CVE-2016-3796 in Android
Summary
by MITRE
The MediaTek power driver in Android before 2016-07-05 on Android One devices allows attackers to gain privileges via a crafted application, aka Android internal bug 29008443 and MediaTek internal bug ALPS02677244.
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Analysis
by VulDB Data Team • 02/22/2019
The vulnerability identified as CVE-2016-3796 represents a critical privilege escalation flaw within the MediaTek power driver component of Android operating systems. This vulnerability specifically affected Android One devices and remained unpatched until the 2016-07-05 security update cycle. The flaw resides in the kernel-level power management driver developed by MediaTek, which serves as a crucial interface between the hardware power management units and the Android operating system's power management framework. The vulnerability was classified as a privilege escalation issue because it allowed malicious applications to elevate their execution privileges from standard user-level access to kernel-level privileges, effectively bypassing Android's security model.
The technical implementation of this vulnerability stems from improper input validation and insufficient access controls within the MediaTek power driver's ioctl (input/output control) interface. Attackers could exploit this weakness by crafting a malicious application that would invoke specific ioctl commands designed to manipulate the power management subsystem. The flaw likely involved inadequate parameter checking within the driver's command processing logic, allowing attackers to pass malformed or unauthorized parameters that would trigger unintended behavior within the kernel space. This type of vulnerability typically maps to CWE-121, which describes stack-based buffer overflow conditions, or CWE-122, which covers heap-based buffer overflows, though the specific implementation may vary based on the exact nature of the driver's memory handling.
The operational impact of this vulnerability extends beyond simple privilege escalation, creating a pathway for sophisticated attacks that could compromise entire device security. Once an attacker gains kernel-level privileges through this vulnerability, they can execute arbitrary code with complete system access, potentially enabling them to install persistent backdoors, modify system files, extract sensitive data, or disable security features. The vulnerability's presence on Android One devices, which were designed to provide a clean, stock Android experience, made the attack surface particularly concerning as these devices were often considered more secure than their customized counterparts. This flaw essentially undermined the fundamental security model of Android's kernel-level protection mechanisms, as it allowed attackers to bypass the typical security boundaries that separate user applications from system-level processes.
Mitigation strategies for this vulnerability required immediate patching of the affected Android One devices through the standard security update process. The fix involved implementing proper input validation within the MediaTek power driver's ioctl handling code, ensuring that all parameters passed to the driver were properly checked against expected values and ranges. Organizations and users needed to prioritize the installation of the Android security update released on July 5, 2016, which addressed the specific driver-level flaw. Additionally, security researchers recommended implementing runtime monitoring solutions that could detect anomalous behavior patterns consistent with privilege escalation attempts, particularly focusing on unusual ioctl calls targeting power management interfaces. This vulnerability also highlighted the importance of supply chain security and the need for comprehensive testing of third-party driver components, as it demonstrated how hardware vendor-specific code could introduce critical security weaknesses into otherwise secure operating systems. The ATT&CK framework would categorize this vulnerability under privilege escalation techniques, specifically mapping to T1068, which describes 'Exploitation for Privilege Escalation', and potentially T1059, which covers 'Command and Scripting Interpreter' as attackers might use the elevated privileges to execute additional malicious commands.