https://github.com/plyara/plyara

Parse YARA rules and operate over them more easily.
https://github.com/plyara/plyara

lexer parser ply python python3 sly yara yara-parser yara-rules

Last synced: 3 months ago
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Parse YARA rules and operate over them more easily.

• Host: GitHub
• URL: https://github.com/plyara/plyara
• Owner: plyara
• License: apache-2.0
• Created: 2018-06-05T00:53:20.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2024-06-24T18:34:27.000Z (5 months ago)
• Last Synced: 2024-07-18T19:13:55.062Z (4 months ago)
• Topics: lexer, parser, ply, python, python3, sly, yara, yara-parser, yara-rules
• Language: Python
• Homepage: https://plyara.readthedocs.io/
• Size: 481 KB
• Stars: 172
• Watchers: 11
• Forks: 37
• Open Issues: 23
• Metadata Files:
  • Readme: README.rst
  • License: LICENSE

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README

        
plyara

======

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Parse YARA_ rules into a dictionary representation.

Plyara is a script and library that lexes and parses a file consisting of one more YARA rules

into a python dictionary representation. The goal of this tool is to make it easier to perform

bulk operations or transformations of large sets of YARA rules, such as extracting indicators,

updating attributes, and analyzing a corpus. Other applications include linters and dependency

checkers.

Plyara leverages the Python module PLY_ for lexing YARA rules.

This is a community-maintained fork of the `original plyara`_ by 8u1a_. The "plyara" trademark

is used with permission.

Installation

------------

Plyara requires Python 3.6+.

Install with pip::

    pip3 install plyara

Usage

-----

Use the plyara Python library in your own applications:

.. code-block:: python

    >>> import plyara

    >>> parser = plyara.Plyara()

    >>> mylist = parser.parse_string('rule MyRule { strings: $a="1" \n condition: false }')

    >>>

    >>> import pprint

    >>> pprint.pprint(mylist)

    [{'condition_terms': ['false'],

      'raw_condition': 'condition: false ',

      'raw_strings': 'strings: $a="1" \n ',

      'rule_name': 'MyRule',

      'start_line': 1,

      'stop_line': 2,

      'strings': [{'name': '$a', 'type': 'text', 'value': '1'}]}]

    >>>

Or, use the included ``plyara`` script from the command line::

    $ plyara -h

    usage: plyara [-h] [--log] FILE

    Parse YARA rules into a dictionary representation.

    positional arguments:

      FILE        File containing YARA rules to parse.

    optional arguments:

      -h, --help  show this help message and exit

      --log       Enable debug logging to the console.

The command-line tool will print valid JSON output when parsing rules::

    $ cat example.yar

    rule silent_banker : banker

    {

        meta:

            description = "This is just an example"

            thread_level = 3

            in_the_wild = true

        strings:

            $a = {6A 40 68 00 30 00 00 6A 14 8D 91}

            $b = {8D 4D B0 2B C1 83 C0 27 99 6A 4E 59 F7 F9}

            $c = "UVODFRYSIHLNWPEJXQZAKCBGMT"

        condition:

            $a or $b or $c

    }

    $ plyara example.yar

    [

        {

            "condition_terms": [

                "$a",

                "or",

                "$b",

                "or",

                "$c"

            ],

            "metadata": [

                {

                    "description": "This is just an example"

                },

                {

                    "thread_level": 3

                },

                {

                    "in_the_wild": true

                }

            ],

            "raw_condition": "condition:\n        $a or $b or $c\n",

            "raw_meta": "meta:\n        description = \"This is just an example\"\n        thread_level = 3\n        in_the_wild = true\n    ",

            "raw_strings": "strings:\n        $a = {6A 40 68 00 30 00 00 6A 14 8D 91}\n        $b = {8D 4D B0 2B C1 83 C0 27 99 6A 4E 59 F7 F9}\n        $c = \"UVODFRYSIHLNWPEJXQZAKCBGMT\"\n    ",

            "rule_name": "silent_banker",

            "start_line": 1,

            "stop_line": 13,

            "strings": [

                {

                    "name": "$a",

                    "type": "byte",

                    "value": "{6A 40 68 00 30 00 00 6A 14 8D 91}"

                },

                {

                    "name": "$b",

                    "type": "byte",

                    "value": "{8D 4D B0 2B C1 83 C0 27 99 6A 4E 59 F7 F9}"

                },

                {

                    "name": "$c",

                    "type": "text",

                    "value": "UVODFRYSIHLNWPEJXQZAKCBGMT"

                }

            ],

            "tags": [

                "banker"

            ]

        }

    ]

Reusing The Parser

------------------

If you want to reuse a single instance of the parser object for efficiency when

parsing large quantities of rule or rulesets, the new clear() method must be

used.

.. code-block:: python

    rules = list()

    parser = plyara.Plyara()

    for file in files:

        with open(file, 'r') as fh:

            yararules = parser.parse_string(fh.read())

            rules += yararules

        parser.clear()

Migration

---------

If you used an older version of plyara, and want to migrate to this version,

there will be some changes required. Most importantly, the parser object

instantiation has changed. It was:

.. code-block:: python

    # Old style - don't do this!

    import plyara.interp as interp

    rules_list = interp.parseString(open('myfile.yar').read())

But is now:

.. code-block:: python

    # New style - do this instead!

    import plyara

    parser = plyara.Plyara()

    rules_list = parser.parse_string(open('myfile.yar').read())

The existing parsed keys have stayed the same, and new ones have been added.

When reusing a ``parser`` for multiple rules and/or files, be aware that

imports are now shared across all rules - if one rule has an import, that

import will be added to all rules in your parser object.

Contributing

------------

* If you find a bug, or would like to see a new feature, Pull Requests and

  Issues_ are always welcome.

* By submitting changes, you agree to release those changes under the terms

  of the LICENSE_.

* Writing passing unit tests for your changes, while not required, is highly

  encouraged and appreciated.

* Please run all code contributions through each of the linters that we use

  for this project: pycodestyle, pydocstyle, and pyflakes.  See the

  .travis.yml file for exact use.  For more information on these linters,

  please refer to the Python Code Quality Authority:

  http://meta.pycqa.org/en/latest/

Discussion

------------

* You may join our IRC channel on irc.freenode.net #plyara

.. _PLY: http://www.dabeaz.com/ply/

.. _YARA: http://plusvic.github.io/yara/

.. _plyara.readthedocs.io: https://plyara.readthedocs.io/en/latest/

.. _original plyara: https://github.com/8u1a/plyara

.. _8u1a: https://github.com/8u1a

.. _Issues: https://github.com/plyara/plyara/issues

.. _LICENSE: https://github.com/plyara/plyara/blob/master/LICENSE