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Preventing Access: Active Directory Authentication Protocols. Active Directory Authentication Protocols play a pivotal role in safeguarding digital assets against unauthorized access within organizational networks. The fundamental components of authentication techniques are protocols that guarantee that only authenticated users access resources. Understanding the dynamics of these protocols is essential for implementing robust security measures and fortifying network defences against potential breaches.

Preventing Access: Active Directory Authentication Protocols

Shortcomings of Active Directory Authentication

IT teams in businesses now need help to provide access controls and management in a heterogeneous IT environment. Most of the time, we have administrators utilize LDAP to authenticate Linux and macOS devices to AD, adding another layer we must integrate and maintain.

Instead of a single, authoritative, centralized directory platform for authorization and authentication services, organizations wind up with several “mini directories.” In addition to heterogeneous operating systems, cloud-based services and software-as-a-service (SaaS) have seen a sharp increase in popularity in recent years.

The IAM landscape presents a good number of problems with this adoption. For instance, administrators isolate most SaaS services, which makes authorization-related management more difficult. Additionally, onboarding people in a SaaS-first environment is laborious and time-consuming because it involves users from several departments.

Active Directory Authentication Protocols

A receiving entity (like a server) can confirm another party’s user identification with an authentication protocol. We also use AD user authentication protocols to secure communication between computer networks. Here are the authentication protocols administrators mainly use in AD.

Overview of NTLM

Windows NT LAN Manager or NTLM is a suite of protocols used for client authentication within an Active Directory domain environment. Use NTLM (Windows NT LAN Manager) to verify a client’s identity when they access a resource within an Active Directory domain—the NTLMv1, NTLMv2, and NTLM2 Session protocols we include in this package.

Main issue with NTLM, is that it is susceptible to brute force and pass-the-hash attacks

NTLM employs a challenge-response authentication method, wherein the domain controller or target computer verifies the client’s stored hash for a match. Upon validation, access to the granted resource. NTLM passwords are stored either in the SAM database of the registry during local authentication or in the domain controller’s ntds.dit file. Here’s how the process unfolds:

  1. The client initiates an authentication request.
  2. The resource challenges authentication by providing a 16-bit random number.
  3. The client combines the challenge with the stored hash and responds.
  4. The response, comprising the username, challenge, and response, is forwarded to the domain controller by the resource.
  5. The domain controller receives the forwarded response and checks it against the stored hash in ntds.dit. If it matches, access to the resource is either granted or denied based on the access status.

Kerberos enhances security by incorporating secret-key cryptography and third-party ticket authorization into its authentication framework. It embodies 3entities of client, server, and Key Distribution Center (KDC). The KDC is the Authentication Server (AS) and the Ticket Granting Server (TGS).

Here’s how the Kerberos authentication process works:

  1. The client requests an authentication ticket called the Ticket Granting Ticket (TGT).
  2. The KDC authenticates the client’s credentials and provides an encrypted TGT and a session key.
  3. The client stores the TGT until it expires and requests another when needed.
  4. When accessing a resource, the client presents the current TGT to the TGS and the resource’s Service Principal Name (SPN).
  5. The TGS provides a valid session key for the resource to the client.
  6. The client employs the session key to access the resource securely.

Additionally, a Golden Ticket attack is a malicious cybersecurity attack where a threat actor tries to access user data stored in Microsoft Active Directory (AD) to obtain access to an organization’s domain (files, devices, domain controllers, etc.). It circumvents standard authentication by using flaws in the Kerberos identity authentication protocol, which attackers utilize to gain access to the AD. Click on this link to learn more about Golden Ticket attacks.

Is not limited to use for authentication. Also use it to update database entries or locate files and devices on a network. Since LDAP is more easily misconfigured and not as secure by default, most environments do not utilize it for pure authentication. For instance, LDAP transmits authentication over the network in plaintext (without setting LDAPS).

With TLS/SSL, LDAP is easier to use. Through port 389, the client sends information requests to the LDAP server. The account name, domain name, and we include user passwords in what is known as a “bind request” process. The system provides access or information after comparing the password with the bound database.

We can use a client-server network protocol called Remote Authentication Dial-in User Service (RADIUS). When a client uses the Network Access Server (NAS) or Remote Access Server (RAS) to request access to a resource, RADIUS authentication starts. The RAS sends the authentication request to the RADIUS server.

After that, it compares the data with a database file kept locally or with another external source, such as Active Directory.

Choosing The Best Protocol For The Organization

So how to be successful in Preventing Access: Active Directory Authentication Protocols? Let’s point out few details.

Our protocol selection hinges upon the specific characteristics of our existing infrastructure and the demands posed by our applications. It’s crucial to recognize that every authentication method entails its own set of vulnerabilities and benefits. As we deliberate on various protocols, take into account several key considerations.

For instance, assess which applications require access and whether the chosen protocol seamlessly accommodates the expanding needs of our organization. Additionally, consider our staff’s familiarity with different protocols and prioritize options that align closely with our current infrastructure, thus reducing the necessity for extensive system overhauls.

How To Tell What Protocol We Are Using

  1. Review the device’s or service’s authentication settings: This may involve accessing a configuration file, management interface, or GUI. Look for settings about authentication and security.
  2. Identify the authentication protocol to utilize: Depending on the device or service, we may encounter specific protocol designations such as PAP, CHAP, MS-CHAP, or EAP.
  3. Inspect the logs: Many authentication services maintain authentication attempts and outcomes logs. Scrutinize the logs to detect any references to the authentication protocol employed.
  4. Utilize a network analyser: Wireshark captures and analyses network traffic. By capturing authentication traffic, we determine the protocol we can employ.
  5. Refer to the documentation: The documentation accompanying the device or service might furnish details regarding supported authentication protocols and their configuration procedures.

Insecure Protocols to Avoid

  1. Telnet: is unencrypted protocol and exposes login credentials in plaintext, rendering them vulnerable to eavesdropping and interception.
  2. FTP (File Transfer Protocol):Also sends login credentials in plaintext, making it easy for unauthorized individuals to intercept and misuse them to gain access to the system.
  3. SNMP (Simple Network Management Protocol): Employs a weak authentication mechanism, transmitting community strings in plaintext, thereby exposing it to spoofing and eavesdropping attacks.
  4. HTTP (Hypertext Transfer Protocol): Similarly sends login credentials in plaintext, making it susceptible to interception and replay attacks.
  5. SMB (Server Message Block): Utilized for file sharing on Windows systems, particularly older versions like SMBv1, are prone to vulnerabilities and ransomware attacks such as WannaCry.

In conclusion, it is advisable to avoid insecure authentication protocols and opt for more robust authentication mechanisms that offer encryption and defense against potential attacks.

Well, thank you for your time in reading Preventing Access: Active Directory Authentication Protocols. Let’s conclude. 

Preventing Access: Active Directory Authentication Protocols Conclusion

All in all, Active Directory Authentication Protocols are indispensable tools in modern cybersecurity, providing a crucial defence against unauthorized access. Organizations enhance their security stance and mitigate the risks of potential breaches by comprehending the significance and intricacies thereof. Continued vigilance and advancements in authentication technologies remains imperative in maintaining the integrity and confidentiality of sensitive data.


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Marion Mendoza

Marion Mendoza

Windows Server and VMware SME. Powershell Guru. Currently working with Fortune 500 companies responsible for participating in 3rd level systems support across the enterprise. Acting as a Windows Server engineer and VMware Specialist.

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