Python

For team servers and/or agents written in Python, a simplistic example is included that can be used as a rough template.

Usage

1. Install Python dependencies

python3 -m pip install extism

1. The example below reads the C4 plugin (.wasm file) from the folder with the name c4.wasm

Thorough documentation on the Python Extism SDK package can be found at https://github.com/extism/python-sdk

The full example can be found at https://github.com/scottctaylor12/C4/examples/python/

Examples

import json
import time
from dataclasses import dataclass
from typing import List, Optional, Tuple

import extism

@dataclass
class C4Output:
    success: bool
    status: str
    messages: Optional[List[str]] = None

def load_plugin():
    with open("c4.wasm", "rb") as f:
        wasm_bytes = f.read()
    manifest = {
        "wasm": [{"data": wasm_bytes}],
        "allowed_hosts": ["*"],
    }
    plugin = extism.Plugin(
        manifest,
        wasi=True,
    )
    return plugin

def main():

    # Example usage of the AWS S3 C4 plugin.
    # Implementation details will vary based on your C2 and/or agent

    plugin = load_plugin()

    while True:
        # This agent has an ID of 12345
        # Receive messages from AWS S3 bucket for agent 12345
        rec_msg = json.dumps({
            "action": "receive",
            "params": {
                "agent_id": "12345",
                "access_key": "AKIAXXXXXXXXXXXXX",
                "secret_key": "SECRET",
                "region": "us-east-1",
                "bucket": "c4-testing"
            }
        })

        try:
            out = plugin.call("c4", rec_msg.encode('utf-8'))
            c4_output_dict = json.loads(out.decode('utf-8'))
            c4_output = C4Output(**c4_output_dict)

            if c4_output.success and c4_output.messages and len(c4_output.messages) > 0:
                for message in c4_output.messages:
                    # Process the message as needed
                    print(f"Received message: {message}")

        except Exception as e:
            print(f"Error while receiving message: {e}")

        # Let's pretend we received a "whoami" message
        # Send a response back to the S3 bucket with the "server" as the recipient
        message = "scottctaylor12"  # realistically, the message is probably a format specific to your C2

        send_msg = json.dumps({
            "action": "send",
            "params": {
                "agent_id": "server",
                "message": message,
                "access_key": "AKIAXXXXXXXXXXXXX",
                "secret_key": "SECRET",
                "region": "us-east-1",
                "bucket": "c4-testing"
            }
        })

        try:
            out = plugin.call("c4", send_msg.encode('utf-8'))
            c4_output_dict = json.loads(out.decode('utf-8'))
            c4_output = C4Output(**c4_output_dict)

            if c4_output.success:
                print("Message sent successfully")
            else:
                print(f"Failed to send message: {c4_output.status}")

        except Exception as err:
            print(f"Error during send: {err}")

        time.sleep(5)

if __name__ == "__main__":
    main()