CVE-2016-8438 in Android
Summary
by MITRE
Integer overflow leading to a TOCTOU condition in hypervisor PIL. An integer overflow exposes a race condition that may be used to bypass (Peripheral Image Loader) PIL authentication. Product: Android. Versions: Kernel 3.18. Android ID: A-31624565. References: QC-CR#1023638.
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Analysis
by VulDB Data Team • 10/27/2022
The vulnerability identified as CVE-2016-8438 represents a critical security flaw within the Android kernel's Peripheral Image Loader component that operates at the hypervisor level. This issue stems from an integer overflow condition that creates a time-of-check to time-of-use race condition, fundamentally compromising the integrity of the authentication mechanisms designed to protect peripheral device access. The vulnerability specifically affects Android devices running kernel version 3.18, making it particularly concerning given the widespread deployment of this kernel version across various mobile platforms.
The technical implementation of this flaw involves the Peripheral Image Loader's handling of integer values during the authentication process for peripheral devices. When the PIL component processes device images, it fails to properly validate integer boundaries, leading to an overflow condition that can be manipulated by malicious actors. This overflow creates a window where the system's authentication state can be altered between the time a check is performed and when the actual operation occurs, enabling attackers to exploit this temporal gap to bypass authentication requirements. The vulnerability is classified under CWE-190 as an integer overflow condition, which directly maps to the TOCTOU race condition pattern that has been extensively documented in security literature.
The operational impact of this vulnerability extends beyond simple authentication bypass, as it potentially allows unauthorized access to peripheral device functionalities that should be restricted. Attackers could leverage this weakness to inject malicious firmware or manipulate device behavior through unauthorized peripheral connections, creating opportunities for privilege escalation and persistent access to the device's core systems. The hypervisor-level nature of the flaw means that successful exploitation could compromise the fundamental security boundaries that protect Android devices from malicious peripheral interference, aligning with ATT&CK technique T1068 which covers local privilege escalation through kernel vulnerabilities.
Mitigation strategies for CVE-2016-8438 require immediate patching of affected Android kernel versions, with particular attention to the Peripheral Image Loader component's integer validation routines. System administrators should implement firmware update policies that prioritize kernel security patches, especially for devices running kernel 3.18. The fix typically involves correcting the integer overflow handling within the PIL authentication logic to prevent the race condition from occurring. Additionally, organizations should consider implementing monitoring solutions that can detect anomalous peripheral device behavior patterns that might indicate exploitation attempts. Regular security assessments should verify that integer overflow protections are properly implemented across all kernel components, with particular focus on hypervisor-level operations that handle device authentication and access control. The vulnerability demonstrates the critical importance of robust integer validation in security-sensitive code paths and underscores the necessity of thorough code reviews for race condition vulnerabilities in system-level components.