Active Directory Service Accounts

There are many different types of accounts in a typical Active Directory environment. These include user accounts, computer accounts, and a particular type of account called a service account.

A service account is a special type of account that serves a specific purpose for services, and ultimately, applications in the environment.

These special-purpose Active Directory accounts are also the subject of cybersecurity risks in the environment.

What is a service account? What special privileges does it have on local systems? What cybersecurity risks can relate to service accounts used in the environment? How can IT admins find weak or non-expiring passwords used in Active Directory for service accounts?

What is a Windows service?

As mentioned at the outset, specific Active Directory accounts serve different purposes in Active Directory Domain Services (ADDS). You can assign Active Directory accounts as service accounts, a special-purpose account that most organizations create and use to run Windows services located on Windows Servers in their environment.

To understand the role of the service account, what is a Windows service? The Windows Service is a component of Microsoft Windows operating systems, both client and server, that allows long-running processes to execute and run for the duration of the time the host is running.

Unlike an application executed by an end-user, a Windows Service is not executed by an end-user logged into the system. Services run in the background and start when the Windows host initially starts up, depending on the service's configured behavior.

What is a Windows Service account?

Even though a Windows Service is not run interactively by an end-user who logs into the Windows system, it needs to have a Windows service account to allow the service to run under a specific user's context with special permissions.

A Windows Service, like any other process, has a security identity. This security identity determines the rights and privileges that it inherits both on the local machine and across the network.

It is essential to keep this security identity in mind as this determines how much potential the service account has to damage the local system where it is running and across the network. Following the least privileged best practice model regarding service, accounts help to ensure the service account does not have overprovisioned permissions, both locally and across the network.

The Windows Service can run under a local Windows user account, an Active Directory domain user account, or the special LocalSystem account. What differences exist between running a Windows Service account under a local Windows user account, an Active Directory domain user account, or the special LocalSystem account?

  • Local Windows user account - A local Windows user is a user that exists only on the local SAM database of the local Windows Server or client operating system. The account is only local and not tied to Active Directory in any way. There are limitations to using a local Windows user for a service. These include the inability to support Kerberos mutual authentication and challenges when the service is directory-enabled. The local Windows Service account, however, cannot damage the local Windows system. The local Windows user is limited when used for a service account.
    • Active Directory domain user account - A domain user account that resides in Active Directory Domain Services (ADDS) is the preferred type of account for a Windows Service. It allows taking advantage of various security features found in Windows and ADDS. The Active Directory user assumes all the permissions both locally and across the network and permissions granted to groups to which it belongs. Also, it can support Kerberos mutual authentication. Keep in mind that Active Directory domain user accounts used for Windows Service accounts should never be a member of administrator groups.
      • When a domain account is selected to run a Windows Service, it is granted the logon as a service right on the local computer where the service will run.
  • LocalSystem account – Using the special LocalSystem account is a dual-edged sword. On the one hand, using the LocalSystem account for a Windows Service allows the service to have unrestricted access to the Windows system, which may help prevent issues interacting with Windows components. However, this serves as a tremendous security disadvantage since the service could potentially damage the system or be the subject of a cyberattack. If compromised, a Windows Service running under LocalSystem has administrator access across the board.

Windows Service accounts are critical accounts in the environment. Choosing the right type of user account to run a Windows Service helps ensure the service functions correctly and has the appropriate permissions. What are common service account practices that can introduce cybersecurity risks in the environment?

Common service account practices

Since service accounts are special-purpose accounts that determine the security identity of business-critical applications in the environment, it is typical for service account passwords to have the flag set for password never expires.

The thought is that a service account password that expires will cause the business application to fail once the logon times out and the logon session refreshes with the domain controller. It is true. An expired password can certainly cause unwanted behavior with an application backed by the service account.

With the number of Windows Service accounts found in most environments, it can become difficult to manage service accounts with expiring passwords. However, it is certainly best from a security perspective.

password to never expire
Setting a service account password to never expire

It may also be common in some organizations to see service accounts with the same passwords set for multiple service accounts. The thought is that having the same password set for multiple service accounts helps to ease the burden of documenting passwords since it is shared between multiple accounts.

However, this can also be a dangerous practice. If an organization has a breach of a single service account, accounts with the same password are also at risk. It is best to keep passwords unique between all Active Directory accounts, including service accounts.

Overall, managing service accounts and service account passwords can become overwhelming even in small environments running a large number of Windows Services controlling business-critical applications.

It can be a challenge merely identifying service accounts with passwords set not to expire and those service accounts that may have the same password set. How can organizations easily maintain visibility to these types of account security issues?

Managing and Maintaining Service Accounts with Specops Password Auditor

Specops Password Auditor is a great free tool that helps to gain visibility to Active Directory account security issues in the environment. It can help quickly identify accounts, including service accounts, that may have the password set not to expire flag and configured with identical passwords.

Below, Specops Password Auditor points out several service account security issues, including:

  • Breached passwords
  • Identical passwords
  • Password never expires
Specops Password Auditor
Specops Password Auditor gives visibility to weak service account practices

You can get further detail from Specops Password Auditor by drilling into the various categories to see a more detailed view of the account issues. Below is a detailed view of the password never expires accounts. It is easy to pinpoint service accounts configured with a static, non-expiring password.

Viewing service accounts with password never expires flag set

Using Specops Password Auditor, you can quickly get a handle on service accounts in Active Directory that may have security issues that need to be corrected.

Wrapping Up

Managing and securing service accounts in your Active Directory environment is an essential step in your environment's overall security. Service accounts are vital as they provide the security context, rights, and permissions to both local resources and network resources for the services they back.

There are many common, insecure practices in dealing with service accounts in many enterprise environments, including passwords that do not expire, identical passwords, and even breached passwords configured. a

Specops Password Auditor helps to gain quick visibility to all account security issues in your environment, including service accounts, so IT admins can quickly remediate these.

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