Awesome

Padantic

Fast as fuck CLI tool for exploiting ALL sorts of padding oracles.

Optimizations

• Block level multithreading
• Guesses follow a priority list which is initialized to english letter frequencies and automatically readjusted as new bytes get found
• Last PAD bytes take a maximum of BLOCKSIZE tries

Usage

The oracle - in this case - is actually a command you supply, which takes the base64 encoded block via stdin and writes yes (correct padding)/no (incorrect padding) to stdout. You can find an example python oracle in python example. Oracles can be written in any language (or just make a shell script). The full oracle command line will get executed so feel free pass command line options.

usual usage:

padantic [hex encoded ciphertext] -O out -- python oracle.py

example usage:

padantic 4B730C0BC9F1FCA944D50B012DCDCDCD58D0BADA3B0CDADD849EFFB5351B1EE55A1D168B337089F5A88E43D4A7F403C5E527F9CAF5825A88B3E4EC72A2FEE1230FA71DA08C71ACB58D663679E265213567341CA9918AA14A8D6983D65C39E463560859BFA290DAFC419679CCA9688A7EF377E5E095B1D5876A50E90EB7DA9487CB8C141F15AF61431E3DB139DF3D8370 -O out -- python oracle.py

Command line Arguments:

padantic 0.1.0
catnip <catnip@catnip.fyi>


USAGE:
    padantic [FLAGS] [OPTIONS] <cipher> <oracle>...

FLAGS:
    -h, --help       
            Prints help information

    -v               
            use multiple times to increase log level. ex: -vv for `info`. 1 is the default so errors are always logged

        --noiv       
            skip CBC on first block and guess IV interactively

    -V, --version    
            Prints version information


OPTIONS:
        --chars <chars>      
            (space seperated) list of hex encoded bytes to guess the plaintext. ALL 256 POSSIBLE BYTES MUST BE PRESENT
            in no particular order. example: 00 01 02 ... 61 62 63 ... 6A 6B ... FF FF [default: english.chars]
        --log <log>          
            target file for logging output. log will contain stderr output from the oracle.

    -O, --output <output>    
            writes result to file

    -s, --size <size>        
            CBC block size [default: 16]


ARGS:
    <cipher>       
            target ciphertext (hex encoded)

    <oracle>...    
            the command to run as an oracle. should only return status 0 for valid padding. command will be ran with
            base64 paylod as first arg. arguments after cmd argument will be prepended BEFORE payload

Installation

cargo install padantic

To run it you must have the cargo bin directory in your path (recommended) or write

cargo run padantic

instead of just padantic

Look how pretty it looks

I'll need to update this gif someday since ive added colors to padantic but anyways, enjoy this gif:

Tricks

• The -noiv tags gets you the first blocks intermediate bytes so you can recover the IV if you guess the first blocks plaintext by simple XOR'ing them
• Consider adding a random delay (and useragent) to your oracle
• The -O tag is optional but its very usefull to have the results stored in a file
• If you need to debug your oracle, write to stderr and use the --log switch to generate a logfile. The logfile will contain every stderr output