The One Step Most Organizations Miss with Active Directory

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The One Step Most Organizations Miss with Active Directory Security

Active Directory (AD) is still the backbone of identity for most enterprises. It manages user authentication, controls access to resources, and ties directly into cloud and hybrid environments. That central role makes it one of the most targeted systems for attackers.

Despite years of guidance, many organizations continue to make the same mistakes. The problem is not a lack of awareness but the absence of one critical step: a proactive Active Directory security assessment. Most companies only uncover risks when a penetration test or an incident response engagement forces them to look. By that point, attackers already know the weaknesses.

This article outlines three of the most common ways Active Directory environments are compromised, and why a focused security assessment is the missing piece in most defense strategies.

1. Administrative Access Extends Further Than You Think

When teams review AD security, they often start by counting the number of accounts in the Domain Admins group. That’s a necessary step, but it’s far from sufficient. Privileged rights are often distributed across nested groups, old delegations, or forgotten service accounts.

Active Directory Admins vs Delegated Rights

• Default Domain Administrator account has default rights to Active Directory and needs to be secured.
• Active Directory Administrator accounts, which includes the domain Administrators group and all members, require regular review and scrutiny.
• Built-in groups such as Account Operators, Schema Admins, and Server Operators often hold accounts that no longer need elevated privileges.
• Delegated permissions at the domain root can grant rights to AD objects just as powerful as Domain Admins but rarely show up in simple group membership reviews.
• Service accounts may remain in administrative groups because teams are afraid of breaking applications, even though the original purpose no longer applies.

Privileged Account Hygiene

Attackers exploit this sprawl. A compromised help desk account with broad delegation rights can be just as valuable as a true Domain Admin.

Practical steps:

• Scrutinize Active Directory Admins and perform regular review to ensure membership is appropriate.
• Keep built-in groups empty unless absolutely required.
• Apply delegation at the OU level, not the domain root.
• Rotate privileged credentials regularly and avoid shared accounts.
• Set the “sensitive” flag and add administrative accounts to the Protected Users group.

2. Virtualization as a Direct Path to Compromise

VMware Security and AD

• ESXi hosts that are joined to Active Directory automatically grant administrative rights to the ESX Admins group in Active Directory. By default, this group inherits significant rights, creating a hidden escalation path.
• vCenter servers often sit on networks accessible to far too many users. If attackers compromise vCenter, they can manipulate virtual domain controllers at will.
• Administrator groups in VMware and ESXi frequently contain more accounts than necessary, expanding the blast radius of a single credential theft.

Treating Virtualization as Tier 0

A VMware administrator can snapshot a domain controller, copy its virtual disk, and extract the Active Directory database offline. That database contains every credential in the forest. Once an attacker holds that file, they effectively own the environment.

Practical steps:

• Treat vSphere, vCenter, and ESXi hosts as Tier 0 assets, equal in importance to domain controllers.
• Do not join ESXi hosts directly to AD.
• Restrict vCenter access to dedicated admin networks only.
• Encrypt domain controller disks with BitLocker or an equivalent solution to prevent offline credential extraction.

3. Certificate Services Misconfigurations

Active Directory Certificate Services (ADCS) is another area where dangerous defaults persist. Many organizations rely on ADCS for Wi-Fi authentication, internal SSL, or smart cards, but they rarely review the configuration after initial setup.

ADCS Security Risks

• Certificate templates that allow users to define the subject name make it possible to request certificates on behalf of administrators or domain controllers.
• Broad auto-enroll permissions mean unprivileged users can automatically request powerful certificates.
• Default ADCS deployments do not enable auditing, leaving no record of who is requesting or issuing certificates.

Locksmith and ADCS Auditing

A single insecure template can give an attacker the ability to mint valid credentials for privileged accounts. From there, domain compromise is inevitable.

Practical steps:

• Audit all certificate templates for dangerous options such as subject name specification and auto-enrollment.
• Remove unnecessary enrollment rights from broad groups.
• Enable full auditing on ADCS servers.
• Use tools like Locksmith to scan the environment, identify risky templates, and prioritize remediation.

Why a Proactive Assessment Is the Missing Step

Most organizations believe they are protected because they run annual penetration tests or commission red team exercises. While valuable, these are reactive measures. They demonstrate what an attacker could do, but they do not replace the need for a structured, proactive review of Active Directory.

A dedicated Active Directory security assessment looks at:

• Administrative group memberships and delegation
• Privileged account hygiene
• Domain-root permissions
• Virtualization integration such as VMware
• Certificate Services templates and auditing
• Integration points with Azure AD and cloud platforms
  
• And more!

Tools such as BloodHound, PingCastle, Purple Knight, and Locksmith provide useful data, but context matters. The real value comes from prioritizing findings, validating risks, and producing a consolidated roadmap that the organization can act on.

Practical Checklist for Hardening Active Directory

1. Audit the domain Administrators group and all nested groups (which includes Domain Admins).
2. Review delegated permissions at the domain root.
3. Empty unnecessary built-in groups such as Account Operators and Schema Admins.
4. Remove service accounts from administrative groups and rotate their passwords.
5. Place privileged accounts in the Protected Users group and set the sensitive account flag.
6. Treat VMware, vSphere, and ESXi hosts as Tier 0 assets.
7. Restrict vCenter to dedicated admin networks.
8. Encrypt domain controller disks to prevent offline credential theft.
9. Audit all ADCS templates and remove unsafe permissions.
10. Enable auditing for Certificate Services and monitor regularly

Active Directory compromises are not driven by exotic exploits. They are driven by overprovisioned accounts, overlooked virtualization settings, and insecure certificate services. Each of these risks is preventable, but only if organizations take the time to look for them.

The one step most organizations miss is the most straightforward: a proactive Active Directory security assessment. Identifying weaknesses before attackers do is the difference between resilience and compromise.

TrustedSec continues to help organizations strengthen their identity infrastructure by exposing hidden risks and providing actionable remediation guidance. For more information, please get in touch with us for assistance!