CVE-2015-8940 in Android
Summary
by MITRE
Integer overflow in sound/soc/msm/qdsp6v2/q6lsm.c in the Qualcomm components in Android before 2016-08-05 on Nexus 6 devices allows attackers to gain privileges via a crafted application, aka Android internal bug 28813987 and Qualcomm internal bug CR792367.
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Analysis
by VulDB Data Team • 09/12/2022
The vulnerability identified as CVE-2015-8940 represents a critical integer overflow flaw within the Qualcomm audio subsystem components of Android operating systems. This issue specifically affects the q6lsm.c file in the sound/soc/msm/qdsp6v2/ directory, which forms part of the Android kernel's audio processing framework for Qualcomm Snapdragon processors. The vulnerability exists in Android versions prior to the 2016-08-05 security update, with Nexus 6 devices being particularly susceptible due to their reliance on Qualcomm's proprietary audio processing units. The flaw enables attackers to escalate privileges from a standard application level to system-level access through carefully crafted malicious applications that exploit this vulnerability.
The technical implementation of this integer overflow occurs within the Qualcomm audio processing subsystem where the q6lsm.c component handles communication with the Low Power Sound Manager service. When a malicious application submits audio processing requests with specially crafted parameters, the integer overflow in the buffer size calculations or memory allocation routines causes the system to allocate insufficient memory or creates memory corruption conditions. This memory corruption can be leveraged to overwrite critical system structures or execute arbitrary code in kernel space, bypassing normal privilege boundaries. The vulnerability operates at the kernel level where the audio subsystem interacts with hardware-specific components, making it particularly dangerous as it can be exploited without requiring user interaction beyond installing the malicious application.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and data theft capabilities. Attackers who successfully exploit this flaw can gain full system control over affected Nexus 6 devices, enabling them to install persistent backdoors, modify system files, access sensitive user data, and potentially create covert communication channels. The vulnerability's classification as a kernel-level privilege escalation issue aligns with CWE-190, which specifically addresses integer overflow conditions that can lead to memory corruption and arbitrary code execution. This type of vulnerability is particularly concerning in mobile environments where users frequently install third-party applications, creating multiple attack vectors for exploitation.
From an adversary perspective, this vulnerability maps directly to several ATT&CK framework techniques including privilege escalation through kernel exploits and persistence mechanisms. The attack chain typically involves initial compromise through a malicious application, followed by exploitation of the integer overflow to achieve kernel-level privileges, and finally establishing persistent access to the device. The vulnerability's presence in the audio subsystem makes it particularly stealthy as legitimate audio applications may trigger the exploit conditions without raising immediate user suspicion. Security professionals should note that this vulnerability demonstrates the critical importance of secure coding practices in kernel modules and the potential for hardware-specific components to introduce system-wide security risks. Mitigation efforts should focus on applying the relevant Android security patches, implementing application sandboxing measures, and monitoring for unusual audio processing activities that may indicate exploitation attempts.