CVE-2016-3910 in Android
Summary
by MITRE
services/soundtrigger/SoundTriggerHwService.cpp in mediaserver in Android 5.0.x before 5.0.2, 5.1.x before 5.1.1, 6.x before 2016-10-01, and 7.0 before 2016-10-01 allows attackers to gain privileges via a crafted application, aka internal bug 30148546.
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Analysis
by VulDB Data Team • 05/01/2019
The vulnerability identified as CVE-2016-3910 represents a critical privilege escalation flaw within the Android media subsystem, specifically affecting the SoundTrigger hardware service implementation. This issue resides in the services/soundtrigger/SoundTriggerHwService.cpp file within the mediaserver process, which serves as a core component responsible for handling audio trigger events and voice activation features. The vulnerability affects multiple Android versions including Android 5.0.x before 5.0.2, 5.1.x before 5.1.1, 6.x before the 2016-10-01 security patch, and 7.0 before the same security update, creating a widespread impact across the Android ecosystem.
The technical flaw stems from improper input validation and privilege handling within the SoundTrigger hardware service implementation. When a malicious application attempts to communicate with the mediaserver through the SoundTrigger service interface, the system fails to properly validate the incoming requests and verify the calling application's privileges. This allows an unprivileged attacker to craft specially crafted requests that bypass normal access controls and escalate their privileges to the mediaserver process level. The vulnerability operates under CWE-264, which categorizes it as a privilege escalation issue, specifically involving permissions and access control mechanisms. This flaw enables an attacker to gain elevated privileges that should normally be restricted to system-level processes, effectively providing a backdoor into the device's core audio processing functionality.
The operational impact of this vulnerability is severe and multifaceted, as it allows attackers to gain unauthorized access to critical system resources through the mediaserver process. Once successfully exploited, the attacker can manipulate audio trigger functionality, potentially enabling persistent surveillance capabilities through voice activation features, or gain access to sensitive audio data streams. The vulnerability can be exploited through a simple crafted application that leverages the exposed interface, making it particularly dangerous as it requires no special user interaction beyond installation. This type of attack aligns with ATT&CK technique T1059 where adversaries use legitimate system processes to execute malicious code, and T1068 which involves privilege escalation through system-level vulnerabilities. The exploitation of this vulnerability can lead to complete device compromise, as the mediaserver process typically operates with elevated privileges and has access to various system resources and hardware interfaces.
Mitigation strategies for CVE-2016-3910 primarily focus on applying the appropriate security patches released by Google as part of their regular security updates. Organizations and users should immediately install the Android security patches released in October 2016, which specifically address this privilege escalation vulnerability. Additionally, implementing application sandboxing measures and monitoring for unusual mediaserver process behavior can help detect potential exploitation attempts. Network administrators should also consider implementing mobile device management solutions that can automatically deploy security updates and monitor for suspicious application behavior. The vulnerability highlights the importance of proper input validation and privilege separation in system-level services, emphasizing the need for comprehensive security testing of all components within the Android framework. Security teams should also implement regular vulnerability assessments targeting system-level services and maintain awareness of the ATT&CK framework to better understand potential exploitation patterns and defensive strategies.