NtOpenThreadTokenEx function (ntifs.h)

Article
02/22/2023

The NtOpenThreadTokenEx routine opens the access token associated with a thread.

Syntax

__kernel_entry NTSYSCALLAPI NTSTATUS NtOpenThreadTokenEx(
  [in]  HANDLE      ThreadHandle,
  [in]  ACCESS_MASK DesiredAccess,
  [in]  BOOLEAN     OpenAsSelf,
  [in]  ULONG       HandleAttributes,
  [out] PHANDLE     TokenHandle
);

Parameters

[in] ThreadHandle

Handle to the thread whose access token is to be opened. The handle must have THREAD_QUERY_INFORMATION access. Use the NtCurrentThread macro to specify the current thread.

[in] DesiredAccess

ACCESS_MASK structure specifying the requested types of access to the access token. These requested access types are compared with the token's discretionary access-control list (DACL) to determine which access rights are granted or denied.

[in] OpenAsSelf

Boolean value specifying whether the access check is to be made against the security context of the thread calling NtOpenThreadTokenEx or against the security context of the process for the calling thread.

If this parameter is FALSE, the access check is performed using the security context for the calling thread. If the thread is impersonating a client, this security context can be that of a client process. If this parameter is TRUE, the access check is made using the security context of the process for the calling thread.

[in] HandleAttributes

Attributes for the created handle. Only OBJ_KERNEL_HANDLE is currently supported. If the caller is not running in the system process context, it must specify OBJ_KERNEL_HANDLE for this parameter.

[out] TokenHandle

Pointer to a caller-allocated variable that receives a handle to the newly opened access token.

Return value

NtOpenThreadTokenEx returns STATUS_SUCCESS or an appropriate error status. Possible error status codes include the following:

Return code	Description
STATUS_ACCESS_DENIED
ThreadHandle did not have THREAD_QUERY_INFORMATION access.
STATUS_CANT_OPEN_ANONYMOUS	The client requested the SecurityAnonymous impersonation level. However, an anonymous token cannot be opened. For more information, see SECURITY_IMPERSONATION_LEVEL.
STATUS_INVALID_HANDLE	ThreadHandle was not a valid handle.
STATUS_INVALID_PARAMETER	The specified HandleAttributes did not include OBJ_KERNEL_HANDLE.
STATUS_NO_TOKEN	An attempt has been made to open a token associated with a thread that is not currently impersonating a client.
STATUS_OBJECT_TYPE_MISMATCH	ThreadHandle was not a thread handle.

Remarks

NtOpenThreadTokenEx opens the access token associated with a thread and returns a handle for that token.

The OpenAsSelf parameter allows a server process to open the access token for a client process when the client process has specified the SecurityIdentification impersonation level for the SECURITY_IMPERSONATION_LEVEL enumerated type. Without this parameter, the calling process is not able to open the client's access token using the client's security context because it is impossible to open executive-level objects using the SecurityIdentification impersonation level.

Any handle obtained by calling NtOpenThreadTokenEx must eventually be released by calling NtClose.

Driver routines that run in a process context other than that of the system process must set the OBJ_KERNEL_HANDLE attribute for the HandleAttributes parameter of NtOpenThreadTokenEx. This restricts the use of the handle returned by NtOpenThreadTokenEx to processes running in kernel mode. Otherwise, the handle can be accessed by the process in whose context the driver is running.

For more information about security and access control, see Windows security model for driver developers and the documentation on these topics in the Windows SDK.

For calls from kernel-mode drivers, the NtXxx and ZwXxx versions of a Windows Native System Services routine can behave differently in the way that they handle and interpret input parameters. For more information about the relationship between the NtXxx and ZwXxx versions of a routine, see Using Nt and Zw Versions of the Native System Services Routines.

Requirements

Requirement	Value
Minimum supported client	Windows XP
Target Platform	Universal
Header	ntifs.h (include Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	PASSIVE_LEVEL
DDI compliance rules	HwStorPortProhibitedDDIs, PowerIrpDDis