Offensive Security in Active Directory: Top 5 Risks and Pentesting Tools

Active Directory (AD) is the heart of identity and access management in most enterprise Windows environments. It controls authentication, authorization, and policies for users, groups, and machines. Because of this central role, compromising AD often means owning the entire enterprise.

From an offensive security perspective, Active Directory presents a rich attack surface. Pentesters and red teamers frequently encounter poorly configured environments, legacy systems, and a lack of monitoring that make AD compromise not only possible, but often inevitable if defenses aren’t hardened.

In this blog post, we’ll cover:

• The Top 5 Risks in Active Directory, with practical attack scenarios.
• The Top 5 Tools for Windows pentesting commonly used during internal engagements.
• The Top 5 Tools for Linux pentesting for attackers working from Unix-based systems.

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🔴 Top 5 Risks in Active Directory

1. Weak or Reused Passwords

• Why it matters: Password spraying and Kerberoasting rely on weak service account or user credentials. Since AD often integrates with many systems, reused passwords extend the blast radius.
• Attack scenario:
  • An attacker runs Kerbrute to enumerate valid users via Kerberos.
  • They then spray common passwords (e.g., Spring2025!) across accounts.
  • Once credentials are found, lateral movement becomes trivial.
• Defense: Enforce long, unique passwords, enable account lockout policies, and monitor failed login attempts.

2. Over-Privileged Accounts

• Why it matters: Excessive group memberships (Domain Admins, Enterprise Admins) shorten the path to complete compromise. Even “normal” users with local admin rights on multiple machines are dangerous.
• Attack scenario:
  • Using BloodHound, a tester maps an attack path showing that a helpdesk user has local admin rights on a workstation where a Domain Admin frequently logs in.
  • By pivoting through that machine and stealing tokens with Mimikatz, the pentester escalates to Domain Admin.
• Defense: Apply the principle of least privilege (PoLP), use tiered administration, and regularly audit group memberships.

3. Unpatched Domain Controllers

• Why it matters: Domain Controllers (DCs) are the “keys to the kingdom.” Exploits like ZeroLogon (CVE-2020-1472) and PrintNightmare highlight the danger of unpatched AD infrastructure.
• Attack scenario:
  • A pentester runs an Impacket script (zerologon_tester.py) against a DC and finds it vulnerable.
  • Within seconds, they reset the machine account password and gain full domain takeover.
• Defense: Apply patches immediately, isolate DCs, and monitor for anomalous RPC/Netlogon activity.

4. Misconfigured Delegations

• Why it matters: Delegation allows a service to impersonate a user. If misconfigured, it can let attackers impersonate higher-privileged accounts.
• Attack scenario:
  • The pentester enumerates accounts with unconstrained delegation using PowerView.
  • By compromising one such account, they impersonate a Domain Admin via Kerberos ticket theft.
• Defense: Avoid unconstrained delegation. Use resource-based constrained delegation (RBCD) carefully, and audit for misconfigurations.

5. Lack of Monitoring & Detection

• Why it matters: Even if an attacker gains persistence, defenders can still catch them. But many environments don’t log critical events or aggregate them for analysis.
• Attack scenario:
  • A red teamer runs Rubeus to request golden tickets and continues using forged Kerberos tickets for months.
  • Without proper SIEM alerts on Kerberos anomalies, the attack remains invisible.
• Defense: Enable advanced logging (Sysmon, Event ID 4768/4769), use anomaly detection on Kerberos tickets, and implement honey accounts.

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🪟 Top 5 Tools for Windows Pentesting

Windows environments allow direct interaction with AD components. These are the tools every red teamer keeps ready:

1. Mimikatz
   • Extracts plaintext passwords, NTLM hashes, and Kerberos tickets.
   • Example: sekurlsa::logonpasswords dumps cached credentials.
2. BloodHound (with SharpHound)
   • Visualizes AD attack paths and privilege escalation opportunities.
   • Example: Run SharpHound on a compromised host, import results, and find shortest path to Domain Admin.
3. Rubeus
   • A Kerberos post-exploitation toolkit.
   • Example: Run Rubeus asreproast to dump AS-REP roastable accounts.
4. PowerView
   • PowerShell toolkit for AD enumeration.
   • Example: Get-DomainTrust lists domain trust relationships useful for forest attacks.
5. Responder
   • Captures credentials via LLMNR/NBT-NS poisoning.
   • Example: Run responder -I eth0 to listen for hashes across the network.

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🐧 Top 5 Tools for Linux Pentesting

When operating from Linux (common for external consultants or red teams), these tools replicate or extend Windows capabilities:

1. Impacket
   • Python library with tools for SMB, Kerberos, and MSRPC attacks.
   • Example: secretsdump.py extracts NTDS.dit hashes after DC compromise.
2. CrackMapExec (CME)
   • Automates spraying, enumeration, and lateral movement.
   • Example: cme smb 192.168.1.0/24 -u users.txt -p Summer2025! to check valid logins.
3. Evil-WinRM
   • Provides a stable WinRM shell for remote management.
   • Example: evil-winrm -i target -u user -p password.
4. Kerbrute
   • Enumerates and brute-forces Kerberos accounts.
   • Example: kerbrute userenum -d corp.local users.txt.
5. Nmap (with NSE scripts)
   • Essential for service enumeration and AD reconnaissance.
   • Example: nmap --script=smb-enum-shares,smb-os-discovery -p445 192.168.1.10.

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🛡️ Wrapping Up

Active Directory security is a never-ending battle between attackers looking for weak links and defenders racing to patch, harden, and monitor their environments.

From an offensive security perspective, the key risks remain:

• Weak credentials
• Over-privileged accounts
• Unpatched DCs
• Misconfigured delegations
• Lack of monitoring

And the key toolkits for pentesters on Windows (Mimikatz, BloodHound, Rubeus, PowerView, Responder) and Linux (Impacket, CME, Evil-WinRM, Kerbrute, Nmap) remain essential.

The lesson is clear: if you don’t know your AD weaknesses, attackers will find them for you. Regular offensive testing is the best defense.

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