CVE-2018-14997 in Leagoo
Summary
by MITRE
The Leagoo P1 Android device with a build fingerprint of sp7731c_1h10_32v4_bird:6.0/MRA58K/android.20170629.214736:user/release-keys contains the android framework (i.e., system_server) with a package name of android that has been modified by Leagoo or another entity in the supply chain. The system_server process in the core Android package has an exported broadcast receiver that allows any app co-located on the device to programmatically initiate the taking of a screenshot and have the resulting screenshot be written to external storage. The taking of a screenshot is not transparent to the user; the device has a screen animation as the screenshot is taken and there is a notification indicating that a screenshot occurred. If the attacking app also requests the EXPAND_STATUS_BAR permission, it can wake the device up using certain techniques and expand the status bar to take a screenshot of the user's notifications even if the device has an active screen lock. The notifications may contain sensitive data such as text messages used in two-factor authentication. The system_server process that provides this capability cannot be disabled, as it is part of the Android framework. The notification can be removed by a local Denial of Service (DoS) attack to reboot the device.
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Analysis
by VulDB Data Team • 09/07/2023
The vulnerability described in CVE-2018-14997 represents a critical security flaw in the Leagoo P1 Android device that stems from supply chain modifications to the core Android framework. This issue specifically targets the system_server process within the android package, which has been altered by Leagoo or third parties during the device manufacturing process. The modification introduces an exported broadcast receiver that creates an unintended privilege escalation vector, allowing any application co-located on the device to programmatically trigger screenshot functionality without user consent or awareness. This vulnerability directly violates the principle of least privilege and demonstrates poor security design in the Android framework implementation.
The technical exploitation of this vulnerability occurs through the manipulation of the system_server process, which provides screenshot capabilities that should normally require explicit user interaction and consent. The exported broadcast receiver creates an attack surface that enables malicious applications to take screenshots transparently, bypassing normal user interface protections. The device's screen animation and notification system provide visual indicators that the screenshot was taken, but these mechanisms can be circumvented through additional techniques. The vulnerability becomes particularly dangerous when combined with the EXPAND_STATUS_BAR permission, which allows attackers to wake the device and expand the status bar, thereby capturing sensitive notifications even when the device is locked. This represents a significant bypass of the device's security model and demonstrates how supply chain modifications can introduce dangerous functionality.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass serious security implications for users relying on two-factor authentication and other security-sensitive notifications. The ability to capture notifications containing text messages used for authentication purposes creates a direct pathway for credential theft and account compromise. The fact that this functionality cannot be disabled because it is part of the Android framework core makes the vulnerability particularly concerning, as users have no control over this security feature. Additionally, the vulnerability can be amplified through local denial of service attacks that reboot the device, allowing attackers to repeatedly exploit the screenshot functionality while removing evidence of their activities through notification deletion. This creates a persistent threat that can be maintained across device reboots and system resets.
The vulnerability aligns with several CWE categories including CWE-284 (Improper Access Control) and CWE-310 (Cryptographic Issues) as it allows unauthorized access to sensitive information through improper privilege management. From an ATT&CK framework perspective, this vulnerability maps to T1113 (Screen Capture) and T1056 (Input Capture) with potential for T1531 (Account Access Removal) through notification interception. The supply chain compromise aspect of this vulnerability also relates to T1557 (Adversary-in-the-Middle) and T1558 (Steal or Forge Kerberos Tickets) in scenarios where attackers can leverage the screenshot functionality to gather authentication tokens or other sensitive data. Organizations and users should consider this vulnerability as part of a broader supply chain security assessment, particularly when deploying devices from manufacturers that may modify core Android components without proper security review processes. The recommended mitigation strategy involves avoiding deployment of devices with modified system_server processes and implementing network-based monitoring to detect suspicious screenshot activity patterns, though the fundamental issue cannot be resolved through software patches alone due to its integration within the core framework.