There is a exploitable backend and an exploit script
git clone https://gitlab.com/kmille/padding-oracle.git
python -m virtualenv -p python2 venv
source venv/bin/activate
cd padding-oracle
pip install -r requirements.txt
# Run the backend
source venv/bin/activate
gunicorn --bind 127.0.0.1:5000 backend:app
# Run the backend script in a new tab
source venv/bin/activate
cd padding-oracle
python exploit_backend.py # for more debug output disable some comments in oracle.Oracle.solve_oracleGet the encrypted message IV: 7468697373686f756c646265726e646d Cipher: 4eff7c78220e0a1d63439eb7707c2583d1acf7be521e2cdb7dcdd77e22676481 Let the backend decrypt the message for testing Die ist ein beta Test Ciphertext in hex(64): 4eff7c78220e0a1d63439eb7707c2583d1acf7be521e2cdb7dcdd77e22676481 Ciphertext Blocks in hex: [u'4eff7c78220e0a1d63439eb7707c2583', u'd1acf7be521e2cdb7dcdd77e22676481'] Block counter: 1 Processing block #1: d1acf7be521e2cdb7dcdd77e22676481 Round counter: 0 Got no Padding Error for guess 0x89 Got intermediate byte #16: 88 All intermediates for this block: 88 Round counter: 1 Got no Padding Error for guess 0x2c Got intermediate byte #15: 2e All intermediates for this block: 882e Round counter: 2 Got no Padding Error for guess 0x74 Got intermediate byte #14: 77 All intermediates for this block: 882e77 Round counter: 3 Got no Padding Error for guess 0x7f Got intermediate byte #13: 7b All intermediates for this block: 882e777b Round counter: 4 Got no Padding Error for guess 0xb9 Got intermediate byte #12: bc All intermediates for this block: 882e777bbc Round counter: 5 Got no Padding Error for guess 0x93 Got intermediate byte #11: 95 All intermediates for this block: 882e777bbc95 Round counter: 6 Got no Padding Error for guess 0x4f Got intermediate byte #10: 48 All intermediates for this block: 882e777bbc9548 Round counter: 7 Got no Padding Error for guess 0x60 Got intermediate byte #9: 68 All intermediates for this block: 882e777bbc954868 Round counter: 8 Got no Padding Error for guess 0x1f Got intermediate byte #8: 16 All intermediates for this block: 882e777bbc95486816 Round counter: 9 Got no Padding Error for guess 0xb Got intermediate byte #7: 01 All intermediates for this block: 882e777bbc9548681601 Round counter: 10 Got no Padding Error for guess 0xe Got intermediate byte #6: 05 All intermediates for this block: 882e777bbc954868160105 Round counter: 11 Got no Padding Error for guess 0x5a Got intermediate byte #5: 56 All intermediates for this block: 882e777bbc95486816010556 Round counter: 12 Got no Padding Error for guess 0x6 Got intermediate byte #4: 0b All intermediates for this block: 882e777bbc954868160105560b Round counter: 13 Got no Padding Error for guess 0x17 Got intermediate byte #3: 19 All intermediates for this block: 882e777bbc954868160105560b19 Round counter: 14 Got no Padding Error for guess 0xa4 Got intermediate byte #2: ab All intermediates for this block: 882e777bbc954868160105560b19ab Round counter: 15 Got no Padding Error for guess 0x7e Got intermediate byte #1: 6e All intermediates for this block: 882e777bbc954868160105560b19ab6e Done with this round. Now XORING the intermediate bytes with the Cipher text of the previous ciphertext Cipher before in hex : 4eff7c78220e0a1d63439eb7707c2583 Recovered plain text: [' ', 'T', 'e', 's', 't', '\x0b', '\x0b', '\x0b', '\x0b', '\x0b', '\x0b', '\x0b', '\x0b', '\x0b', '\x0b', '\x0b'] Block counter: 0 Processing block #0: 4eff7c78220e0a1d63439eb7707c2583 Round counter: 0 Got no Padding Error for guess 0xd Got intermediate byte #16: 0c All intermediates for this block: 0c Round counter: 1 Got no Padding Error for guess 0x12 Got intermediate byte #15: 10 All intermediates for this block: 0c10 Round counter: 2 Got no Padding Error for guess 0x8 Got intermediate byte #14: 0b All intermediates for this block: 0c100b Round counter: 3 Got no Padding Error for guess 0x14 Got intermediate byte #13: 10 All intermediates for this block: 0c100b10 Round counter: 4 Got no Padding Error for guess 0x40 Got intermediate byte #12: 45 All intermediates for this block: 0c100b1045 Round counter: 5 Got no Padding Error for guess 0xa Got intermediate byte #11: 0c All intermediates for this block: 0c100b10450c Round counter: 6 Got no Padding Error for guess 0xa Got intermediate byte #10: 0d All intermediates for this block: 0c100b10450c0d Round counter: 7 Got no Padding Error for guess 0x1 Got intermediate byte #9: 09 All intermediates for this block: 0c100b10450c0d09 Round counter: 8 Got no Padding Error for guess 0x5c Got intermediate byte #8: 55 All intermediates for this block: 0c100b10450c0d0955 Round counter: 9 Got no Padding Error for guess 0x11 Got intermediate byte #7: 1b All intermediates for this block: 0c100b10450c0d09551b Round counter: 10 Got no Padding Error for guess 0x10 Got intermediate byte #6: 1b All intermediates for this block: 0c100b10450c0d09551b1b Round counter: 11 Got no Padding Error for guess 0x16 Got intermediate byte #5: 1a All intermediates for this block: 0c100b10450c0d09551b1b1a Round counter: 12 Got no Padding Error for guess 0x5e Got intermediate byte #4: 53 All intermediates for this block: 0c100b10450c0d09551b1b1a53 Round counter: 13 Got no Padding Error for guess 0x2 Got intermediate byte #3: 0c All intermediates for this block: 0c100b10450c0d09551b1b1a530c Round counter: 14 Got no Padding Error for guess 0xe Got intermediate byte #2: 01 All intermediates for this block: 0c100b10450c0d09551b1b1a530c01 Round counter: 15 Got no Padding Error for guess 0x20 Got intermediate byte #1: 30 All intermediates for this block: 0c100b10450c0d09551b1b1a530c0130 Done with this round. Now XORING the intermediate bytes with the Cipher text of the previous ciphertext Cipher before in hex : 7468697373686f756c646265726e646d Recovered plain text: ['D', 'i', 'e', ' ', 'i', 's', 't', ' ', 'e', 'i', 'n', ' ', 'b', 'e', 't', 'a'] Done Decrypted message: Die ist ein beta Test