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refactor: Simplifies project structure.
clava's structure has grown into quite a mess, mostly because most parts were created during researching this project. This commit attempts at restructuring major parts of clava without chaning much of the functionality. I've removed some of the features that I never used since early development, but they might re-appear in a more generalized form. Next step will be the migration of the logic burried in the Jupyter notebooks.
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@@ -38,8 +38,8 @@ | |
| extras_require={ | ||
| 'dev': [ | ||
| 'pytest', | ||
| 'pandas', | ||
| 'mypy' | ||
| 'mypy', | ||
| 'pandas', # TODO: Remove pandas dep | ||
| ] | ||
| } | ||
| ) | ||
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| @@ -1 +1 @@ | ||
| __version__ = 1.0 | ||
| __version__ = "1.0.0" |
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| @@ -1,167 +1,78 @@ | ||
| """clava v1.0 | ||
| Generate Code-Based Yara Rules. | ||
| """clava v1.0: Generate code-based Yara rules. | ||
| Usage: | ||
| clava_cli.py signature <file> [--n=<sequences>] [--strategy=<strategy>] | ||
| clava_cli.py yara <file> [--n=<sequences>] [--strategy=<strategy>] [--output=<output file>] | ||
| clava_cli.py dump <file> | ||
| clava_cli.py <file> [--topk=<sequences>] [--output=<output file>] | ||
| Options: | ||
| -h --help Show this message. | ||
| --version Show version of clava. | ||
| --n=<sequences> Size of the sequences [default: 3]. | ||
| --strategy=<strategy> Signature generator to use [default: logreg-tf]. | ||
| --topk=<sequences> Number of instruction sequences to use [default: 3] | ||
| --output=<output file> Store the generated rule in this file. | ||
| """ | ||
| import sys | ||
| import warnings | ||
| from operator import attrgetter | ||
| from pathlib import Path | ||
| from typing import Dict, Literal | ||
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| from docopt import docopt | ||
| from pefile import PEFormatError | ||
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| from clava.crafting import to_yara | ||
| from clava.generators.logregtf import LogRegTF | ||
| from clava.io import disassemble, disassembleX | ||
| from clava.models import Signature | ||
| from clava.disassembling import disassemble | ||
| from clava.inference import LogRegClassifier | ||
| from clava.output import generate_yara_rule | ||
|
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| # Suppress sklearn warnings for now (version mismatch) | ||
| warnings.filterwarnings("ignore", category=UserWarning) | ||
| NGRAM_SIZE = 6 | ||
| CLASSIFIER_PATH = Path('wipro/models/simple-tf-logreg/logregtf.joblib') | ||
| VECTORIZER_PATH = Path('wipro/models/simple-tf-logreg/tfvectorizer.joblib') | ||
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| def abort(msg): | ||
| print("ERROR:", msg, file=sys.stderr) | ||
| sys.exit(1) | ||
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| def input_file(filepath: str): | ||
| path_to_file = Path(filepath) | ||
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| if not path_to_file.exists(): | ||
| abort("No such file or directory: " + path_to_file.name) | ||
|
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| return path_to_file | ||
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| def generate_signature( | ||
| arguments: Dict, | ||
| signature_format: Literal['plain', 'yara'] | ||
| ): | ||
| def generate_signature(arguments): | ||
| """ | ||
| Generate a signature for the provided binary. | ||
| Currently, clava supports two signature formats: | ||
| * plain: Returns the internal representation of a signature, used for | ||
| debugging. | ||
| Generate Yara rule for a sample. | ||
| * yara: Returns a yara rule, which can be directly used with | ||
| the official yara binaries (or yarac for compilation) | ||
| Unless you are working on new models, you'll want 'yara'. | ||
| The generated yara rule can be directly used with the official yara binaries | ||
| (or yarac for compilation). | ||
| NOTE: At the moment, we only support signatures for Portable Executables | ||
| (PE) files. Other exectuable formats such as ELF are not supported, | ||
| but could be added easily. | ||
| """ | ||
| # Binary to create signature for | ||
| input_sample = input_file(arguments['<file>']) | ||
| sample = Path(arguments['<file>']) | ||
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|
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| # Store the resulting rule in this file (or write to stdout) | ||
| output_file = arguments.get('--output', None) | ||
| # How many sequences (i.e., opcode n-grams) to include in the signature | ||
| num_sequences_in_signatures = int(arguments.get('--n', 3)) | ||
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| print(f"[*] Creating signature for {input_sample.name} " | ||
| f"(with: n={num_sequences_in_signatures})") | ||
| # How many sequences (i.e., opcode n-grams) to include in the signature | ||
| num_sequences_in_signatures = int(arguments.get('--topk', 3)) | ||
|
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||
| try: | ||
| sample = disassembleX(Path(input_sample)) | ||
| mode, disassembly = disassemble(sample) | ||
| except PEFormatError: | ||
| abort(f"Sample '{input_sample.name}' is not a valid PE file.") | ||
| abort(f"Sample '{sample.name}' is not a valid PE file.") | ||
| except ValueError: | ||
| abort( | ||
| f"Unable to locate code section in sample: '{input_sample.name}'," | ||
| f"Unable to locate code section in sample: '{sample.name}'," | ||
| "might be obfuscated, packed or encrypted." | ||
| ) | ||
|
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||
| # TODO: Actually load the correct strategy from CLI arguments. | ||
| strategy = LogRegTF( | ||
| 'wipro/models/simple-tf-logreg/logregtf.joblib', | ||
| 'wipro/models/simple-tf-logreg/tfvectorizer.joblib', | ||
| num_sequences_in_signatures | ||
| ) | ||
|
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| # `generate` ranks all opcode sequences by their maliciousness and returns | ||
| # the top-k sequences, which we'll put 1:1 in a signature. | ||
| sequences = strategy.generate(sample, num_sequences_in_signatures) | ||
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| if signature_format == "yara": | ||
| # Format signature as a Yara rule | ||
| yara_rule_str = to_yara( | ||
| "clava_" + sample.filename, | ||
| sequences, | ||
| dict(architecture=sample.architecture) | ||
| ) | ||
| model = LogRegClassifier(CLASSIFIER_PATH, VECTORIZER_PATH, ngram_size=6) | ||
|
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| # Always display the generated rule | ||
| print(yara_rule_str) | ||
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| if output_file: | ||
| with open(output_file, 'w') as fd: | ||
| fd.write(yara_rule_str) | ||
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| print("[*] Yara Rule written to " + output_file) | ||
| elif signature_format == "plain": | ||
| # plain format is used during development and probably makes not much | ||
| # sense to anyone else. This format just outputs the sequence of | ||
| # mnemonics in the selected sequences, e.g., | ||
| # | ||
| # Signature( | ||
| # sequences=[ | ||
| # 'shl xor xor xor movabs and', | ||
| # 'shl lea movsxd shl lea test', | ||
| # 'lea shl xor xor xor movabs' | ||
| # ]) | ||
| topk_mnemonics = [] | ||
| for seq in sequences: | ||
| topk_mnemonics.append(" ".join(e.mnemonic for e in seq[1])) | ||
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| signature = Signature(topk_mnemonics) | ||
| print("[!] Got: ", signature) | ||
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| def dump(arguments): | ||
| """ | ||
| Dump the instructions of the passed binary. | ||
| """ | ||
| binary = input_file(arguments['<file>']) | ||
| sequences = model.rank(disassembly, topk=num_sequences_in_signatures) | ||
|
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| try: | ||
| _, instructions = disassemble( | ||
| binary, | ||
| decode=attrgetter('mnemonic') | ||
| ) | ||
| except PEFormatError: | ||
| abort(binary.name + " does not appear to be a valid PE file.") | ||
| yara_rule_str = generate_yara_rule("clava_" + sample.name, sequences, mode) | ||
|
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| print(yara_rule_str) | ||
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| print(f"{binary}: ({','.join(instructions)})") | ||
| if output_file: | ||
| Path(output_file).write_text(yara_rule_str) | ||
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| def main(): | ||
| arguments = docopt(__doc__, version="clava v1.0") | ||
|
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| if arguments['signature']: | ||
| generate_signature(arguments, "plain") | ||
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| if arguments['yara']: | ||
| generate_signature(arguments, "yara") | ||
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| elif arguments['dump']: | ||
| dump(arguments) | ||
|
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| if __name__ == "__main__": | ||
| main() | ||
| generate_signature(arguments) |
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