userinit.exe

  • File Path: C:\WINDOWS\SysWOW64\userinit.exe
  • Description: Userinit Logon Application

Hashes

Type Hash
MD5 A83702100F695127901004594BAF8E84
SHA1 915600176F304363F04880110B978CB94FCC9F6C
SHA256 AF1519BEC6ADBE3815D082002803FD0570058C324A51F5BE15194A058FF03275
SHA384 4EC00E7A1073F8F096A4D2D05DF107B3F63DA23B3B6A993E15BE2F514F49174C73BF8E82F32A305675F58D94872A3B29
SHA512 52F330626CD2755035DAAB0A7B4EA7E48DC8DB14CAE27326B043618A1C9A2E592BD51E7D983422BA0E734D59FF07C95A9DEFBB933584CBA4ECCC70395C39EA33
SSDEEP 384:Uwo38oAephzq+dtPzq0zUQm9J7uEQN2VMQn7RgWbymWhBGy:Uj38k7zq+bLjBm9d5QN23nS5BT

Signature

  • Status: Signature verified.
  • Serial: 330000023241FB59996DCC4DFF000000000232
  • Thumbprint: FF82BC38E1DA5E596DF374C53E3617F7EDA36B06
  • Issuer: CN=Microsoft Windows Production PCA 2011, O=Microsoft Corporation, L=Redmond, S=Washington, C=US
  • Subject: CN=Microsoft Windows, O=Microsoft Corporation, L=Redmond, S=Washington, C=US

File Metadata

  • Original Filename: USERINIT.EXE
  • Product Name: Microsoft Windows Operating System
  • Company Name: Microsoft Corporation
  • File Version: 10.0.18362.1 (WinBuild.160101.0800)
  • Product Version: 10.0.18362.1
  • Language: English (United States)
  • Legal Copyright: Microsoft Corporation. All rights reserved.

Possible Misuse

The following table contains possible examples of userinit.exe being misused. While userinit.exe is not inherently malicious, its legitimate functionality can be abused for malicious purposes.

Source Source File Example License
sigma sysmon_suspicious_remote_thread.yml - '\userinit.exe' DRL 1.0
sigma proc_creation_win_logon_scripts_userinitmprlogonscript_proc.yml ParentImage\|endswith: '\userinit.exe' DRL 1.0
sigma proc_creation_win_susp_direct_asep_reg_keys_modification.yml - '\software\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit' DRL 1.0
sigma proc_creation_win_susp_userinit_child.yml title: Suspicious Userinit Child Process DRL 1.0
sigma proc_creation_win_susp_userinit_child.yml description: Detects a suspicious child process of userinit DRL 1.0
sigma proc_creation_win_susp_userinit_child.yml ParentImage\|endswith: '\userinit.exe' DRL 1.0
sigma registry_event_asep_reg_keys_modification.yml - '\Winlogon\Userinit' DRL 1.0
sigma registry_event_asep_reg_keys_modification_currentversion_nt.yml - '\Winlogon\Userinit' DRL 1.0
malware-ioc misp_invisimole.json "description": "Adding an entry to the \"run keys\" in the Registry or startup folder will cause the program referenced to be executed when a user logs in. (Citation: Microsoft Run Key) These programs will be executed under the context of the user and will have the account's associated permissions level.\n\nThe following run keys are created by default on Windows systems:\n* <code>HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Run</code>\n* <code>HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnce</code>\n* <code>HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows\\CurrentVersion\\Run</code>\n* <code>HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnce</code>\n\nThe <code>HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows\\CurrentVersion\\RunOnceEx</code> is also available but is not created by default on Windows Vista and newer. Registry run key entries can reference programs directly or list them as a dependency. (Citation: Microsoft RunOnceEx APR 2018) For example, it is possible to load a DLL at logon using a \"Depend\" key with RunOnceEx: <code>reg add HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\RunOnceEx\\0001\\Depend /v 1 /d \"C:\\temp\\evil[.]dll\"</code> (Citation: Oddvar Moe RunOnceEx Mar 2018)\n\nThe following Registry keys can be used to set startup folder items for persistence:\n* <code>HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\User Shell Folders</code>\n* <code>HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Shell Folders</code>\n* <code>HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Shell Folders</code>\n* <code>HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer\\User Shell Folders</code>\n\nThe following Registry keys can control automatic startup of services during boot:\n* <code>HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows\\CurrentVersion\\RunServicesOnce</code>\n* <code>HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\RunServicesOnce</code>\n* <code>HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows\\CurrentVersion\\RunServices</code>\n* <code>HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\RunServices</code>\n\nUsing policy settings to specify startup programs creates corresponding values in either of two Registry keys:\n* <code>HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\Explorer\\Run</code>\n* <code>HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\Explorer\\Run</code>\n\nThe Winlogon key controls actions that occur when a user logs on to a computer running Windows 7. Most of these actions are under the control of the operating system, but you can also add custom actions here. The <code>HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon\\Userinit</code> and <code>HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon\\Shell</code> subkeys can automatically launch programs.\n\nPrograms listed in the load value of the registry key <code>HKEY_CURRENT_USER\\Software\\Microsoft\\Windows NT\\CurrentVersion\\Windows</code> run when any user logs on.\n\nBy default, the multistring BootExecute value of the registry key <code>HKEY_LOCAL_MACHINE\\System\\CurrentControlSet\\Control\\Session Manager</code> is set to autocheck autochk *. This value causes Windows, at startup, to check the file-system integrity of the hard disks if the system has been shut down abnormally. Adversaries can add other programs or processes to this registry value which will automatically launch at boot.\n\n\nAdversaries can use these configuration locations to execute malware, such as remote access tools, to maintain persistence through system reboots. Adversaries may also use [Masquerading](https://attack.mitre.org/techniques/T1036) to make the Registry entries look as if they are associated with legitimate programs.", © ESET 2014-2018
malware-ioc part3.adoc userinit.exe © ESET 2014-2018
atomic-red-team index.md - Atomic Test #2: Winlogon Userinit Key Persistence - PowerShell [windows] MIT License. © 2018 Red Canary
atomic-red-team windows-index.md - Atomic Test #2: Winlogon Userinit Key Persistence - PowerShell [windows] MIT License. © 2018 Red Canary
atomic-red-team T1012.md reg query “HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit” MIT License. © 2018 Red Canary
atomic-red-team T1547.001.md The Winlogon key controls actions that occur when a user logs on to a computer running Windows 7. Most of these actions are under the control of the operating system, but you can also add custom actions here. The HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit and HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell subkeys can automatically launch programs. MIT License. © 2018 Red Canary
atomic-red-team T1547.004.md * Winlogon\Userinit - points to userinit.exe, the user initialization program executed when a user logs on MIT License. © 2018 Red Canary
atomic-red-team T1547.004.md - Atomic Test #2 - Winlogon Userinit Key Persistence - PowerShell MIT License. © 2018 Red Canary
atomic-red-team T1547.004.md ## Atomic Test #2 - Winlogon Userinit Key Persistence - PowerShell MIT License. © 2018 Red Canary
atomic-red-team T1547.004.md PowerShell code to set Winlogon userinit key to execute a binary at logon along with userinit.exe. MIT License. © 2018 Red Canary
atomic-red-team T1547.004.md Set-ItemProperty “HKCU:\Software\Microsoft\Windows NT\CurrentVersion\Winlogon" “Userinit” “Userinit.exe, #{binary_to_execute}” -Force MIT License. © 2018 Red Canary
atomic-red-team T1547.004.md Remove-ItemProperty -Path “HKCU:\Software\Microsoft\Windows NT\CurrentVersion\Winlogon" -Name “Userinit” -Force -ErrorAction Ignore MIT License. © 2018 Red Canary

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