CVE-2019-9456 in Android
Summary
by MITRE
In the Android kernel in Pixel C USB monitor driver there is a possible OOB write due to a missing bounds check. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 08/13/2020
The vulnerability identified as CVE-2019-9456 resides within the Android kernel implementation specifically affecting the Pixel C USB monitor driver component. This flaw represents a critical security weakness that stems from inadequate input validation mechanisms within the kernel space code responsible for handling USB monitor connections. The vulnerability manifests as a missing bounds check that fails to properly validate the size or range of data being processed during USB communication operations, creating a potential attack vector that could be exploited by malicious actors.
The technical nature of this vulnerability aligns with CWE-129, which describes improper validation of array index or buffer bounds, and CWE-787, which addresses out-of-bounds write conditions. The flaw occurs in the kernel driver context where the USB monitor functionality attempts to write data beyond the allocated memory boundaries without proper validation of the data size or position. This missing bounds check creates an opportunity for attackers to manipulate memory layout and potentially execute arbitrary code with elevated privileges. The vulnerability's classification as a local privilege escalation issue indicates that exploitation requires system execution privileges as a baseline, but does not necessitate user interaction, making it particularly concerning for automated exploitation scenarios.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables potential privilege escalation from a regular user context to system-level execution privileges. Attackers could leverage this flaw to gain complete control over the device's kernel space operations, potentially leading to full system compromise. The absence of user interaction requirements makes this vulnerability particularly dangerous in environments where automatic execution of malicious code might occur, such as in compromised device scenarios or when users unknowingly connect malicious USB peripherals. This vulnerability affects devices running Android versions prior to the security patch release and represents a significant concern for device manufacturers and security administrators who must maintain updated kernel implementations.
Mitigation strategies for CVE-2019-9456 should focus on immediate patch deployment for affected Android versions, with particular emphasis on Pixel C devices and other affected hardware platforms. System administrators should implement comprehensive monitoring for unusual kernel behavior patterns that might indicate exploitation attempts, while also ensuring that USB peripheral access controls are properly configured to limit potential attack surface. The vulnerability demonstrates the critical importance of rigorous bounds checking in kernel space code and highlights the necessity of comprehensive security testing for device drivers, particularly those handling external hardware interfaces. Organizations should also consider implementing additional security controls such as kernel address space layout randomization and other exploit mitigation techniques to reduce the overall risk exposure associated with such kernel-level vulnerabilities.