CVE-2018-9492 in Android
Summary
by MITRE
In checkGrantUriPermissionLocked of ActivityManagerService.java, there is a possible permissions bypass. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android Versions: Android-8.0 Android-8.1 Android-9.0 Android ID: A-111934948
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Analysis
by VulDB Data Team • 03/29/2020
The vulnerability identified as CVE-2018-9492 represents a critical permissions bypass flaw within the Android operating system's ActivityManagerService component. This issue resides in the checkGrantUriPermissionLocked method, which is responsible for managing URI permission grants between applications. The vulnerability affects Android versions 8.0, 8.1, and 9.0, making it a widespread concern across multiple Android releases. The flaw allows for local privilege escalation without requiring any additional execution privileges, meaning that an attacker with basic application-level access could potentially elevate their privileges to system level. This particular vulnerability falls under the CWE-284 access control weakness category, specifically addressing improper access control mechanisms within the Android permission system. The absence of user interaction requirements for exploitation makes this vulnerability particularly dangerous as it can be triggered automatically without any user involvement.
The technical implementation of this vulnerability stems from how the ActivityManagerService handles URI permission checking during application lifecycle management. When applications attempt to access content providers or other system resources through URI permissions, the checkGrantUriPermissionLocked method should enforce proper access controls. However, due to a flaw in this method's logic, it fails to properly validate or enforce permission boundaries, allowing malicious applications to bypass intended restrictions. The vulnerability specifically manifests when the system processes URI permission grants, potentially enabling an attacker to access resources that should be restricted to other applications or system components. This flaw directly impacts Android's core security model by weakening the sandboxing mechanisms that separate application processes from each other and from system resources.
The operational impact of CVE-2018-9492 extends beyond simple privilege escalation, as it fundamentally undermines Android's application isolation principles. An attacker could potentially access sensitive data, manipulate system resources, or even gain root access to the device through this vulnerability. The implications are particularly severe because the flaw operates at the system level within ActivityManagerService, which is a critical component responsible for managing application lifecycle and resource access. This vulnerability could enable attackers to access personal information, intercept communications, or modify system configurations. From an attacker's perspective, the lack of user interaction requirements makes this vulnerability highly attractive for automated exploitation campaigns, potentially allowing for mass deployment of malicious payloads across affected Android devices. The vulnerability's classification under ATT&CK technique T1068, privilege escalation, highlights its potential for enabling further malicious activities once initial access is gained.
Mitigation strategies for CVE-2018-9492 primarily involve applying the official Android security patches released by Google, which address the specific flaw in the checkGrantUriPermissionLocked method. System administrators and device manufacturers should prioritize the deployment of these updates across all affected Android versions, particularly focusing on devices running Android 8.0, 8.1, and 9.0. Additional protective measures include implementing application whitelisting policies, monitoring for unusual permission requests, and maintaining strict application vetting processes. Organizations should also consider network-based monitoring to detect potential exploitation attempts, as the vulnerability may generate abnormal system access patterns. The security community has classified this vulnerability as high severity, and the recommended mitigation approach aligns with standard Android security best practices. Regular security audits and vulnerability assessments should be conducted to ensure that all affected devices remain properly patched and that no other related vulnerabilities exist within the system.