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Introduction:
Active Directory (AD) is the cornerstone of most corporate networks, making it a prime target for attackers and a critical area for defensive hardening. This guide distills essential penetration testing techniques from TCM Security’s renowned course, providing a hands-on approach to identifying and exploiting common AD vulnerabilities to strengthen your organization’s security posture.
Learning Objectives:
- Understand the core attack vectors within an Active Directory environment.
- Master practical command-line techniques for enumeration, lateral movement, and privilege escalation.
- Learn to implement key mitigations and detections for the attacks demonstrated.
You Should Know:
1. Initial Enumeration with NetExec
Gathering initial reconnaissance data is the first step in assessing an AD environment. NetExec is a powerful tool for network enumeration and exploitation.
`nxc smb 192.168.1.0/24 –local-auth -u ” -p ” –shares`
Step-by-step guide:
This command uses NetExec (nxc) to scan the `192.168.1.0/24` subnet for SMB services. The `–local-auth` flag attempts local authentication, and `-u ” -p ”` specifies blank username and password credentials, which often yields access on misconfigured systems. The `–shares` argument lists all available SMB shares on discovered hosts. Analyze the output for writable shares, like `NETLOGON` or SYSVOL, which can be used for initial foothold or data harvesting.
2. User Enumeration via LDAP
Identifying valid domain users is crucial for launching password attacks.
`nxc ldap 192.168.1.10 -u ‘guest’ -p ” –users`
Step-by-step guide:
This command targets the domain controller at `192.168.1.10` over the LDAP protocol. Using the supplied `guest` credentials (which often have minimal privileges but can still enumerate users), the `–users` flag instructs NetExec to query the domain and extract a complete list of domain users. This list becomes the basis for password spraying or brute-force attacks.
3. AS-REP Roasting Attack
Kerberos pre-authentication weaknesses can be exploited to harvest crackable user passwords.
`GetNPUsers.py DOMAIN.LOCAL/ -usersfile userlist.txt -format hashcat -output hashes.asreproast`
Step-by-step guide:
This Impacket script queries the Key Distribution Center (KDC) for users who have “Do not require Kerberos pre-authentication” set. The `-usersfile` flag provides a list of users to check. If vulnerable users are found, their encrypted AS-REP response is dumped in a format (-format hashcat) suitable for offline cracking with tools like Hashcat. The hashes are saved to `hashes.asreproast` for later analysis.
4. SMB Relay Attack with ntlmrelayx
Abusing the NTLM authentication protocol to relay credentials to target machines.
`ntlmrelayx.py -tf targets.txt -smb2support`
Step-by-step guide:
This Impacket script sets up an SMB relay server. The `-tf` flag points to a `targets.txt` file containing IP addresses of machines to relay credentials to. The `-smb2support` enables support for the newer SMB2 protocol. When an attacker tricks a user (e.g., via a phishing link) into authenticating to this relay server, the user’s NTLM credentials are relayed to the targets, potentially granting command execution if the user has administrative privileges on them.
5. Dumping Secrets with secretsdump.py
Extracting NTLM hashes and other secrets from a compromised host is a primary goal.
`secretsdump.py ‘DOMAIN.LOCAL/Jane.Doe:[email protected]’`
Step-by-step guide:
This powerful Impacket script remotely dumps SAM database hashes, LSA secrets, and cached domain credentials from the target machine (10.10.10.15). By providing a valid user’s credentials in the format domain/user:password@IP, the script authenticates and retrieves all stored secrets. The output will include NTLM hashes for local and domain users, which can be used for Pass-the-Hash attacks or cracked offline.
6. Pass-the-Hash for Lateral Movement
Using a compromised user’s NTLM hash to authenticate to other systems.
`nxc smb 192.168.1.20 -u ‘svc_sql’ -H ‘aad3b435b51404eeaad3b435b51404ee:579da618cfbfa85247acf1f800a280a4’ -x “whoami”`
Step-by-step guide:
This NetExec command uses Pass-the-Hash (PtH) to authenticate to the host 192.168.1.20. The `-H` flag provides the user’s NTLM hash instead of a password. The `-x` flag executes a specified command on the remote host (whoami in this case) to confirm access and identity. This technique bypasses the need to know the user’s plaintext password.
7. Golden Ticket Attack with mimikatz
Forging Kerberos tickets to achieve persistent domain administrator access.
`kerberos::golden /user:Administrator /domain:domain.local /sid:S-1-5-21-… /krbtgt:krbtgt_ntlm_hash /ptt`
Step-by-step guide:
Executed from the mimikatz tool, this command forges a “Golden Ticket.” The `/user` and `/domain` parameters define the fake ticket’s properties. The `/sid` is the domain’s security identifier, and `/krbtgt` is the hash of the KRBTGT account’s password, which must be previously obtained. The `/ptt` (Pass-the-Ticket) instruction injects the forged ticket directly into the current session’s memory, granting instant domain-wide administrative access.
What Undercode Say:
- Assumed Breach is the New Standard: The ease of techniques like AS-REP roasting and PtH demonstrates that credential compromise is often inevitable. Security strategies must pivot from pure prevention to robust detection and response, focusing on lateral movement and privilege escalation paths.
- The Power of Automation: Attackers use tools like NetExec and Impacket to automate exploitation at scale. Defenders must leverage similar automation for continuous security validation, using attack simulations to constantly test and improve their defensive controls.
The TCM Security course notes provide a brutally practical view of AD vulnerabilities, highlighting that misconfigurations, not zero-days, are the most common cause of domain compromise. The key insight for defenders is to master the attacker’s playbook. Understanding exactly how tools like mimikatz and Impacket work is not just for red teams; it is fundamental for blue teams to build effective hunting queries, configure meaningful alerts, and ultimately disrupt the attack chain before critical assets are breached.
Prediction:
The automation and weaponization of AD penetration testing techniques will continue to accelerate, lowering the barrier to entry for less sophisticated attackers. This will make ransomware and extortion attacks even more pervasive. In response, the industry will see a major shift towards stricter default configurations, the widespread adoption of Managed Service Accounts (gMSAs), and passwordless authentication technologies like Windows Hello for Business and FIDO2 keys to mitigate the primary attack vectors of credential theft and relay.
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IT/Security Reporter URL:
Reported By: https://lnkd.in/p/dt6D2Nrj – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
