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OOTW / Chapter I - Foundation / 01. Operating Systems / Windows / 08. Registry

Registry

Windows stores a large amount of configuration information.

Examples include:

  • Installed Software
  • User Preferences
  • Service Configuration
  • Network Settings
  • Security Configuration
  • Application Settings

This information is commonly stored within the Windows Registry.


Why This Matters

Many Windows components depend on the Registry.

Examples include:

ComponentRegistry Usage
ApplicationsConfiguration
ServicesStartup Configuration
WindowsSystem Settings
UsersPersonal Preferences
Security FeaturesSecurity Configuration

What Is The Registry?

The Registry is a hierarchical database used by Windows to store configuration information.

Conceptually:

Windows
        ↓
Reads Registry
        ↓
Obtains Configuration

Examples:

Wallpaper Settings
Service Configuration
Installed Applications

Many Windows components read Registry information during startup and operation.


Registry Structure

The Registry is organized as a hierarchy.

Conceptually:

Registry
├── Key
│   ├── Subkey
│   └── Value

This structure resembles directories and files within a file system.

Example:

Registry
↓
Key
↓
Subkey
↓
Value

Registry Hives

The top-level sections of the Registry are known as:

Hives

Common examples include:

HivePurpose
HKEY_LOCAL_MACHINE (HKLM)System-wide configuration
HKEY_CURRENT_USER (HKCU)Current user settings
HKEY_USERS (HKU)User profiles
HKEY_CLASSES_ROOT (HKCR)File associations
HKEY_CURRENT_CONFIG (HKCC)Hardware configuration

Operators frequently encounter HKLM and HKCU.


Registry Keys

Keys are similar to directories.

Example:

HKLM
└── SOFTWARE

A key may contain:

  • Additional keys
  • Values

Conceptually:

Key
↓
Contains
↓
Subkeys + Values

Registry Values

Values contain the actual configuration data.

Example:

Wallpaper = wallpaper.jpg

Conceptually:

Registry Key
    ↓
Value Name
    ↓
Value Data

Examples:

InstallPath = C:\Program Files\App
Start = 2

Viewing The Registry

Registry Editor:

regedit.exe

Conceptually:

Registry
↓
Regedit
↓
Browse Configuration

Command Line Access

Command Prompt:

reg query HKLM\SOFTWARE

PowerShell:

Get-ItemProperty HKLM:\SOFTWARE

The Registry can be queried and modified from the command line.


User Configuration

User-specific settings commonly reside within:

HKCU

Examples include:

  • Desktop Settings
  • Application Preferences
  • Environment Configuration

Conceptually:

Alice Logs In
        ↓
HKCU Maps To
        ↓
Alice's Settings

Different users may therefore have different configurations.


System Configuration

System-wide settings commonly reside within:

HKLM

Examples include:

  • Installed Software
  • Drivers
  • Services
  • Security Settings

Changes to HKLM frequently affect all users of the system.


Services and the Registry

Windows services are heavily configured through the Registry.

Examples include:

  • Service Startup Type
  • Service Account
  • Service Path

Conceptually:

Service
    ↓
Reads Registry
    ↓
Obtains Configuration

Many service investigations eventually involve Registry analysis.


Startup Locations

The Registry contains locations commonly used for automatic execution.

Examples include:

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
HKLM\Software\Microsoft\Windows\CurrentVersion\Run

Programs configured here may automatically launch during logon.

These locations are frequently examined during investigations.


Security Considerations

The Registry is a common location for:

  • Persistence
  • Configuration Abuse
  • Malware Storage
  • Security Configuration

Questions operators commonly ask include:

  • What changed?
  • What executes automatically?
  • What software was installed?
  • What configuration appears unusual?

Registry analysis is often a key part of investigations.


Operator Perspective

When approaching an unfamiliar Windows system, Operators typically ask:

Configuration

  • What settings are configured?
  • What software is installed?

Users

  • What user settings exist?
  • Which users have logged on?

Services

  • How are services configured?
  • Which services start automatically?

Persistence

  • What executes during startup?
  • Are unusual Registry entries present?

Security

  • Has malware modified the Registry?
  • Have security settings changed?
  • Have persistence mechanisms been added?

Many investigations eventually involve Registry analysis.


Key Takeaways

  • The Registry is a hierarchical configuration database.
  • Windows relies heavily on Registry information.
  • Registry information is organized into hives, keys, and values.
  • HKLM commonly stores system-wide settings.
  • HKCU commonly stores user-specific settings.
  • The Registry can be viewed using Regedit.
  • Services frequently store configuration in the Registry.
  • Startup locations often exist within the Registry.
  • The Registry is a common location for persistence mechanisms.
  • Understanding the Registry is essential for both offensive and defensive operations.

The next lesson explores Telemetry and how Windows records system activity.