CVE-2018-14987 in TV Box
Summary
by MITRE
The MXQ TV Box 4.4.2 Android device with a build fingerprint of MBX/m201_N/m201_N:4.4.2/KOT49H/20160106:user/test-keys contains the Android framework with a package name of android (versionCode=19, versionName=4.4.2-20170213) that dynamically registers a broadcast receiver app component named com.android.server.MasterClearReceiver instead of statically registering it in the AndroidManifest.xml file of the core Android package, as done in Android Open Source Project (AOSP) code for Android 4.4.2. The dynamic-registration of the MasterClearReceiver broadcast receiver app component is not protected with the android.permission.MASTER_CLEAR permission during registration, so any app co-located on the device, even those without any permissions, can programmatically initiate a factory reset of the device. A factory reset will remove all user data and apps from the device. This will result in the loss of any data that have not been backed up or synced externally. The capability to perform a factory reset is not directly available to third-party apps (those that the user installs themselves with the exception of enabled Mobile Device Management (MDM) apps), although this capability can be obtained by leveraging an unprotected app component of core Android process.
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Analysis
by VulDB Data Team • 04/24/2020
The vulnerability described in CVE-2018-14987 represents a critical security flaw in the Android framework implementation of specific MXQ TV Box devices running Android 4.4.2. This issue stems from a deviation in the Android Open Source Project (AOSP) codebase where the MasterClearReceiver broadcast receiver component is dynamically registered rather than statically registered in the AndroidManifest.xml file. The dynamic registration approach creates an exploitable gap in the Android security model that fundamentally undermines the device's integrity and user data protection mechanisms. The flaw specifically affects devices with build fingerprint MBX/m201_N/m201_N:4.4.2/KOT49H/20160106:user/test-keys, indicating this is not a universal Android vulnerability but rather a device-specific implementation error that diverges from standard AOSP practices.
The technical execution of this vulnerability relies on the absence of proper permission checks during the dynamic registration of the MasterClearReceiver component. In standard AOSP implementations, the MasterClearReceiver should be statically registered and protected by the android.permission.MASTER_CLEAR permission, which is a system-level permission typically only granted to system applications and privileged components. However, in the affected MXQ devices, this protection mechanism is bypassed, allowing any application co-located on the device to programmatically trigger a factory reset through the dynamic broadcast receiver. This flaw directly violates the principle of least privilege and demonstrates a failure in the Android security framework's component access control mechanisms. The vulnerability operates at the system level and affects the core Android framework, making it particularly dangerous as it can be exploited by any app present on the device without requiring elevated permissions.
The operational impact of this vulnerability is severe and encompasses complete data loss and device compromise. When exploited, the vulnerability allows attackers to perform unauthorized factory resets that wipe all user data, applications, and settings from the device. This includes personal information, photos, documents, and any other data that has not been backed up or synchronized with external services. The implications extend beyond simple data loss to potential privacy violations and loss of device functionality. From an ATT&CK framework perspective, this vulnerability maps to T1490 (Inhibit System Recovery) and T1070 (Indicator Removal on Host), as it enables the attacker to remove system recovery mechanisms and potentially hide their activities. The vulnerability also represents a privilege escalation vector that could allow attackers to bypass normal user access controls and execute system-level operations. This type of flaw particularly affects IoT and embedded devices where users may not expect the level of security controls available on traditional smartphones or tablets.
Mitigation strategies for this vulnerability must address both immediate protection and long-term security improvements. The most effective immediate solution involves updating the device firmware to a version that properly implements the static registration of the MasterClearReceiver component with appropriate permission checks. System administrators and device manufacturers should ensure that all Android components are properly registered and secured according to AOSP standards. This vulnerability highlights the importance of proper Android security implementation and adherence to established security practices. Organizations should also implement application whitelisting to prevent unauthorized apps from being installed on affected devices. Additionally, regular security audits should verify that all system components are properly registered and protected. The vulnerability underscores the critical need for device manufacturers to follow AOSP security guidelines and maintain proper access controls for system-level components. From a compliance perspective, this flaw would likely violate various security standards including those outlined in CWE-284 (Improper Access Control) and could impact regulatory compliance for devices handling sensitive information.