CVE-2021-1013 in Android
Summary
by MITRE • 12/15/2021
In checkExistsAndEnforceCannotModifyImmutablyRestrictedPermission of PermissionManagerService.java, there is a possible way to determine whether an app is installed, without query permissions, due to side channel information disclosure. This could lead to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12Android ID: A-186404356
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Analysis
by VulDB Data Team • 12/18/2021
This vulnerability exists within the Android permission management system, specifically in the PermissionManagerService.java file where the checkExistsAndEnforceCannotModifyImmutablyRestrictedPermission method fails to properly handle access control checks. The flaw represents a side channel information disclosure vulnerability that allows attackers to determine whether specific applications are installed on a device without requiring explicit permission queries or elevated privileges. The vulnerability stems from the service's inability to properly isolate permission checking operations from information leakage mechanisms, creating a covert channel through which installation status can be inferred. This type of vulnerability aligns with CWE-203, Information Exposure Through Discrepancy, where differences in system behavior reveal sensitive information about the underlying state. The issue occurs at the system level within Android's permission management framework, specifically affecting Android 12 implementations where the PermissionManagerService handles immutable permission restrictions. Attackers can exploit this by observing timing differences or other behavioral discrepancies when attempting to access permission-related information for applications that may or may not be installed, effectively creating a fingerprinting mechanism to determine application presence. The vulnerability does not require user interaction for exploitation, making it particularly concerning as it can be triggered automatically by malicious applications or processes that have basic access to the system. This information disclosure could enable further attacks by providing adversaries with knowledge about installed applications, potentially aiding in targeting specific malware or conducting reconnaissance activities.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can serve as a foundation for more sophisticated attacks within the Android security model. An attacker could leverage this information to craft targeted attacks against specific applications, potentially exploiting known vulnerabilities in particular software packages. The vulnerability's classification under the ATT&CK framework would fall under T1083 (File and Directory Discovery) and potentially T1592 (Resource Hijacking) where the disclosed information could be used to identify and target vulnerable applications. The side channel nature of the vulnerability means that it operates through indirect means rather than direct exploitation, making it harder to detect through traditional security monitoring approaches. The lack of additional execution privileges required for exploitation means that even applications with minimal permissions could potentially utilize this vulnerability to gather intelligence about the device's application landscape. This information could be particularly valuable for attackers planning targeted attacks or for conducting reconnaissance prior to more serious exploitation attempts, as knowledge of installed applications can reveal potential attack vectors and system configurations.
Mitigation strategies for this vulnerability should focus on strengthening the permission checking mechanisms within the Android system and ensuring proper isolation between different information access paths. System-level patches should address the specific implementation flaw in PermissionManagerService.java by ensuring that permission checks do not leak information about application installation status through side channels. The fix should implement proper access control boundaries that prevent information leakage regardless of the access pattern or timing differences that might occur during permission validation. Security teams should consider implementing additional monitoring for unusual permission checking patterns that might indicate exploitation attempts, though the covert nature of the vulnerability makes detection particularly challenging. Device manufacturers and security vendors should prioritize patch deployment for affected Android 12 systems, as the vulnerability affects the core permission management infrastructure. Organizations should also review their application security practices to ensure that applications are not inadvertently creating additional side channels or information leaks that could compound the impact of this vulnerability. The fix should align with security best practices outlined in the OWASP Mobile Security Project, particularly regarding secure permission handling and information flow management. Regular security assessments should be conducted to identify similar side channel vulnerabilities within other system components that might expose similar information disclosure risks.