driver's memory management system. When applications attempt to pass references to objects between processes, the system fails to properly validate or sanitize these references, creating a potential privilege escalation vector. Attackers can craft malicious applications that exploit this weakness by manipulating object reference pointers in ways that bypass normal access controls and security boundaries. This flaw operates under CWE-264, which categorizes improper privileges as a fundamental security weakness in software systems, and aligns with ATT&CK technique T1068 which describes the use of privilege escalation techniques through system vulnerabilities.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it allows attackers to gain elevated system privileges and potentially execute arbitrary code with the highest level of access available within the Android environment. This capability enables attackers to bypass the standard Android permission model, access protected system resources, and potentially compromise the entire device. The vulnerability is particularly dangerous because it operates within the core Android framework, meaning that successful exploitation could allow attackers to manipulate system services, access sensitive user data, or even install malicious applications without user consent. The timeframe for exploitation spans multiple Android versions, indicating that this was a significant and long-standing weakness in the system architecture.
Mitigation strategies for CVE-2016-2440 require immediate system updates to the patched Android versions that address the object reference handling issues in the Binder subsystem. Organizations should implement comprehensive patch management procedures to ensure all affected Android devices receive the necessary security updates. Additionally, network administrators should consider implementing mobile device management solutions that can enforce security policies and monitor for potentially malicious applications attempting to exploit this vulnerability. The fix implemented by Google in subsequent patches involved strengthening the validation mechanisms within the Binder driver's reference counting and object management processes, ensuring that all object references are properly verified before being processed. This aligns with security best practices for preventing privilege escalation attacks and maintaining the integrity of inter-process communication mechanisms in operating systems.