CVE-2017-15820 in Android
Summary
by MITRE
In all Qualcomm products with Android releases from CAF using the Linux kernel, in a KGSL IOCTL handler, a Use After Free Condition can potentially occur.
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Analysis
by VulDB Data Team • 01/08/2020
The vulnerability identified as CVE-2017-15820 represents a critical use after free condition within the KGSL (Kernel Graphics Subsystem) IOCTL handler of Qualcomm Android products running Linux kernel versions. This flaw exists in the Qualcomm Android Framework (CAF) implementations and affects all Qualcomm chipsets that utilize the Linux kernel for their operating system functionality. The KGSL subsystem is responsible for managing graphics processing units and handling graphics-related operations within the kernel space, making it a critical component for device performance and security.
The technical exploitation of this vulnerability occurs within the KGSL IOCTL (Input Output Control) handler where memory management functions fail to properly validate or manage memory references after objects have been freed. When an IOCTL command is processed by the KGSL subsystem, the kernel code executes operations that can lead to a scenario where a pointer reference is maintained after the memory it points to has been deallocated. This memory corruption condition creates opportunities for attackers to manipulate the system's memory layout and potentially execute arbitrary code with kernel privileges.
The operational impact of this vulnerability extends across all Qualcomm Android devices that utilize the affected kernel versions, including smartphones, tablets, and other mobile devices running Android operating systems. Attackers can leverage this use after free condition to escalate privileges from user-level applications to kernel-level processes, potentially gaining complete system control. The vulnerability is particularly dangerous because it operates within kernel space, bypassing standard user-space security mechanisms and allowing for persistent system compromise.
From a cybersecurity perspective, this vulnerability aligns with CWE-416, which specifically addresses the use of freed memory condition, and represents a classic example of memory safety issues that have plagued kernel-level code for decades. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the kernel execution environment. The vulnerability's exploitation potential makes it a high-value target for advanced persistent threat actors and mobile malware developers seeking to establish persistent backdoors on targeted devices. Organizations should implement immediate mitigations including kernel updates, memory safety checks, and monitoring for anomalous IOCTL activity, while also considering the broader implications for mobile device security and the need for enhanced kernel security measures in embedded systems.
The widespread nature of this vulnerability across Qualcomm's product portfolio means that device manufacturers must ensure comprehensive patching strategies are implemented across all affected models. The vulnerability's presence in the Linux kernel subsystem also highlights the importance of kernel security hardening and the need for continuous security assessments of core operating system components. Security professionals should monitor for indicators of compromise related to unauthorized kernel modifications and implement network-based detection measures to identify potential exploitation attempts.