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Simple python script for merging malware yara rules from https://github.com/Yara-Rules/rules
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#!/usr/bin/env python | |
# encoding: utf-8 | |
import os | |
import shutil | |
def get_rules_from_git(): | |
shutil.rmtree("./rules") | |
os.system("git clone https://github.com/Yara-Rules/rules.git") | |
def list_yara_files(): | |
all_yara_files = [] | |
for root, directories, filenames in os.walk("./rules/malware"): | |
print ("Processing " + root) | |
filenames.sort() | |
for file_name in filenames: | |
rule_filename, rule_file_extension = os.path.splitext(file_name) | |
if rule_file_extension == ".yar" or rule_file_extension == ".yara": | |
all_yara_files.append(os.path.join(root, file_name)) | |
return all_yara_files | |
def remove_incompatible_imports(files): | |
filtered_files = [] | |
for yara_file in files: | |
with open(yara_file, 'r') as fd: | |
yara_in_file = fd.read() | |
if not (("import \"math\"" in yara_in_file) or ("import \"cuckoo\"" in yara_in_file) or ("import \"hash\"" in yara_in_file) or ("imphash" in yara_in_file)): | |
filtered_files.append(yara_file) | |
return filtered_files | |
def fix_duplicated_rules(files): | |
filtered_files = [] | |
first_elf = True | |
to_delete = False | |
for yara_file in files: | |
print ("Processing " + yara_file) | |
with open(yara_file, 'r') as fd: | |
yara_in_file = fd.readlines() | |
for line in yara_in_file: | |
if line.strip() == "private rule is__elf {": | |
if first_elf: | |
first_elf = False | |
else: | |
to_delete = True | |
if not to_delete: | |
filtered_files.append(line) | |
if (not first_elf) and line.strip() == "}": | |
to_delete = False | |
filtered_files.append("\n") | |
return filtered_files | |
def merge_rules(all_rules): | |
with open("malware_rules.yar", 'w') as fd: | |
fd.write(''.join(all_rules)) | |
def main(): | |
get_rules_from_git() | |
all_yara_files = list_yara_files() | |
all_yara_filtered_1 = remove_incompatible_imports(all_yara_files) | |
all_yara_filtered_2 = fix_duplicated_rules(all_yara_filtered_1) | |
merge_rules(all_yara_filtered_2) | |
# Main body | |
if __name__ == '__main__': | |
main() |
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