misp-modules/misp_modules/modules/expansion/yara_query.py

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import json
import re
try:
import yara
except (OSError, ImportError):
print("yara is missing, use 'pip3 install -I -r REQUIREMENTS' from the root of this repository to install it.")
misperrors = {'error': 'Error'}
moduleinfo = {'version': '1', 'author': 'Christian STUDER',
'description': 'Yara export for hashes.',
'module-type': ['expansion', 'hover'],
'require_standard_format': True}
moduleconfig = []
mispattributes = {'input': ['md5', 'sha1', 'sha256', 'filename|md5', 'filename|sha1', 'filename|sha256', 'imphash'], 'output': ['yara']}
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def extract_input_attribute(request):
for input_type in mispattributes['input']:
if input_type in request:
return input_type, request[input_type]
def get_hash_condition(hashtype, hashvalue):
hashvalue = hashvalue.lower()
required_module, params = ('pe', '()') if hashtype == 'imphash' else ('hash', '(0, filesize)')
return '{}.{}{} == "{}"'.format(required_module, hashtype, params, hashvalue), required_module
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def handler(q=False):
if q is False:
return False
request = json.loads(q)
attribute = extract_input_attribute(request)
if attribute is None:
return {'error': f'Wrong input type, please choose in the following: {", ".join(mispattributes["input"])}'}
uuid = request.pop('attribute_uuid') if 'attribute_uuid' in request else None
attribute_type, value = attribute
if 'filename' in attribute_type:
_, attribute_type = attribute_type.split('|')
_, value = value.split('|')
condition, required_module = get_hash_condition(attribute_type, value)
import_section = 'import "{}"'.format(required_module)
rule_start = '%s\r\nrule %s_%s {' % (import_section, attribute_type.upper(), re.sub(r'\W+', '_', uuid)) if uuid else '%s\r\nrule %s {' % (import_section, attribute_type.upper())
condition = '\tcondition:\r\n\t\t{}'.format(condition)
rule = '\r\n'.join([rule_start, condition, '}'])
try:
yara.compile(source=rule)
except Exception as e:
misperrors['error'] = 'Syntax error: {}'.format(e)
return misperrors
return {'results': [{'types': mispattributes['output'], 'values': rule}]}
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def introspection():
return mispattributes
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def version():
moduleinfo['config'] = moduleconfig
return moduleinfo