NetExec/nxc/protocols/ssh.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import logging

from io import StringIO

import paramiko

from nxc.config import process_secret
from nxc.connection import *
from nxc.logger import NXCAdapter
from paramiko.ssh_exception import (
    AuthenticationException,
    NoValidConnectionsError,
    SSHException,
)


class ssh(connection):
    def __init__(self, args, db, host):
        self.protocol = "SSH"
        self.remote_version = None
        self.server_os = None
        super().__init__(args, db, host)

    def proto_logger(self):
        self.logger = NXCAdapter(
            extra={
                "protocol": "SSH",
                "host": self.host,
                "port": self.args.port,
                "hostname": self.hostname,
            }
        )
        logging.getLogger("paramiko").setLevel(logging.WARNING)

    def print_host_info(self):
        self.logger.display(self.remote_version)
        return True

    def enum_host_info(self):
        self.remote_version = self.conn._transport.remote_version
        self.logger.debug(f"Remote version: {self.remote_version}")
        self.server_os = ""
        if self.args.remote_enum:
            stdin, stdout, stderr = self.conn.exec_command("uname -r")
            self.server_os = stdout.read().decode("utf-8")
            self.logger.debug(f"OS retrieved: {self.server_os}")
        self.db.add_host(self.host, self.args.port, self.remote_version, os=self.server_os)

    def create_conn_obj(self):
        self.conn = paramiko.SSHClient()
        self.conn.set_missing_host_key_policy(paramiko.AutoAddPolicy())

        try:
            self.conn.connect(self.host, port=self.args.port)
        except AuthenticationException:
            return True
        except SSHException:
            return True
        except NoValidConnectionsError:
            return False
        except socket.error:
            return False

    def client_close(self):
        self.conn.close()

    def check_if_admin(self):
        # we could add in another method to check by piping in the password to sudo
        # but that might be too much of an opsec concern - maybe add in a flag to do more checks?
        stdin, stdout, stderr = self.conn.exec_command("id")
        if stdout.read().decode("utf-8").find("uid=0(root)") != -1:
            self.logger.info(f"Determined user is root via `id` command")
            self.admin_privs = True
            return True
        stdin, stdout, stderr = self.conn.exec_command("sudo -ln | grep 'NOPASSWD: ALL'")
        if stdout.read().decode("utf-8").find("NOPASSWD: ALL") != -1:
            self.logger.info(f"Determined user is root via `sudo -ln` command")
            self.admin_privs = True
            return True

    def plaintext_login(self, username, password, private_key=None):
        try:
            if self.args.key_file or private_key:
                if private_key:
                    pkey = paramiko.RSAKey.from_private_key(StringIO(private_key))
                else:
                    pkey = paramiko.RSAKey.from_private_key_file(self.args.key_file)

                self.logger.debug(f"Logging in with key")
                self.conn.connect(
                    self.host,
                    port=self.args.port,
                    username=username,
                    passphrase=password if password != "" else None,
                    pkey=pkey,
                    look_for_keys=False,
                    allow_agent=False,
                )
                if private_key:
                    cred_id = self.db.add_credential(
                        "key",
                        username,
                        password if password != "" else "",
                        key=private_key,
                    )
                else:
                    with open(self.args.key_file, "r") as f:
                        key_data = f.read()
                    cred_id = self.db.add_credential(
                        "key",
                        username,
                        password if password != "" else "",
                        key=key_data,
                    )
            else:
                self.logger.debug(f"Logging in with password")
                self.conn.connect(
                    self.host,
                    port=self.args.port,
                    username=username,
                    password=password,
                    look_for_keys=False,
                    allow_agent=False,
                )
                cred_id = self.db.add_credential("plaintext", username, password)

            shell_access = False
            host_id = self.db.get_hosts(self.host)[0].id

            if self.check_if_admin():
                shell_access = True
                self.logger.debug(f"User {username} logged in successfully and is root!")
                if self.args.key_file:
                    self.db.add_admin_user("key", username, password, host_id=host_id, cred_id=cred_id)
                else:
                    self.db.add_admin_user(
                        "plaintext",
                        username,
                        password,
                        host_id=host_id,
                        cred_id=cred_id,
                    )
            else:
                stdin, stdout, stderr = self.conn.exec_command("id")
                output = stdout.read().decode("utf-8")
                if not output:
                    self.logger.debug(f"User cannot get a shell")
                    shell_access = False
                else:
                    shell_access = True

            self.db.add_loggedin_relation(cred_id, host_id, shell=shell_access)

            if self.args.key_file:
                password = f"{password} (keyfile: {self.args.key_file})"

            display_shell_access = f" - shell access!" if shell_access else ""

            self.logger.success(f"{username}:{process_secret(password)} {self.mark_pwned()}{highlight(display_shell_access)}")
            return True
        except (
            AuthenticationException,
            NoValidConnectionsError,
            ConnectionResetError,
        ) as e:
            self.logger.fail(f"{username}:{process_secret(password)} {e}")
            self.client_close()
            return False
        except Exception as e:
            self.logger.exception(e)
            self.client_close()
            return False

    def execute(self, payload=None, output=False):
        try:
            command = payload if payload is not None else self.args.execute
            stdin, stdout, stderr = self.conn.exec_command(command)
        except AttributeError:
            return ""
        if output:
            self.logger.success("Executed command")
            for line in stdout:
                self.logger.highlight(line.strip())
            return stdout