CVE-2016-6696 in Android
Summary
by MITRE
sound/soc/msm/qdsp6v2/msm-ds2-dap-config.c in a Qualcomm QDSP6v2 driver in Android before 2016-10-05 allows attackers to cause a denial of service or possibly have unspecified other impact via a large negative value for the data length, aka Qualcomm internal bug CR 1041130.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability identified as CVE-2016-6696 resides within the Qualcomm QDSP6v2 driver component of Android systems, specifically in the msm-ds2-dap-config.c file. This driver operates within the sound subsystem of Qualcomm-based devices and handles configuration data for the QDSP6v2 audio processing unit. The flaw manifests when the driver processes audio configuration parameters that contain negative values for data length fields, creating a scenario where the system fails to properly validate input parameters before processing. This represents a classic buffer overflow vulnerability pattern where improper input validation leads to system instability.
The technical implementation of this vulnerability occurs at the kernel level where the QDSP6v2 driver fails to properly sanitize data length parameters during audio configuration processing. When a malicious actor or compromised application supplies a large negative value for data length, the driver's internal processing logic interprets this value incorrectly, leading to unpredictable behavior. The vulnerability specifically affects Android versions prior to October 5, 2016, indicating it was a time-sensitive issue that required immediate patching. According to CWE standards, this maps to CWE-129: Improper Validation of Array Index, as the driver fails to validate that array indices remain within acceptable bounds. The vulnerability creates a condition where the system's memory management routines become corrupted due to improper handling of negative integer values that should never be valid in this context.
The operational impact of CVE-2016-6696 extends beyond simple denial of service to potentially enable more severe security consequences. While the primary effect is a denial of service that can crash the audio subsystem and potentially cause system instability, the vulnerability's potential for unspecified other impacts suggests it could be leveraged for privilege escalation or information disclosure. Attackers could exploit this flaw by crafting malicious audio configurations that trigger the negative value condition, causing the system to crash or behave unpredictably. This vulnerability aligns with ATT&CK technique T1068: Exploitation for Privilege Escalation, as the kernel-level nature of the vulnerability could potentially be exploited to gain elevated privileges. The QDSP6v2 processor's role in audio processing makes this particularly concerning as audio subsystem access is often available to applications, creating a potential attack vector through legitimate audio processing APIs.
Mitigation strategies for CVE-2016-6696 primarily involve applying the security patches released by Qualcomm and Android vendors. The fix typically includes implementing proper input validation in the msm-ds2-dap-config.c file to reject negative values for data length parameters before they can be processed by the driver. System administrators should ensure all Qualcomm-based Android devices receive the October 2016 security updates that address this specific vulnerability. Additional defensive measures include monitoring for unusual audio processing patterns that might indicate exploitation attempts and implementing application sandboxing to limit potential attack surfaces. The vulnerability highlights the importance of proper input validation in kernel drivers and demonstrates how seemingly simple parameter validation flaws can create significant security risks. Organizations should also consider implementing network-based intrusion detection systems to monitor for exploitation attempts targeting similar kernel-level vulnerabilities in embedded systems.