Memo / Windows registry

21 Jun 2020

Explanation

The Windows Registry is a hierarchical database that stores low-level settings for the Windows OS and applications using the registry. This is a brief summary of How it is and how to browse / edit it.

Opening with regedit.exe

First, open the registry with regedit.exe. We have 5 root keys there. placeholder

1. HKEY_CLASSES_ROOT(HKCR)

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A section to manage file type associations.
Provides a view of the registry that merges the information from HKEY_LOCAL_MACHINE\Software\Classes and HKEY_CURRENT_USER\Software\Classes.
HKEY_LOCAL_MACHINE\Software\Classes holds default settings that can apply to all users on the local computer.
HKEY_CURRENT_USER\Software\Classes key contains settings that override that default settings.

2. HKEY_CURRENT_USER(HKCU)

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Information about the user currently logged in.
HKCU\Software holds user-level settings for the most of the software.
%USERPROFILE%\AppData\Local\Microsoft\Windows\Usrclass.dat and %LocalAppData%\Microsoft\Windows\Usrclass.dat hold the data.

3. HKEY_LOCAL_MACHINE(HKLM)

placeholder

Majority of the configuration information for the software we install and Windows operating system itself.

BCD00000000

Boot configuration Database.
Replaced boot.ini of Windows XP

HARDWARE

Holds data pertaining to the BIOS, processors and other hardware devices.

SAM

Database for Security Accounts Manager. Need SYSTEM account to access.
Stored in %SystemRoot%\System32\Config\SAM

SECURITY

Need SYSTEM account to access.
Stored in %SystemRoot%\System32\Config\SECURITY

SOFTWARE

Most commonly accessed from the HKLM hive. Organized alphabetically by the software vendor.
HKEY_LOCAL_MACHINE\SOFTWARE\Classes subkey of this key describes various UI details including extensions.
%SystemRoot%\System32\Config\SOFTWARE

SYSTEM

Stored in %SystemRoot%\System32\Config\SYSTEM.

4. HKEY_USERS(HKU)

placeholder

Stores all of the settings for all user profiles actively loaded on the system.

5. HKEY_CURRENT_CONFIG(HKCC)

placeholder

Information about the hardware profile that is used by the local computer at system setup.

Stored data type

These are the examples of the stored data type of Windows registry.

REG_BINARY : Binary value.
REG_DWORD : DWORD (32bit), used for a regular integer value.
REG_QWORD : QWORD (64bit), used for a 64-bit integer value.
REG_SZ : String value.
REG_EXPAND_SZ : String that can contain environment variables, often used for system paths.
REG_MULTI_SZ : Multiple string used to represent values that contains lists or multiple values, separated by a NULL character
REG_RESOURCE_LIST : Series of nested arrays that is designed to store a resource list used by a hardware device driver or one of the physical devices it controls.
REG_LINK : A Unicode symbolic link.
REG_NONE : No defined type value.

How to get SID of users

1. Get SID of a local user

C:\Users\Administrator>wmic useraccount where name='Administrator' get sid
SID
S-1-5-21-299884335-592523710-3968369954-500

2. Get SID for current logged in domain user

C:\Users\Administrator>whoami /user

USER INFORMATION
----------------

User Name              SID
====================== ===========================================
mydomain\administrator S-1-5-21-299884335-592523710-3968369954-500

Browse Windows registry with command prompt

1. Listing subkeys

C:\Users\Administrator>reg query "HKLM\SOFTWARE\Microsoft\Windows"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\ClickNote
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\DWM
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\EnterpriseResourceManager
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\HTML Help
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\ITStorage
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\ScheduledDiagnostics
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\ScriptedDiagnosticsProvider
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Shell
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\SoftwareInventoryLogging
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\StreamProvider
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Tablet PC
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\TabletPC
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Windows Error Reporting
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Windows Search

2. Extract a specific value of a key

C:\Users\Administrator>reg query "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RUN" /v VBoxTray

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RUN
    VBoxTray    REG_EXPAND_SZ    %SystemRoot%\system32\VBoxTray.exe

Browse / Edit Windows registry with PowerShell

1. Listing all exposed drives including HKLM and HKCU

PS C:\Users\Administrator> get-psdrive

Name           Used (GB)     Free (GB) Provider      Root                                               CurrentLocation
----           ---------     --------- --------      ----                                               ---------------
Alias                                  Alias
C                  16.14         33.37 FileSystem    C:\                                            Users\Administrator
Cert                                   Certificate   \
D                   0.06          0.00 FileSystem    D:\
Env                                    Environment
Function                               Function
HKCU                                   Registry      HKEY_CURRENT_USER
HKLM                                   Registry      HKEY_LOCAL_MACHINE
Variable                               Variable
WSMan                                  WSMan

2. Navigate to the local machine registry root key

We can use cd command.

PS C:\Users\Administrator> cd HKLM:\
PS HKLM:\>

Or we can use Set-Location for PowerShell.

PS C:\Users\Administrator> set-location -path HKLM:\SOFTWARE
PS HKLM:\SOFTWARE>

3. Output sub keys

PS HKLM:\SOFTWARE> Get-Childitem


    Hive: HKEY_LOCAL_MACHINE\SOFTWARE


Name                           Property
----                           --------
Classes
Clients
Intel
Microsoft
ODBC
Oracle
Partner
Policies
RegisteredApplications         File Explorer             :
                               SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Capabilities
                               Internet Explorer         : SOFTWARE\Microsoft\Internet Explorer\Capabilities
                               Paint                     :
                               SOFTWARE\Microsoft\Windows\CurrentVersion\Applets\Paint\Capabilities
                               Windows Address Book      : Software\Clients\Contacts\Address Book\Capabilities
                               Windows Disc Image Burner : Software\Microsoft\IsoBurn\Capabilities
                               Windows Media Player      : Software\Clients\Media\Windows Media Player\Capabilities
                               Windows Photo Viewer      : Software\Microsoft\Windows Photo Viewer\Capabilities
                               Windows Search            : Software\Microsoft\Windows Search\Capabilities
                               Wordpad                   :
                               Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad\Capabilities

4. Output registry entries in a readable form

PS HKLM:\> Get-ItemProperty -path HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion


ProgramFilesDir          : C:\Program Files
CommonFilesDir           : C:\Program Files\Common Files
ProgramFilesDir (x86)    : C:\Program Files (x86)
CommonFilesDir (x86)     : C:\Program Files (x86)\Common Files
CommonW6432Dir           : C:\Program Files\Common Files
DevicePath               : C:\Windows\inf
MediaPathUnexpanded      : C:\Windows\Media
ProgramFilesPath         : C:\Program Files
ProgramW6432Dir          : C:\Program Files
SM_ConfigureProgramsName : Set Program Access and Defaults
SM_GamesName             : Games
PSPath                   : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVer
                           sion
PSParentPath             : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
PSChildName              : CurrentVersion
PSDrive                  : HKLM
PSProvider               : Microsoft.PowerShell.Core\Registry

5. Add a new key

PS HKCU:\> new-item 'HKCU:\Testkey'

    Hive: HKEY_CURRENT_USER

Name                           Property
----                           --------
Testkey

6. Add a new property to a key

PS HKCU:\> new-itemproperty -LiteralPath 'HKCU:Testkey' -Name 'param1' -PropertyType 'String' -Value 'test'


param1       : test
PSPath       : Microsoft.PowerShell.Core\Registry::HKEY_CURRENT_USER\Testkey
PSParentPath : Microsoft.PowerShell.Core\Registry::HKEY_CURRENT_USER
PSChildName  : Testkey
PSDrive      : HKCU
PSProvider   : Microsoft.PowerShell.Core\Registry

7. Retrieve properties from a key

PS HKCU:\> Get-ItemProperty -path HKCU:\Testkey


param1       : test
PSPath       : Microsoft.PowerShell.Core\Registry::HKEY_CURRENT_USER\Testkey
PSParentPath : Microsoft.PowerShell.Core\Registry::HKEY_CURRENT_USER
PSChildName  : Testkey
PSDrive      : HKCU
PSProvider   : Microsoft.PowerShell.Core\Registry

8. Retrieve a value of single property from a key

PS HKCU:\> Get-ItemPropertyvalue -LiteralPath 'HKCU:Testkey' -Name param1
test

9. Update a value of single property

PS HKCU:\> set-itemproperty -Literalpath 'HKCU:Testkey' -Name param1 -Value 'test-test'

PS HKCU:\> Get-ItemPropertyvalue -LiteralPath 'HKCU:Testkey' -Name param1
test-test

10. Existing check of a key

PS HKCU:\> Test-Path -LiteralPath "HKCU:\testkey"
True

11. Delete a key

PS HKCU:\> Remove-Item -LiteralPath "HKCU:\Testkey"

PS HKCU:\> Test-Path -LiteralPath "HKCU:\testkey"
False

1n4r1.github.io

Memo / Windows registry

Explanation

Opening with regedit.exe

1. HKEY_CLASSES_ROOT(HKCR)

2. HKEY_CURRENT_USER(HKCU)

3. HKEY_LOCAL_MACHINE(HKLM)

BCD00000000

HARDWARE

SAM

SECURITY

SOFTWARE

SYSTEM

4. HKEY_USERS(HKU)

5. HKEY_CURRENT_CONFIG(HKCC)

Stored data type

How to get SID of users

1. Get SID of a local user

2. Get SID for current logged in domain user

Browse Windows registry with command prompt

1. Listing subkeys

2. Extract a specific value of a key

Browse / Edit Windows registry with PowerShell

1. Listing all exposed drives including HKLM and HKCU

2. Navigate to the local machine registry root key

3. Output sub keys

4. Output registry entries in a readable form

5. Add a new key

6. Add a new property to a key

7. Retrieve properties from a key

8. Retrieve a value of single property from a key

9. Update a value of single property

10. Existing check of a key

11. Delete a key

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