Proof of Concept

Overview

Vulnerability confirmed → Now achieve highest possible exploitation impact and automate it.

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PoC Phases

Full Chain Exploitation
         ↓
  Exploit Development
         ↓
 Test on Real Target

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Phase 1: Full Chain Exploitation

Goal

Document working exploitation process step-by-step.

What to Document

Element	Description
Initial target location	Entry point URL/endpoint
Client-side payload	First payload sent
Additional payloads	For chained vulnerabilities
Bypasses	WAF, filter, encoding bypasses

Process

1. Start from client-side input
         ↓
2. Document each payload needed
         ↓
3. If chaining vulns, document each step
         ↓
4. If blocked, work on bypass
         ↓
5. Proceed to next step
         ↓
6. Repeat until full exploitation

Chained Vulnerability Example

Step 1: SQLi to bypass authentication
   Payload: admin' OR '1'='1
   Result: Logged in as admin
         ↓
Step 2: File upload as admin
   Payload: shell.php.jpg with PHP content
   Bypass: Double extension
   Result: Shell uploaded
         ↓
Step 3: RCE via uploaded shell
   Location: /uploads/shell.php.jpg
   Payload: ?cmd=whoami
   Result: Command execution

Handling Blocks

Block	Action
WAF blocks payload	Research bypasses, encoding
Filter removes chars	Find alternative chars/encoding
Blind exploitation	Develop OOB or time-based
Rate limiting	Add delays, use multiple sessions

If Full Exploitation Fails

• Still report vulnerability

• Severity may be reduced

• Document what was achieved

• Note what prevented full exploitation

Tip: Persist! If you can't achieve full exploitation, someone else will with better bypasses or chained vulns.

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Phase 2: Exploit Development

Goal

Write script that automatically reproduces exploitation steps.

Language Selection

Use Case	Language	Reason
Network/Web applications	Python	Cross-platform, good libraries
Client-side (CSRF, etc.)	JavaScript	Only executes in browsers
Web + client-side chain	Python + JavaScript	JS for client, Python for backend
Binary exploitation	Python	Good debugging libraries (pwntools)
OS targeting	Bash/PowerShell	Pre-installed on target OS
Thick client/advanced	Application's language	Reuse code/functions

Python Exploit Structure

#!/usr/bin/env python3
import requests
import sys

class Exploit:
    def __init__(self, target, port):
        self.target = target
        self.port = port
        self.session = requests.Session()
    
    def check_vuln(self):
        """Verify target is vulnerable"""
        pass
    
    def stage1_auth_bypass(self):
        """First stage: bypass authentication"""
        pass
    
    def stage2_upload_shell(self):
        """Second stage: upload web shell"""
        pass
    
    def stage3_rce(self, cmd):
        """Third stage: execute commands"""
        pass
    
    def cleanup(self):
        """Remove traces of exploitation"""
        pass
    
    def run(self):
        """Main exploitation flow"""
        try:
            if not self.check_vuln():
                print("[-] Target not vulnerable")
                return False
            
            self.stage1_auth_bypass()
            self.stage2_upload_shell()
            self.stage3_rce("whoami")
            return True
        except Exception as e:
            print(f"[-] Error: {e}")
            self.cleanup()
            return False
        finally:
            self.cleanup()

if __name__ == "__main__":
    if len(sys.argv) != 3:
        print(f"Usage: {sys.argv[0]} <target> <port>")
        sys.exit(1)
    
    exploit = Exploit(sys.argv[1], int(sys.argv[2]))
    exploit.run()

Key Exploit Features

Feature	Purpose
Error handling	Graceful failure, cleanup on error
Cleanup function	Remove traces
Modular stages	Easy to debug/modify
Verification	Confirm target is vulnerable first
Configurability	Easy to change target

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Phase 3: Test on Real Target

Before Testing on Production

• Thoroughly tested on test environment

• All security mechanisms enabled during tests

• Works fully automatically

• Safe to run (no data loss/downtime)

Modifications for Production

# Change target details
TARGET = "production.target.com"  # Was: "test.local"
PORT = 443                        # Was: 8080
USE_HTTPS = True                  # Was: False

Safety Requirements

Requirement	Implementation
Revertible	Can undo all changes
Clean traces	Remove created files/accounts
Handle errors	Cleanup even on failure
Non-destructive	Never modify critical data
No downtime	Operations don't crash services

What to Clean Up

Action Taken	Cleanup Required
Created account	Delete account
Modified data	Reset to original
Uploaded files	Delete files
Changed configs	Restore configs
Created DB entries	Remove entries

Error Handling Pattern

def exploit(self):
    created_user = None
    uploaded_file = None
    
    try:
        # Stage 1
        created_user = self.create_user()
        
        # Stage 2
        uploaded_file = self.upload_shell()
        
        # Stage 3
        result = self.execute_command()
        
        return result
        
    except Exception as e:
        print(f"[-] Exploit failed: {e}")
        raise
        
    finally:
        # Always cleanup
        if uploaded_file:
            self.delete_file(uploaded_file)
        if created_user:
            self.delete_user(created_user)

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PoC Documentation Template

# Vulnerability: [Name]

## Summary
Brief description of the vulnerability.

## Affected Version
- Application: v1.2.3
- Component: /api/upload

## Prerequisites
- Valid user account
- Network access to target

## Exploitation Steps

### Step 1: Authentication Bypass
Payload: `admin' OR '1'='1`
Endpoint: POST /login

### Step 2: Shell Upload
Payload: [shell.php content]
Bypass: Double extension
Endpoint: POST /upload

### Step 3: RCE
Command: `whoami`
Endpoint: GET /uploads/shell.php.jpg?cmd=whoami

## Proof
[Screenshot or output]

## Remediation
[Recommended fix]

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Checklist

Full Chain Exploitation

• All steps documented

• All payloads recorded

• Bypasses identified and tested

• Can reproduce manually

Exploit Development

• Script automates all steps

• Error handling implemented

• Cleanup function works

• Tested on test environment

Production Testing

• Target details configured

• Safe to run verified

• Cleanup confirmed working

• Successful execution documented