CVE-2019-1985 in Android
Summary
by MITRE
In findAvailSpellCheckerLocked of TextServicesManagerService.java, there is a possible way to bypass the warning dialog when selecting an untrusted spell checker due to a permissions bypass. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-7.0 Android-7.1.1 Android-7.1.2 Android-8.0Android ID: A-118694079
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Analysis
by VulDB Data Team • 10/07/2023
The vulnerability identified as CVE-2019-1985 resides within the Android text services framework, specifically in the TextServicesManagerService.java component. This flaw manifests in the findAvailSpellCheckerLocked method where a permissions bypass occurs that allows unauthorized applications to circumvent security warnings when selecting spell checkers. The issue affects multiple Android versions including 7.0, 7.1.1, 7.1.2, and 8.0, indicating a widespread impact across the Android ecosystem. The vulnerability stems from inadequate permission checking mechanisms that should normally prevent untrusted spell checkers from being selected without explicit user confirmation.
The technical implementation of this vulnerability involves a flaw in the access control model where the system fails to properly validate whether an application attempting to register or select a spell checker has the necessary privileges to do so. When an application attempts to set an untrusted spell checker, the system should present a warning dialog to the user for confirmation. However, due to the permission bypass, this warning mechanism can be circumvented, allowing malicious applications to silently install or activate potentially harmful spell checker components. This represents a direct violation of the principle of least privilege and undermines the security boundaries established by the Android permission system.
The operational impact of CVE-2019-1985 extends beyond simple privilege escalation to potentially enable more sophisticated attacks. An attacker with a malicious application could leverage this vulnerability to install persistent spell checker components that could monitor user input or collect sensitive data. The vulnerability does not require user interaction for exploitation, making it particularly dangerous as it can be triggered automatically when the system processes text input. This type of local privilege escalation allows an attacker to gain elevated system privileges that could enable further malicious activities including data exfiltration, system modification, or persistent backdoor installation. The vulnerability aligns with CWE-284 which addresses improper access control and represents a classic case of privilege escalation through inadequate permission validation.
Mitigation strategies for this vulnerability involve implementing proper access control checks within the spell checker selection process and ensuring that all spell checker registration attempts undergo rigorous validation. Android security updates typically address such issues by strengthening permission enforcement mechanisms and adding additional checks to prevent unauthorized spell checker installations. Organizations should ensure their Android devices are updated to the latest security patches that address this vulnerability, as the affected versions have received security fixes. System administrators should also monitor for applications that attempt to modify spell checker settings or register custom spell checkers, as these activities could indicate exploitation attempts. The vulnerability demonstrates the importance of maintaining robust access control mechanisms throughout the Android framework and highlights the need for continuous security auditing of system components that handle user input processing and text services management. This issue represents a significant concern for enterprise environments where Android devices are used for sensitive communications and data processing activities.