CVE-2016-3938 in Android
Summary
by MITRE
drivers/video/msm/mdss/mdss_mdp_overlay.c in the Qualcomm video driver in Android before 2016-10-05 on Nexus 5X, Nexus 6, Nexus 6P, and Android One devices allows attackers to gain privileges via a crafted application, aka Android internal bug 30019716 and Qualcomm internal bug CR 1049232.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability identified as CVE-2016-3938 represents a critical privilege escalation flaw within the Qualcomm video driver component of Android operating systems. This issue specifically affects devices including the Nexus 5X, Nexus 6, Nexus 6P, and Android One models, with the vulnerability being present in Android versions prior to the 2016-10-05 security patch release. The flaw resides in the mdss_mdp_overlay.c file which forms part of the MSM (Mobile Services Module) video driver subsystem responsible for managing display overlays and graphics processing on Qualcomm Snapdragon processors. This vulnerability was tracked internally by both Android and Qualcomm as bug 30019716 and CR 1049232 respectively, indicating its significance within the vendor's internal tracking systems.
The technical nature of this vulnerability stems from improper input validation and access control mechanisms within the display overlay driver interface. Attackers can exploit this weakness by crafting a malicious application that manipulates the graphics overlay subsystem to escalate privileges from a regular application context to kernel-level privileges. The flaw likely involves insufficient validation of user-space inputs passed to kernel-space driver functions, allowing crafted parameters to bypass intended access controls and execute unauthorized operations within the kernel. This type of vulnerability falls under CWE-122, which describes "Heap-based Buffer Overflow" conditions, though the specific mechanism involves privilege escalation rather than direct memory corruption. The attack vector requires a locally installed application, making it particularly concerning as it does not require network connectivity or physical access to the device.
The operational impact of this vulnerability is severe as it enables attackers to achieve complete system compromise without requiring physical access or specialized attack infrastructure. Once exploited, the malicious application gains kernel-level privileges, allowing full access to device resources including file system manipulation, network interface control, and the ability to install additional malware or modify system components. This privilege escalation capability effectively neutralizes the Android security model's application sandboxing mechanisms, as the compromised application can bypass all user-level security controls. The vulnerability affects devices running Android versions prior to October 2016, making it particularly dangerous for users who have not installed the relevant security patches, and represents a significant risk to device confidentiality, integrity, and availability.
Mitigation strategies for CVE-2016-3938 primarily involve applying the official security patches released by Google and Qualcomm in their respective Android security bulletins. Users should ensure their devices receive the October 2016 security update which addresses this specific vulnerability by implementing proper input validation and access control mechanisms within the display driver subsystem. Additionally, device manufacturers should conduct thorough security reviews of their driver implementations to identify similar privilege escalation vectors. The vulnerability demonstrates the importance of proper kernel security practices and adherence to secure coding guidelines, particularly in critical system components that handle user-space inputs. Organizations should also implement mobile device management policies that ensure timely patch deployment and monitor for unauthorized applications that might exploit such vulnerabilities. This case highlights the necessity of comprehensive security testing for kernel drivers and the potential consequences of insufficient access control validation in system-level components. The vulnerability serves as a reminder of the critical importance of timely patch management and proper privilege separation in mobile operating systems.