CVE-2019-15348 in Camon
Summary
by MITRE
The Tecno Camon Android device with a build fingerprint of TECNO/H612/TECNO-ID5a:8.1.0/O11019/F-180828V106:user/release-keys contains a pre-installed platform app with a package name of com.lovelyfont.defcontainer (versionCode=7, versionName=7.0.11). This app contains an exported service named com.lovelyfont.manager.FontCoverService that allows any app co-located on the device to supply arbitrary commands via shell script to be executed as the system user that are triggered by writing an attacker-selected message to the logcat log. This app cannot be disabled by the user and the attack can be performed by a zero-permission app. Executing commands as the system user can allow a third-party app to video record the user's screen, factory reset the device, obtain the user's notifications, read the logcat logs, inject events in the Graphical User Interface (GUI), and obtains the user's text messages, and more. Executing commands as the system user can allow a third-party app to factory reset the device, obtain the user's notifications, read the logcat logs, inject events in the GUI, change the default Input Method Editor (IME) (e.g., keyboard) with one contained within the attacking app that contains keylogging functionality, and obtains the user's text messages, and more.
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Analysis
by VulDB Data Team • 11/15/2019
This vulnerability exists within the Tecno Camon Android device firmware where a pre-installed platform application named com.lovelyfont.defcontainer contains an exported service that creates a critical security flaw in the device's permission model. The vulnerable service com.lovelyfont.manager.FontCoverService operates by monitoring logcat logs for specific attacker-selected messages, which then trigger execution of arbitrary shell commands as the system user. This represents a classic privilege escalation vulnerability that bypasses normal Android security boundaries and allows unauthorized code execution with the highest possible privileges available to applications on the device. The vulnerability is particularly concerning because it cannot be disabled by users and requires no special permissions from the attacking application, making it extremely accessible to malicious actors.
The technical implementation of this vulnerability leverages Android's logging system as an attack vector, where the exported service listens for specific log messages that contain shell commands. When such a message is detected in the logcat output, the system executes these commands with system-level privileges, effectively allowing any application on the device to gain root-level access. This flaw aligns with CWE-20: Improper Input Validation and CWE-78: Improper Neutralization of Special Elements used in an OS Command, as the application fails to properly validate or sanitize input from the logging mechanism before executing commands. The attack can be executed through a zero-permission app, which means that standard Android permission models provide no protection against this exploitation, making it particularly dangerous in the context of mobile device security.
The operational impact of this vulnerability is severe and encompasses a comprehensive range of malicious capabilities that can be executed by any third-party application. As the system user, the attacker gains the ability to perform critical device functions including screen recording, factory resetting the device, accessing user notifications, reading logcat logs, injecting GUI events, changing the default input method editor to one containing keylogging functionality, and accessing text messages. This comprehensive access allows for extensive surveillance and data theft capabilities, potentially enabling persistent monitoring of user activities, theft of sensitive communications, and complete control over device functionality. The vulnerability essentially provides a backdoor that allows attackers to maintain persistent access to the device while bypassing all standard Android security controls and user consent mechanisms.
Mitigation strategies for this vulnerability require immediate action from device manufacturers and users. Device manufacturers should implement firmware updates that either disable the vulnerable exported service or properly validate input from logcat before executing commands. Users should avoid installing untrusted applications and consider updating to the latest firmware version if available. From a security perspective, this vulnerability demonstrates the critical importance of proper service exposure controls and input sanitization in Android platform applications. The issue also aligns with ATT&CK technique T1059.004: Command and Scripting Interpreter: PowerShell, where the vulnerability allows for arbitrary command execution through shell scripts, and T1068: Exploitation for Privilege Escalation, which represents the privilege escalation mechanism that allows normal applications to execute with system-level privileges. Organizations should also implement mobile device management solutions that can detect and prevent installation of vulnerable applications while monitoring for suspicious logcat activity patterns that might indicate exploitation attempts.