CVE-2020-27034 in Android
Summary
by MITRE • 12/15/2020
In createSimSelectNotification of SimSelectNotification.java, there is a possible permission bypass due to an unsafe PendingIntent. This could lead to local information disclosure with User execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11Android ID: A-153556754
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Analysis
by VulDB Data Team • 12/18/2020
The vulnerability identified as CVE-2020-27034 resides within the Android system's SimSelectNotification.java component where the createSimSelectNotification method fails to properly validate PendingIntent objects. This flaw represents a critical security weakness that allows for potential permission bypass attacks through unsafe PendingIntent handling mechanisms. The vulnerability specifically affects Android 11 systems and is tracked under Android ID A-153556754, indicating its severity and the need for immediate attention from device manufacturers and security teams.
The technical flaw manifests in how the system constructs PendingIntent objects for SIM selection notifications, where the application fails to implement proper security checks on the intent flags and permissions associated with these pending objects. This unsafe construction creates an opportunity for malicious actors to manipulate the PendingIntent behavior, potentially allowing unauthorized access to sensitive information that should be restricted to specific permissions. The vulnerability operates at the system level where PendingIntent objects are used to defer execution of actions until a later time, but the lack of proper validation creates a path for privilege escalation.
From an operational perspective, this vulnerability enables local information disclosure attacks that require only user execution privileges to exploit successfully. The absence of user interaction requirements makes this particularly concerning as it can be triggered automatically without any manual intervention from the victim. Attackers can leverage this flaw to gain access to sensitive data that should normally be protected by Android's permission model, potentially including SIM-related information, user data, or other confidential system resources that are typically restricted to authorized applications or system processes.
The impact of this vulnerability aligns with CWE-284 permission issues and can be mapped to ATT&CK techniques involving privilege escalation and information gathering. Security researchers have noted that this flaw demonstrates poor input validation and improper handling of system-level objects that should maintain strict security boundaries. The vulnerability's classification as a permission bypass indicates that it undermines Android's core security model by allowing unauthorized access to resources that should require elevated privileges or specific user consent.
Mitigation strategies for CVE-2020-27034 should focus on implementing proper PendingIntent validation mechanisms that enforce strict permission checks and use appropriate intent flags to prevent unauthorized access. Android security teams should ensure that all PendingIntent objects are constructed with proper security parameters including FLAG_IMMUTABLE or FLAG_MUTABLE flags where appropriate, and that the system validates all intent components before allowing their execution. Device manufacturers should prioritize patching this vulnerability through security updates and implement additional monitoring for suspicious PendingIntent usage patterns. The recommended approach includes applying the latest Android security patches, implementing proper code review processes for PendingIntent handling, and establishing robust permission validation mechanisms that prevent unauthorized access to system resources through potentially compromised notification components.