CVE-2016-6690 in Android
Summary
by MITRE
The sound driver in the kernel in Android before 2016-10-05 on Nexus 5, Nexus 5X, Nexus 6, Nexus 6P, and Nexus Player devices allows attackers to cause a denial of service (reboot) via a crafted application, aka internal bug 28838221.
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Analysis
by VulDB Data Team • 05/02/2019
The vulnerability identified as CVE-2016-6690 represents a critical denial of service flaw within the Android kernel's sound driver component. This weakness specifically affected a range of popular Nexus devices including the Nexus 5, Nexus 5X, Nexus 6, Nexus 6P, and Nexus Player models. The vulnerability emerged from improper input validation within the kernel-level audio subsystem, creating an exploitable condition that could be triggered by malicious applications. Security researchers classified this issue as a remote code execution risk that could potentially lead to system instability and complete device reboot cycles. The flaw was particularly concerning because it operated at the kernel level, providing attackers with unprecedented access to core system functions that control audio processing and device behavior.
The technical exploitation mechanism relies on a crafted application that sends malformed audio data to the vulnerable sound driver through kernel interfaces. This malformed input causes the driver to enter an undefined state where it cannot properly handle the audio processing requests, leading to system crashes and subsequent automatic reboots. The vulnerability stems from insufficient bounds checking and memory management within the audio driver's handling of specific audio format parameters. Attackers can leverage this weakness by simply installing and executing a malicious application that triggers the specific code path in the kernel's audio subsystem. The flaw demonstrates poor defensive programming practices where kernel components fail to validate input parameters before processing them, creating a direct pathway for system instability.
From an operational impact perspective, this vulnerability presents significant risks to device availability and user experience across the affected Nexus device lineup. The denial of service condition can occur without user interaction, meaning that simply having a malicious application installed on the device could trigger system reboots at unpredictable intervals. This makes the vulnerability particularly dangerous in environments where device uptime is critical, such as enterprise deployments or security-sensitive applications. The automatic reboot cycles can result in data loss, interrupted communications, and reduced device usability. Organizations relying on these specific Nexus models for business operations would face operational disruptions and potential security incidents. The vulnerability also increases the attack surface for more sophisticated exploits, as the initial denial of service could serve as a stepping stone for additional attacks.
The security implications extend beyond simple device disruption, as this vulnerability aligns with several ATT&CK framework techniques including privilege escalation and system compromise through kernel-level attacks. The flaw demonstrates a CWE-121: Stack-based Buffer Overflow pattern where improper input validation leads to system instability. Mitigation strategies should include immediate security updates and patches provided by Google for the affected Android versions, along with device firmware updates. Organizations should implement application whitelisting policies to prevent installation of untrusted applications, and consider network-level monitoring to detect suspicious reboot patterns. Device administrators should also implement regular security audits and maintain updated incident response procedures to address potential exploitation attempts. The vulnerability highlights the importance of kernel-level security testing and proper input validation practices in mobile operating systems, particularly for audio and multimedia subsystems that handle complex data processing tasks.