CVE-2017-11023 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, there is a possibility of out-of-bound buffer accesses due to no synchronization in accessing global variables by multiple threads.
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Analysis
by VulDB Data Team • 12/07/2019
The vulnerability identified as CVE-2017-11023 represents a critical concurrency flaw affecting multiple android platforms including MSM variants, Firefox OS for MSM, and QRD Android deployments. This issue stems from insufficient synchronization mechanisms within the linux kernel implementation used by these mobile platforms, creating a scenario where multiple threads can simultaneously access shared global variables without proper coordination. The absence of adequate locking or atomic operations during concurrent access creates a race condition that can lead to unpredictable system behavior and potential security compromises.
The technical flaw manifests as out-of-bound buffer accesses occurring when multiple threads attempt to modify or read global variables concurrently. This type of vulnerability falls under the CWE-362 category of concurrent execution using shared data structures without proper synchronization mechanisms. The root cause lies in the kernel-level implementation where thread safety measures are inadequate, allowing one thread to modify a data structure while another accesses it, potentially resulting in memory corruption, data inconsistency, or arbitrary code execution. The vulnerability specifically affects Android releases from the Code Aurora Forum (CAF) that utilize the linux kernel, making it widespread across numerous mobile device implementations.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can enable attackers to exploit the race condition for privilege escalation or system compromise. When multiple threads access global variables without proper synchronization, the system may experience unpredictable behavior that could be leveraged to execute malicious code or gain elevated privileges. This vulnerability directly relates to ATT&CK technique T1068 which involves the exploitation of system privileges, and T1059 which covers the execution of malicious code through system-level vulnerabilities. The concurrent nature of the flaw means that exploitation could occur through various attack vectors depending on how the affected kernel modules are utilized within the mobile platform.
Mitigation strategies for CVE-2017-11023 require immediate implementation of proper synchronization mechanisms within the affected kernel code. System administrators and device manufacturers should prioritize applying security patches provided by the Code Aurora Forum or respective vendors, as these updates typically include mutex locks, semaphores, or other thread synchronization primitives to protect global variable access. The solution involves implementing proper locking mechanisms around all shared global variables that are accessed by multiple threads, ensuring that only one thread can access the resource at any given time. Additionally, code reviews should be conducted to identify all instances where global variables are accessed concurrently, and developers should implement atomic operations or other synchronization techniques as recommended by the linux kernel development community to prevent similar issues in future implementations.