CVE-2016-3876 in Android
Summary
by MITRE
providers/settings/SettingsProvider.java in Android 6.x before 2016-09-01 and 7.0 before 2016-09-01 allows physically proximate attackers to bypass the SAFE_BOOT_DISALLOWED protection mechanism and boot to safe mode via the Android Debug Bridge (adb) tool, aka internal bug 29900345.
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Analysis
by VulDB Data Team • 09/15/2022
The vulnerability described in CVE-2016-3876 represents a critical security flaw in Android operating systems affecting versions 6.x and 7.0 prior to September 1, 2016. This issue resides within the SettingsProvider.java file in the providers/settings directory of the Android framework, specifically targeting the SAFE_BOOT_DISALLOWED protection mechanism that is designed to prevent unauthorized boot into safe mode. The vulnerability exploits a weakness in the Android Debug Bridge (adb) implementation that allows attackers with physical proximity to bypass security controls that should normally prevent booting into safe mode.
The technical flaw manifests through the improper validation of adb commands that could manipulate system boot parameters. When an attacker gains physical access to an Android device and connects via adb, they can issue specific commands that circumvent the intended protection mechanisms. This occurs because the SettingsProvider.java implementation fails to properly authenticate or validate adb commands that attempt to modify safe boot settings, allowing unauthorized execution of boot mode changes that should be restricted to authorized system processes or users with appropriate privileges.
The operational impact of this vulnerability is significant as it enables attackers to bypass a fundamental security protection mechanism designed to prevent unauthorized system access. Safe mode in Android is intended to provide a restricted environment where only essential system services run, preventing malicious software from executing during boot. By allowing physical proximity attackers to bypass this protection, the vulnerability creates an attack vector that could enable malware installation, system modification, or data extraction. The attack requires only physical access to the device and the ability to connect via adb, making it particularly dangerous in environments where devices may be left unattended.
This vulnerability aligns with CWE-284 (Improper Access Control) and represents a specific instance of inadequate privilege validation within the Android system framework. From an attacker perspective, this flaw maps to techniques described in the MITRE ATT&CK framework under the T1059 (Command and Scripting Interpreter) and T1068 (Exploitation for Privilege Escalation) tactics. The vulnerability demonstrates how insufficient input validation and access control mechanisms in system-level components can create persistent security weaknesses. Organizations should implement mitigations including immediate patching of affected Android versions, disabling adb debugging on production devices, and implementing device management policies that restrict physical access to mobile devices. Additionally, system administrators should monitor for unauthorized adb connections and ensure that only trusted users have access to device debugging interfaces.