CVE-2023-21171 in Android
Summary
by MITRE • 06/28/2023
In verifyInputEvent of InputDispatcher.cpp, there is a possible way to conduct click fraud due to side channel information disclosure. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-13Android ID: A-261085213
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Analysis
by VulDB Data Team • 09/13/2025
The vulnerability identified as CVE-2023-21171 resides within the Android operating system's input handling mechanism, specifically in the verifyInputEvent function located in InputDispatcher.cpp. This flaw represents a significant security concern as it enables potential click fraud attacks through side channel information disclosure pathways. The vulnerability operates at the system level where input events are processed and verified, creating an opportunity for malicious actors to exploit timing variations and information leakage patterns that occur during input event processing. The issue manifests when the system fails to properly validate input events, allowing attackers to potentially manipulate or predict input sequences through observation of side channel characteristics.
The technical implementation of this vulnerability stems from insufficient input validation mechanisms within the Android InputDispatcher component, which is responsible for managing and routing input events to appropriate applications. When processing input events, the system's verification process does not adequately account for timing variations and information leakage that could be exploited by attackers. This weakness creates a scenario where an attacker with system execution privileges could leverage temporal side channel information to influence the behavior of input processing. The vulnerability's classification as a local privilege escalation issue indicates that while the attack requires system-level execution capabilities, the ultimate impact allows for elevation of privileges within the system context. The absence of user interaction requirements for exploitation makes this vulnerability particularly concerning as it can be triggered automatically without requiring user participation or deception.
The operational impact of CVE-2023-21171 extends beyond simple click fraud capabilities to represent a fundamental weakness in Android's input processing security model. Attackers who can execute code at the system level can potentially manipulate input events to perform unauthorized actions, potentially leading to complete system compromise. The side channel information disclosure aspect means that timing variations in input processing can reveal sensitive information about the system state or application behavior, which can then be leveraged to craft more sophisticated attacks. This vulnerability directly impacts Android 13 systems and represents a failure in the system's input validation and security boundary enforcement. The vulnerability aligns with CWE-200 (Information Exposure) and CWE-347 (Improper Verification of Cryptographic Signature) categories, as it involves information disclosure through side channels and inadequate validation mechanisms. From an ATT&CK framework perspective, this vulnerability maps to T1068 (Exploitation for Privilege Escalation) and T1550 (Use of Unauthorized Command and Control Channel) where the compromised system can be used for further malicious activities.
Mitigation strategies for CVE-2023-21171 should focus on strengthening input validation mechanisms within the Android InputDispatcher component and implementing additional security controls to prevent side channel information leakage. System administrators and developers should ensure that all input events are properly validated and that timing variations are not exposed through the input processing pipeline. The Android security team has likely addressed this vulnerability through system updates and patches that enhance the verification process in InputDispatcher.cpp. Organizations should implement comprehensive monitoring for unusual input processing patterns and ensure that all Android devices are updated to the latest security patches. Additional protective measures include implementing input sanitization routines and strengthening the security boundaries around system-level input processing components. The vulnerability highlights the importance of side channel attack prevention in operating system security and emphasizes the need for robust input validation mechanisms that cannot be easily bypassed through timing or information leakage attacks.