binary-refinery 0.2.0

A toolkit to transform and refine (mostly) binary data.

Binary Refinery

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The Binary Refinery™ is a collection of Python scripts that implement transformations of binary data such as compression and encryption. We will often refer to it simply by refinery, which is also the name of the corresponding package. The scripts are designed to exclusively read input from stdin and write output to stdout. This way, the individual units can be chained with the piping operator | on the commandline to perform more complex tasks. The project was born to aid with malware triage, and is an attempt to implement something like CyberChef on the commandline.

The main philosophy of the refinery is that every script should be a unit in the sense that it does one job. It is always a case by case decision, but it is generally desirable to reduce the number of possible arguments of each script to a minimum and prefer strong capsulation if some functionality could be provided by a separate unit.

License

The Binary Refinery is (c) 2019 Jesko Hüttenhain, and published under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. This repository also contains a copy of the full license text. If you want to do something with it that's not covered by this license, please feel free to contact the author.

Installing the Refinery

The refinery requires at Python 3.7. Since binary refinery introduces a large number of new commands, there is a good chance that some of these will clash on some systems. Therefore, you have the option to choose a prefix for the installation, which will be put in front of every command shim that is installed. For example, if you choose r. as your prefix, then the emit command would be r.emit in your terminal. An added benefit is that you can type r. and hammer Tab twice to get a list of all available refinery commands.

Note however that no prefix is assumed in documentation and it is a development goal of refinery to not clash on most systems. The author does not use a prefix and provides this option as a safety blanket.

Automated Installation

You can either install refinery manually (see below) or use the automated installer script, which creates a virtual environment and installs the refinery package to that virtual environment. To do so, simply run setup-venv.py using the interpreter on your system which you would like to use for refinery. The script will create a virtual environment cloned from that interpreter version and install the binary refinery package into that virtual environment. On Windows, it also adds the Scripts directory of that virtual environment to your PATH, so all commands become available on the command line. The syntax for the script is as follows:

./setup-venv.py [--wheel] [--prefix pr] [folder]

The optional argument folder specifies the folder where the virtual Python environment is created, the default is venv. The optional value given by --prefix is the prefix (see above). Finally, the --wheel option will install the refinery package as a wheel, which may have some performance benefits. If this option is omitted, refinery is installed as an editable package, which means that any source code modifications in the repository will immediately take effect.

Some known issues arise when setup-venv.py is instructed to create the virtual environment in a location which already contains a virtual environment that was created by other means. As a workaround for these issues, don't do that, i.e. simply delete the virtual environment and use setup-venv.py to re-create it.

Manual Installation

To install refinery manually, simply set the environment variable REFINERY_PREFIX to the prefix you want and use pip. For example:

REFINERY_PREFIX=r. pip3 install -e binary-refinery

to install refinery into the current Python environment with prefix r..

Updating

To update refinery, it is sufficient to pull the repository and run setup-venv.py again with the same arguments after pulling the repository. If you installed refinery manually, you should first run pip uninstall binary-refinery and then install the package again. The uninstall is a safeguard to make sure that potentially deprecated command shims are removed before installing the new version. If you are using a virtual environment, you can always just remove the entire directory and install again, of course.

Generating Documentation

The documentation is available online, but you can also generate it locally. To do so, execute the run-pdoc3.py script. This will fail unless you run it from an environment where binary refinery has been installed as a Python package. To run it, you have to specify the path of a virtual environment as the first command line argument to run-pdoc3.py, which will cause the script to run itself again using the interpreter of that environment. If you are certain that you want to run run-pdoc3.py, there is a command line switch to force the script to run with the current default Python interpreter. The script installs the pdoc3 package and uses it to generate a HTML documentation for the refinery package. The documentation can then be found in the subdirectory html directly next to this readme file.

Simple Examples

The units emit and dump play a special role: The former is for outputting data while the latter is for dumping data to the clipboard or to disk. As an example, consider the following pipeline:

emit M7EwMzVzBkI3IwNTczM3cyMg2wQA | b64 | zl | hex 

Here, we emit the string M7EwMzVzBkI3IwNTczM3cyMg2wQA, base64-decode it using b64, zlib-decompress the result using zl, and finally hex-decode the decompressed data. Each unit performs the "decoding" operation of a certain transformation by default, but some of them also implement the reverse operation. If they do, this is always done by providing the command line switch -R, or --reverse. You can produce the above base64 string using the following command because hex, zl, and b64 all provide the reverse operation:

emit "Hello World" | hex -R | zl -R | b64 -R

Given a file packed.bin containing a base64 encoded payload buffer, the following pipeline extracts said payload to payload.bin:

emit packed.bin | carve -l -t1 b64 | b64 | dump payload.bin

The carve unit can be used to carve blocks of data out of the input buffer, in this case it looks for base64 encoded data, sorts them by length (-l) and returns the first of these (-t1), which carves the largest base64-looking chunk of data from packed.bin. The data is then base64-decoded and dumped to the file payload.bin.

The unit pack, will pick all numeric expressions from a text buffer and turn them into their binary representation. A simple example is the pipeline

emit "0xBA 0xAD 0xC0 0xFF 0xEE" | pack | hex -R 

which will output the string BAADC0FFEE.

Additional Information

A complete reference of all units is available on the front page of the documentation. It is recommended to study the documentation on the argument syntax as well as framed syntax to unleash the full power of the refinery.

Examples

AES Encryption

Assume that data is a file which was encrypted with 256 bit AES in CBC mode. The key was derived from the secret passphrase swordfish using the PBKDF2 key derivation routine using the salt s4lty. The IV is prefixed to the buffer as the first 16 bytes. It can be decrypted with the following pipeline:

emit data | aes CBC  --iv cut::16 PBKDF2[32,s4lty]:swordfish

Here, both cut:0:16 and PBKDF2[32,s4lty]:swordfish are multibin arguments that use a special handler. In this case, cut:0:16 extracts the slice 0:16 (i.e. the first 16 bytes) from the input data - after application of this multibin handler, the input data has the first 16 bytes removed and the argument iv is set to these exact 16 bytes. The final argument specifies the 32 byte encryption key: The handler PBKDF2[32,s4lty] on the other hand instructs refinery to create an instance of the PBKDF2 unit as if it had been given the command line parameters 32 and s4lty in this order and process the byte string swordfish with this unit. As a simple test, the following pipeline will encrypt and decrypt a sample piece of text:

emit "Once upon a time, at the foot of a great mountain ..." ^
    | aes CBC PBKDF2[32,s4lty]:swordfish --iv md5:X -R | ccp md5:X ^
    | aes CBC PBKDF2[32,s4lty]:swordfish --iv cut:0:16 

Grab Bag of Examples

Extract indicators from all files recursively enumerated inside the current directory:

fread ./**/* [| xtp -qn6 ipv4 socket url email | dedup ]]

Convert the hard-coded IP address 0xC0A80C2A in network byte order to a readable format:

emit 0xC0A80C2A | pack -EB4 | pack -R [| sep . ]

Extract the PowerShell payload from a malicious XLS macro dropper:

emit MIL0001781108.xls            \
[| xlxtr 9.5:11.5 15.15 12.5:14.5 \
 [| scope -n 3                    \
  | chop -t 5                     \
  [| sorted                       \
   | snip 2:                      \
   | sep                          \
  ]                               \
  | pack 10                       \
  | blockop --dec -sN B-S         \
]]                                \
| dump payload.ps1

And get the domains for the next stage:

emit payload.ps1 | carveb64z | deob-ps1 | carveb64z | deob-ps1 | xtp -f domain

Exctract the configuration of unpacked HawkEye samples:

emit 30ae8004a14f188d40c024124022d63d                \
| xtp guid                                           \
[| PBKDF2 48 rep[8]:H:00                             \
 | cca perc[RCDATA]:30ae8004a14f188d40c024124022d63d \
 | aes -Q CBC x::32 --iv x::16                       \
]                                                    \
| dnds