Boot or Logon Autostart Execution: Time Providers

Adversaries may abuse time providers to execute DLLs when the system boots. The Windows Time service (W32Time) enables time synchronization across and within domains.[1] W32Time time providers are responsible for retrieving time stamps from hardware/network resources and outputting these values to other network clients.[2]

Time providers are implemented as dynamic-link libraries (DLLs) that are registered in the subkeys of HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\W32Time\TimeProviders\.[2] The time provider manager, directed by the service control manager, loads and starts time providers listed and enabled under this key at system startup and/or whenever parameters are changed.[2]

Adversaries may abuse this architecture to establish persistence, specifically by creating a new arbitrarily named subkey pointing to a malicious DLL in the DllName value. Administrator privileges are required for time provider registration, though execution will run in context of the Local Service account.[3]

ID: T1547.003
Sub-technique of:  T1547
Platforms: Windows
Permissions Required: Administrator, SYSTEM
Contributors: Harun Küßner; Scott Lundgren, @5twenty9, Carbon Black
Version: 1.1
Created: 24 January 2020
Last Modified: 12 April 2024


ID Mitigation Description
M1022 Restrict File and Directory Permissions

Consider using Group Policy to configure and block additions/modifications to W32Time DLLs. [4]

M1024 Restrict Registry Permissions

Consider using Group Policy to configure and block modifications to W32Time parameters in the Registry. [4]


ID Data Source Data Component Detects
DS0017 Command Command Execution

Monitor executed commands and arguments that may abuse time providers to execute DLLs when the system boots.

DS0011 Module Module Load

There is no restriction on the number of custom time providers registrations, though each may require a DLL payload written to disk. [3]

DS0009 Process Process Creation

Monitor newly executed processes, such as the W32tm.exe utility. [4] The Sysinternals Autoruns tool may also be used to analyze auto-starting locations, including DLLs listed as time providers. [5]

DS0024 Windows Registry Windows Registry Key Modification

Monitor for changes made to windows registry keys and/or values modifying W32Time information in the Registry.