PoC for an SMS-based shell. Send commands and receive responses over SMS from mobile broadband capable computers.

This tool came as an insipiration during a research on eSIM security implications led by Markus Vervier, presented at Offensivecon 2023

Disclaimer

This is not a complete C2 but rather a simple Proof of Concept for executing commands remotely over SMS.

Requirements

For the shell to work you need to devices capable of sending SMS. The victim’s computer should be equiped with WWAN module with either a physical SIM or eSIM deployed.

On the operator’s end, two tools are provided:

• .NET binary which uses an embedded WWAN module
• Python script which uses an external Huaweu MiFi thourgh its API

Of course, you could in theory use any online SMS provider on the operator’s end via their API.

Usage

On the victim simply execute the client-agent.exe binary. If the agent is compiled as a Console Application you should see some verbose messages. If it’s compiled as a Windows Application (best for real engagements), there will be no GUI.

The operator must specify the victim’s phone number as a parameter:

server-console.exe +306912345678

Whereas if you use the python script you must additionally specify the MiFi details:

python3 server-console.py --mifi-ip 192.168.0.1 --mifi-username admin --mifi-password 12345678 --number +306912345678 -v

A demo as presented by Markus at Offensive is shown below. On the left is the operator’s VM with a MiFi attached, whereas on the right window is client agent.