CVE-2017-11063 in Android
Summary
by MITRE
In Android for MSM, Firefox OS for MSM, QRD Android, with all Android releases from CAF using the Linux kernel, as a result of a race condition between two userspace processes that interact with the driver concurrently, a null pointer dereference can potentially occur.
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Analysis
by VulDB Data Team • 01/16/2021
This vulnerability exists within the Linux kernel implementation across multiple Android variants including MSM, Firefox OS, and QRD Android platforms. The issue stems from a race condition that occurs when two user space processes attempt to interact with the same kernel driver simultaneously. This concurrency problem creates a scenario where the kernel driver fails to properly handle the timing of process interactions, leading to a critical null pointer dereference condition. The vulnerability represents a fundamental flaw in kernel driver synchronization mechanisms that govern how multiple processes access shared kernel resources. The race condition manifests when one process attempts to access a data structure that has been freed or not properly initialized by another concurrent process, resulting in the kernel attempting to dereference a null pointer address. This type of vulnerability falls under the CWE-362 category for race conditions and is particularly dangerous because it can lead to system instability, crashes, or potentially allow privilege escalation attacks. The affected platforms include all Android releases from the Code Aurora Forum that utilize the Linux kernel, making this a widespread issue across numerous mobile devices and embedded systems. The vulnerability is classified under the ATT&CK technique T1068 for Exploitation for Privilege Escalation, as the null pointer dereference could potentially be exploited to gain elevated privileges within the kernel space. The operational impact of this vulnerability is significant as it can cause system crashes, device instability, and potentially provide attackers with opportunities to execute malicious code at the kernel level. The race condition specifically affects kernel drivers that manage hardware resources and require proper synchronization between multiple user space processes. When the race condition occurs, the kernel's memory management system attempts to access a null pointer, which typically results in an immediate system crash or panic. This vulnerability demonstrates the critical importance of proper kernel driver development practices and the necessity of implementing robust synchronization mechanisms to prevent concurrent access issues. The exploitation potential increases when attackers can control the timing of process interactions to force the race condition into occurring at critical moments, potentially enabling more sophisticated attack vectors.
The technical implementation of this vulnerability involves kernel drivers that manage hardware interfaces and communicate with multiple user space processes through system calls and device ioctls. When two processes attempt to access the same driver interface simultaneously, the kernel's locking mechanisms fail to prevent the concurrent access properly. This race condition can occur in various driver subsystems including graphics drivers, network interfaces, or storage controllers. The null pointer dereference occurs because the driver's internal data structures are not properly protected against concurrent access, leading to situations where pointers that should contain valid memory addresses become null. The Linux kernel's memory management subsystem is designed to handle such scenarios gracefully, but the race condition creates an environment where the kernel cannot properly validate pointer states before dereferencing them. This vulnerability is particularly concerning because it operates at the kernel level where system stability and security are paramount, and any compromise of kernel integrity can lead to complete system compromise. The exploitation requires a specific sequence of process interactions that can be difficult to reproduce but not impossible for determined attackers. The vulnerability is classified as a kernel-level race condition that can be leveraged to cause denial of service or potentially enable privilege escalation attacks. Security researchers have noted that such race conditions are notoriously difficult to detect through static code analysis and often require dynamic analysis and stress testing to identify the specific timing conditions that trigger the vulnerability. The impact extends beyond simple system crashes to potentially allow attackers to gain unauthorized access to sensitive system resources or execute arbitrary code with kernel privileges. Mitigation strategies typically involve kernel updates that implement proper locking mechanisms and synchronization primitives to prevent the race condition from occurring. The vulnerability also highlights the importance of proper driver certification and testing in embedded systems where multiple processes may need to access the same hardware resources simultaneously. Organizations should implement comprehensive kernel security measures including kernel address space layout randomization and other exploit mitigations to reduce the risk of exploitation. The vulnerability serves as a reminder of the critical need for proper concurrency control in kernel space and the importance of thorough security testing for all kernel components that handle concurrent access scenarios.