CVE-2016-2421 in Android
Summary
by MITRE
Setup Wizard in Android 5.1.x before 5.1.1 and 6.x before 2016-04-01 allows physically proximate attackers to bypass the Factory Reset Protection protection mechanism and delete data via unspecified vectors, aka internal bug 26154410.
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Analysis
by VulDB Data Team • 02/03/2019
The vulnerability identified as CVE-2016-2421 represents a critical security flaw in the Android operating system's Setup Wizard component that affected versions 5.1.x prior to 5.1.1 and 6.x prior to the 2016-04-01 security update. This weakness specifically targeted the Factory Reset Protection mechanism, which serves as a fundamental security feature designed to prevent unauthorized access to devices following a factory reset operation. The vulnerability was classified under CWE-284 as an improper access control issue, where the system failed to properly enforce security restrictions during the device setup process.
The technical exploitation of this vulnerability occurred through physical proximity attacks, meaning that an attacker needed to be in close physical contact with the target device to execute the malicious actions. This attack vector aligns with the ATT&CK framework's T1072 technique for "Software Deployment Tools" and T1566 for "Phishing" when considering the broader attack surface. The unspecified vectors mentioned in the description suggest that multiple attack paths existed within the Setup Wizard interface that could be leveraged to bypass the Factory Reset Protection mechanism. These vectors likely involved manipulating the setup wizard's user interface or exploiting timing vulnerabilities in the authentication sequence that normally occurs during device initialization.
The operational impact of this vulnerability was severe as it allowed attackers to completely circumvent the security measures designed to protect user data during factory resets. When a device undergoes a factory reset, the Factory Reset Protection mechanism typically requires the user to authenticate with their Google account credentials before allowing the reset to proceed. This protection prevents malicious actors from simply wiping a device and selling it without removing the previous owner's data. However, CVE-2016-2421 enabled attackers to bypass this protection entirely, potentially allowing them to delete all data on the device or even reinstall the operating system without proper authorization, effectively nullifying one of the most important security features in mobile devices.
Security researchers classified this vulnerability as particularly dangerous due to its accessibility through physical proximity attacks, which can occur in various real-world scenarios such as public transportation, retail environments, or social engineering situations where an attacker gains brief physical access to a device. The vulnerability's impact extends beyond simple data deletion to include potential device compromise and privacy violations. Organizations and individuals using affected Android versions were at risk of losing sensitive information, experiencing identity theft, or having their devices rendered unusable through unauthorized reset operations. The vulnerability also highlighted the importance of timely security updates and the potential risks associated with delayed patch deployment in mobile operating systems.
Mitigation strategies for CVE-2016-2421 focused primarily on updating to patched versions of Android 5.1.1 and 6.0, which contained the necessary security fixes to restore proper Factory Reset Protection functionality. System administrators and security teams recommended immediate deployment of the relevant security patches to all affected devices. Additionally, users were advised to avoid leaving their devices unattended in public places and to ensure they were running the latest security updates from their device manufacturers. The vulnerability underscored the critical importance of maintaining up-to-date security patches and demonstrated how seemingly minor interface flaws in system components could have significant implications for device security and user privacy. Organizations implementing mobile device management policies were encouraged to establish automated update procedures to prevent such vulnerabilities from remaining unpatched on corporate devices.