Features:
- FUD
The client uses simple tools which makes it completely undetectable, the trojan based on netcat mainly pipe TCP paquets to run the server's commands.
- Firewall
Arbitrium doesn't require adding an exception to the firewall, or a port forwarding rule. The server is an API with endpoints that receives tasks for a specific target and others that the trojan periodically request to get the new instructions, the instructions can be a JavaScript file (the Android app is made using Cordova) or a Shell file to run in the terminal/CMD. Once the server receives a task for a device, the former schedule the task then it opens a child process where it waits for the trojan's response by listening to a dedicated ephemeral port. Therefore, the trojan doesn't need to listen to any port.
- Battery optimization / StealthMode
Unlike with Stock Android, customizations like MIUI by Xiaomi, EMUI by Huawei or Samsung's Android Pie ignore the permissions/exceptions given to an app by the user. So if you try to run an Android's trojan in the background, the moment the app start running frequent or heavy (in some cases even lightweight) tasks (ex: sending http requests periodically) it will be killed no matter what permissions the user grants, ths OS completely ignores the current settings, dontkillmyapp.com is an known website dedicated for this particular issue.
The aforementioned issue was quite annoying while working on this project, after awhile I found that building a lightweight binary that keeps running the assigned tasks in the background while the MainActivity stand still just after launching the binary apears to bypass most the restrictions and actually even improve the performance of the App.
MainActivity receives a JS file from the server and uses ThreadPoolExecutor to initiate the binary without hanging for it to exit (More on this StealthMode/BatteryBypass).
- Web interface
There is also a control panel, it's not a requirement but an extension, it's a simple VueJS webapp, a UI you can use to control the targets instead of directely sending requests to the API. The webapp is available here: Arbitrium WebApp