CVE-2016-0831 in Android
Summary
by MITRE
The getDeviceIdForPhone function in internal/telephony/PhoneSubInfoController.java in Telephony in Android 5.x before 5.1.1 LMY49H and 6.x before 2016-03-01 does not check for the READ_PHONE_STATE permission, which allows attackers to obtain sensitive information via a crafted application, aka internal bug 25778215.
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Analysis
by VulDB Data Team • 07/10/2022
The vulnerability described in CVE-2016-0831 represents a critical permission bypass flaw within the Android telephony subsystem that affects versions 5.x before 5.1.1 and 6.x before the 2016-03-01 security update. This issue resides in the internal/telephony/PhoneSubInfoController.java file where the getDeviceIdForPhone function fails to properly validate whether the calling application has been granted the necessary READ_PHONE_STATE permission. The flaw allows malicious applications to extract sensitive device identification information without proper authorization, creating a significant security risk for users of affected Android versions. The vulnerability specifically targets the telephony sub-system's information retrieval mechanisms and exploits a fundamental lack of access control validation within the Android framework.
The technical implementation of this vulnerability stems from the absence of permission verification within the getDeviceIdForPhone function, which is designed to retrieve device identification information such as the IMEI number or other unique device identifiers. According to CWE-284, this represents an improper access control vulnerability where the system fails to properly enforce authorization checks. The flaw operates at the application level within the Android operating system's telephony services, where legitimate applications should be required to possess the READ_PHONE_STATE permission before accessing sensitive device information. Without this permission check, any application can invoke the function and obtain device identifiers that are typically protected from unauthorized access. This creates a direct pathway for attackers to gather device-specific information that could be used for various malicious purposes including device tracking, fraud, or targeted attacks against specific devices.
The operational impact of this vulnerability extends beyond simple information disclosure, as device identifiers such as IMEI numbers are critical components in mobile device authentication and tracking systems. Attackers can leverage this vulnerability to collect device-specific information that could be used to track user activities, correlate with other data breaches, or facilitate more sophisticated attacks. The vulnerability aligns with ATT&CK technique T1082, which involves discovering information about the system, specifically device identifiers and telephony information. This information gathering capability enables threat actors to build detailed profiles of targeted users, potentially leading to more effective social engineering attacks, device-specific malware delivery, or coordinated targeting of particular devices. The vulnerability essentially undermines the Android permission model by allowing unauthorized access to sensitive telephony information that should be restricted to system applications and those with explicit user consent.
The mitigation strategy for CVE-2016-0831 requires immediate system updates to the affected Android versions, specifically applying the security patches released in the 2016-03-01 update cycle for Android 6.x and ensuring proper system upgrades to Android 5.1.1 or later versions. Organizations and users should also implement application whitelisting policies to prevent unauthorized applications from accessing telephony services, though this approach is secondary to the core fix. The vulnerability demonstrates the importance of proper access control implementation in system-level services and reinforces the principle that sensitive information should never be exposed without appropriate permission checks. System administrators should also monitor for applications that might attempt to exploit this vulnerability by requesting telephony information without proper authorization, as this could indicate malicious activity. The fix implemented by Google in subsequent updates involved adding proper permission validation to the getDeviceIdForPhone function, ensuring that only applications with the READ_PHONE_STATE permission can access device identification information, thereby restoring the intended security boundaries within the Android telephony framework.