CVE-2020-0438 in Android
Summary
by MITRE • 11/10/2020
In the AIBinder_Class constructor of ibinder.cpp, there is a possible arbitrary code execution due to uninitialized data. This could lead to local escalation of privilege if a process were using libbinder_ndk in a vulnerable way with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11 Android-10Android ID: A-161812320
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Analysis
by VulDB Data Team • 12/04/2020
The vulnerability identified as CVE-2020-0438 resides within the AIBinder_Class constructor implementation in the ibinder.cpp file, representing a critical security flaw in Android's binder driver subsystem. This issue manifests as a potential arbitrary code execution vector that stems from uninitialized data handling within the native binder interface. The vulnerability specifically affects Android versions 10 and 11, with the Android ID A-161812320 documenting the precise nature of the flaw. The flaw operates at the kernel level within the libbinder_ndk library, which serves as the foundational component for inter-process communication in Android systems.
The technical root cause of this vulnerability lies in the improper initialization of memory structures within the AIBinder_Class constructor, creating a scenario where uninitialized data can be accessed and potentially manipulated by malicious code. When processes utilize libbinder_ndk in a vulnerable configuration, the uninitialized memory regions become susceptible to exploitation, allowing attackers to execute arbitrary code with the privileges of the target process. This particular flaw represents a classic case of uninitialized memory access that can be leveraged for privilege escalation attacks. The vulnerability operates under CWE-457 which specifically addresses the use of uninitialized variables, making it a direct descendant of well-known software security weaknesses that have been documented in the industry for decades.
The operational impact of CVE-2020-0438 extends beyond simple code execution capabilities, as it enables local privilege escalation without requiring any form of user interaction or additional execution privileges. This means that an attacker who has already gained access to a low-privilege process can leverage this vulnerability to elevate their privileges and gain deeper system access. The attack vector does not require user interaction, making it particularly dangerous as it can be exploited automatically by malicious applications or processes that are already running on the device. This characteristic places the vulnerability squarely within the ATT&CK framework's privilege escalation techniques, specifically targeting the T1068 - Exploitation for Privilege Escalation sub-technique.
The implications of this vulnerability are severe for Android device security, as the binder driver serves as a fundamental component for system communication between applications and system services. When exploited successfully, this vulnerability allows attackers to bypass normal security boundaries and potentially gain access to sensitive system resources, user data, or even escalate to root privileges. The fact that the vulnerability exists in libbinder_ndk, which is used by numerous Android applications and system services, means that the attack surface is extensive and affects a wide range of legitimate processes. Security researchers have noted that such vulnerabilities in core system components like binder drivers can provide attackers with persistent access to devices, making them particularly attractive targets for sophisticated threat actors.
Mitigation strategies for CVE-2020-0438 primarily focus on updating Android systems to versions that contain patches addressing the uninitialized memory access issue. Google has released security updates for affected Android versions that properly initialize the memory structures within the AIBinder_Class constructor, eliminating the arbitrary code execution vector. Organizations and users should ensure their devices are running the latest security patches, as these updates contain the necessary fixes to prevent exploitation of this vulnerability. Additionally, system administrators should monitor for any unauthorized applications that might attempt to exploit this vulnerability, particularly those that interact with binder interfaces or system services. The vulnerability highlights the importance of proper memory initialization practices in security-critical code and serves as a reminder of the potential consequences when fundamental system components contain uninitialized memory access patterns.