CVE-2016-2482 in Android
Summary
by MITRE
The mm-video-v4l2 vdec component in mediaserver 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 2016-06-01 mishandles a buffer count, which allows attackers to gain privileges via a crafted application, as demonstrated by obtaining Signature or SignatureOrSystem access, aka internal bug 27661749.
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Analysis
by VulDB Data Team • 01/18/2019
The vulnerability identified as CVE-2016-2482 resides within the mm-video-v4l2 vdec component of Android's mediaserver process, representing a critical privilege escalation flaw that affects multiple Android versions including 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-06-01. This issue specifically involves improper handling of buffer counts within the video decoding subsystem, creating a pathway for malicious applications to exploit the system and escalate their privileges to the level of Signature or SignatureOrSystem access. The vulnerability stems from inadequate input validation and memory management within the video decoding component that processes multimedia content through the Linux Video4Linux2 framework.
The technical flaw manifests when the mediaserver process handles buffer management for video decoding operations, where the buffer count parameter is not properly validated or constrained. This mismanagement allows an attacker-controlled application to manipulate the buffer count values in a way that triggers memory corruption or arbitrary code execution within the privileged mediaserver context. The vulnerability operates at the kernel level through the v4l2 video decoder interface, leveraging the inherent trust placed in system-level media processing components. The flaw enables attackers to bypass normal Android security boundaries and gain elevated privileges that would normally require system-level signatures or system-level access rights.
The operational impact of this vulnerability is severe as it allows an attacker to achieve privilege escalation from a regular application to system-level access without requiring physical device access or root privileges. Once exploited, the attacker can gain access to system resources, modify or read protected files, install malicious applications with system-level privileges, and potentially access sensitive user data or device functions. The vulnerability is particularly dangerous because it can be exploited through a crafted application that appears legitimate to the Android security model, making detection and prevention challenging. The exploit demonstrates the classic privilege escalation pattern where a component with elevated privileges is manipulated through improper buffer handling.
Mitigation strategies for this vulnerability include applying the relevant security patches provided by Google for the affected Android versions, implementing proper input validation and buffer boundary checks within the mediaserver component, and restricting the ability of applications to directly interact with low-level video decoding interfaces. Organizations should also consider implementing runtime monitoring for suspicious buffer manipulation patterns and applying the principle of least privilege to media processing components. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and maps to ATT&CK technique T1068, which covers privilege escalation through local exploitation. System administrators should prioritize patch management for affected Android devices and consider implementing additional security controls such as SELinux policies to limit the potential impact of such exploits.