Access Token Manipulation

Adversaries may modify access tokens to operate under a different user or system security context to perform actions and bypass access controls. Windows uses access tokens to determine the ownership of a running process. A user can manipulate access tokens to make a running process appear as though it is the child of a different process or belongs to someone other than the user that started the process. When this occurs, the process also takes on the security context associated with the new token.

An adversary can use built-in Windows API functions to copy access tokens from existing processes; this is known as token stealing. These token can then be applied to an existing process (i.e. Token Impersonation/Theft) or used to spawn a new process (i.e. Create Process with Token). An adversary must already be in a privileged user context (i.e. administrator) to steal a token. However, adversaries commonly use token stealing to elevate their security context from the administrator level to the SYSTEM level. An adversary can then use a token to authenticate to a remote system as the account for that token if the account has appropriate permissions on the remote system.[1]

Any standard user can use the runas command, and the Windows API functions, to create impersonation tokens; it does not require access to an administrator account. There are also other mechanisms, such as Active Directory fields, that can be used to modify access tokens.

ID: T1134
Platforms: Windows
Permissions Required: Administrator, User
Effective Permissions: SYSTEM
Defense Bypassed: File system access controls, Heuristic Detection, Host forensic analysis, System access controls, Windows User Account Control
CAPEC ID: CAPEC-633
Contributors: Jared Atkinson, @jaredcatkinson; Robby Winchester, @robwinchester3; Tom Ueltschi @c_APT_ure; Travis Smith, Tripwire
Version: 2.0
Created: 14 December 2017
Last Modified: 17 October 2021
Provided by LAYER 8

Procedure Examples

ID Name Description
S0622 AppleSeed

AppleSeed can gain system level privilege by passing SeDebugPrivilege to the AdjustTokenPrivilege API.[2]

G0108 Blue Mockingbird

Blue Mockingbird has used JuicyPotato to abuse the SeImpersonate token privilege to escalate from web application pool accounts to NT Authority\SYSTEM.[3]

S0625 Cuba

Cuba has used SeDebugPrivilege and AdjustTokenPrivileges to elevate privileges.[4]

S0038 Duqu

Duqu examines running system processes for tokens that have specific system privileges. If it finds one, it will copy the token and store it for later use. Eventually it will start new processes with the stored token attached. It can also steal tokens to acquire administrative privileges.[5]

S0363 Empire

Empire can use PowerSploit's Invoke-TokenManipulation to manipulate access tokens.[6]

G0037 FIN6

FIN6 has used has used Metasploit’s named-pipe impersonation technique to escalate privileges.[7]

S0203 Hydraq

Hydraq creates a backdoor through which remote attackers can adjust token privileges.[8]

S0607 KillDisk

KillDisk has attempted to get the access token of a process by calling OpenProcessToken. If KillDisk gets the access token, then it attempt to modify the token privileges with AdjustTokenPrivileges.[9]

S0576 MegaCortex

MegaCortex can enable SeDebugPrivilege and adjust token privileges.[10]

S0378 PoshC2

PoshC2 can use Invoke-TokenManipulation for manipulating tokens.[11]

S0194 PowerSploit

PowerSploit's Invoke-TokenManipulation Exfiltration module can be used to manipulate tokens.[12][13]

S0446 Ryuk

Ryuk has attempted to adjust its token privileges to have the SeDebugPrivilege.[14]

S0633 Sliver

Sliver has the ability to manipulate user tokens on targeted Windows systems.[15][16]

S0058 SslMM

SslMM contains a feature to manipulate process privileges and tokens.[17]

S0562 SUNSPOT

SUNSPOT modified its security token to grants itself debugging privileges by adding SeDebugPrivilege.[18]

Mitigations

ID Mitigation Description
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. [19] 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.[20]

Administrators should log in as a standard user but run their tools with administrator privileges using the built-in access token manipulation command runas.[21]

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.

Detection

ID Data Source Data Component
DS0026 Active Directory Active Directory Object Modification
DS0017 Command Command Execution
DS0009 Process OS API Execution
Process Creation
Process Metadata
DS0002 User Account User Account Metadata

If an adversary is using a standard command-line shell, analysts can detect token manipulation by auditing command-line activity. Specifically, analysts should look for use of the runas command. Detailed command-line logging is not enabled by default in Windows.[22]

If an adversary is using a payload that calls the Windows token APIs directly, analysts can detect token manipulation only through careful analysis of user network activity, examination of running processes, and correlation with other endpoint and network behavior.

There are many Windows API calls a payload can take advantage of to manipulate access tokens (e.g., LogonUser [23], DuplicateTokenEx[24], and ImpersonateLoggedOnUser[25]). Please see the referenced Windows API pages for more information.

Query systems for process and thread token information and look for inconsistencies such as user owns processes impersonating the local SYSTEM account.[26]

Look for inconsistencies between the various fields that store PPID information, such as the EventHeader ProcessId from data collected via Event Tracing for Windows (ETW), Creator Process ID/Name from Windows event logs, and the ProcessID and ParentProcessID (which are also produced from ETW and other utilities such as Task Manager and Process Explorer). The ETW provided EventHeader ProcessId identifies the actual parent process.

References