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• Definition: NTLM (NT LAN Manager) is a suite of Microsoft security protocols intended to provide authentication, integrity, and confidentiality to users within a network. It is primarily used in Windows environments.
• Function: Provides a challenge-response mechanism for authenticating users and securing communications, ensuring that passwords are not transmitted in plaintext.
• Components:

   * '''NTLMv1''': The original version of the protocol, offering basic authentication and security features.
   * '''NTLMv2''': An improved version that provides enhanced security features, including stronger encryption and more complex challenge-response mechanisms.
   * '''NTLMSSP (NT LAN Manager Security Support Provider)''': A protocol used for negotiating the NTLM authentication process.

• Features:

   * '''Challenge-Response Authentication''': Protects user credentials by never sending passwords over the network in plaintext.
   * '''Session Security''': Provides options for message integrity and confidentiality, including signing and encryption of messages.
   * '''Backward Compatibility''': Supports older Windows systems and applications, ensuring broad compatibility across different network environments.

• Usage: Commonly used in environments where Kerberos is not available or practical, such as standalone systems or during fallback scenarios.

• NTLM Authentication Process:

   1. **Negotiate Message**: The client sends a negotiate message to the server, indicating its supported NTLM options.
   2. **Challenge Message**: The server responds with a challenge message containing a random challenge.
   3. **Authenticate Message**: The client responds with an authenticate message containing the user's response to the challenge, encrypted with a hash of the user's password.
   4. **Verification**: The server verifies the response with the domain controller and either grants or denies access based on the result.

• Configuring NTLM in a Windows environment:

   * Access the Group Policy Editor (`gpedit.msc`).
   * Navigate to `Computer Configuration` > `Windows Settings` > `Security Settings` > `Local Policies` > `Security Options`.
   * Configure the `Network security: LAN Manager authentication level` policy to use NTLMv2 response only.

• Enabling NTLM auditing:

   * Use the Event Viewer to monitor NTLM authentication events by navigating to `Applications and Services Logs` > `Microsoft` > `Windows` > `NTLM`.

• NTLM: A suite of security protocols used for authenticating users and securing communications within a Windows network, utilizing a challenge-response mechanism to ensure credentials are protected and providing backward compatibility with older systems and applications.