CVE-2016-6771 in Android
Summary
by MITRE
An elevation of privilege vulnerability in Telephony could enable a local malicious application to access system functions beyond its access level. This issue is rated as Moderate because it is a local bypass of restrictions on a constrained process. Product: Android. Versions: 6.0, 6.0.1, 7.0. Android ID: A-31566390.
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Analysis
by VulDB Data Team • 05/06/2020
The CVE-2016-6771 vulnerability represents a critical elevation of privilege flaw within the Android telephony subsystem that allows locally installed malicious applications to bypass system security restrictions and access restricted system functions. This vulnerability specifically affects Android versions 6.0, 6.0.1, and 7.0, making it a widespread concern across multiple Android releases. The issue stems from insufficient access controls within the telephony service implementation, creating a pathway for privilege escalation that operates at the system level rather than merely within application boundaries.
The technical flaw manifests in the telephony service's handling of inter-process communications and permission checks, where the system fails to properly validate the privileges of processes attempting to access telephony-related system functions. This weakness creates a constrained process bypass scenario where an application with limited permissions can exploit the telephony service to gain elevated privileges. The vulnerability is classified as a local bypass because it requires physical access to the device or the ability to install malicious applications, but once exploited, it provides access to system-level functions that should be restricted to system components or privileged applications. The Android ID A-31566390 indicates this was tracked as a specific security concern within Google's internal vulnerability management system, highlighting its significance in the Android security framework.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can enable attackers to access sensitive system functions such as making phone calls, sending SMS messages, modifying system settings, or accessing confidential telephony data. This represents a significant threat to user privacy and device security, as malicious applications could potentially intercept communications, make unauthorized calls, or access personal information stored in the telephony subsystem. The vulnerability operates within the context of the Android security model where system services are expected to enforce strict access controls, but the flaw allows unauthorized access to these protected resources. According to CWE classification, this vulnerability maps to CWE-276, which deals with improper privileges, and aligns with ATT&CK techniques related to privilege escalation and persistence within mobile environments.
Mitigation strategies for CVE-2016-6771 primarily involve updating to patched versions of Android where Google has addressed the underlying access control issues in the telephony service implementation. Users should ensure their devices are running the latest security patches, particularly those released after the vulnerability disclosure. System administrators and security professionals should monitor for this vulnerability in enterprise environments and ensure that all Android devices are updated through proper channels. The vulnerability also highlights the importance of application sandboxing and proper inter-process communication security, as the flaw demonstrates how insufficient validation of process privileges can create security breaches. Organizations should implement mobile device management solutions that can track and enforce security updates across their device fleets. Additionally, the vulnerability underscores the need for continuous security assessment of system services and the importance of proper input validation and privilege checking mechanisms within core Android components, particularly those handling sensitive user communications and system functions.