mirror of https://github.com/MISP/PyMISP
94 lines
3.3 KiB
Python
Executable File
94 lines
3.3 KiB
Python
Executable File
#!/usr/bin/env python3
|
|
# -*- coding: utf-8 -*-
|
|
'''
|
|
YARA dumper for MISP
|
|
by Christophe Vandeplas
|
|
'''
|
|
|
|
import keys
|
|
from pymisp import PyMISP
|
|
import yara
|
|
import re
|
|
|
|
|
|
def dirty_cleanup(value):
|
|
changed = False
|
|
substitutions = (('”', '"'),
|
|
('“', '"'),
|
|
('″', '"'),
|
|
('`', "'"),
|
|
('\r', '')
|
|
# ('$ ', '$'), # this breaks rules
|
|
# ('\t\t', '\n'), # this breaks rules
|
|
)
|
|
for substitution in substitutions:
|
|
if substitution[0] in value:
|
|
changed = True
|
|
value = value.replace(substitution[0], substitution[1])
|
|
return value, changed
|
|
|
|
|
|
misp = PyMISP(keys.misp_url, keys.misp_key, keys.misp_verify, 'json')
|
|
result = misp.search(controller='attributes', type_attribute='yara')
|
|
|
|
attr_cnt = 0
|
|
attr_cnt_invalid = 0
|
|
attr_cnt_duplicate = 0
|
|
attr_cnt_changed = 0
|
|
yara_rules = []
|
|
yara_rule_names = []
|
|
if 'response' in result and 'Attribute' in result['response']:
|
|
for attribute in result['response']['Attribute']:
|
|
value = attribute['value']
|
|
event_id = attribute['event_id']
|
|
attribute_id = attribute['id']
|
|
|
|
value = re.sub('^[ \t]*rule ', 'rule misp_e{}_'.format(event_id), value, flags=re.MULTILINE)
|
|
value, changed = dirty_cleanup(value)
|
|
if changed:
|
|
attr_cnt_changed += 1
|
|
if 'global rule' in value: # refuse any global rules as they might disable everything
|
|
continue
|
|
|
|
# compile the yara rule to confirm it's validity
|
|
# if valid, ignore duplicate rules
|
|
try:
|
|
attr_cnt += 1
|
|
yara.compile(source=value)
|
|
yara_rules.append(value)
|
|
# print("Rule e{} a{} OK".format(event_id, attribute_id))
|
|
except yara.SyntaxError as e:
|
|
attr_cnt_invalid += 1
|
|
# print("Rule e{} a{} NOK - {}".format(event_id, attribute_id, e))
|
|
except yara.Error as e:
|
|
attr_cnt_invalid += 1
|
|
print(e)
|
|
import traceback
|
|
print(traceback.format_exc())
|
|
|
|
# remove duplicates - process the full yara rule list and process errors to eliminate duplicate rule names
|
|
all_yara_rules = '\n'.join(yara_rules)
|
|
while True:
|
|
try:
|
|
yara.compile(source=all_yara_rules)
|
|
except yara.SyntaxError as e:
|
|
if 'duplicated identifier' in e.args[0]:
|
|
duplicate_rule_names = re.findall('duplicated identifier "(.*)"', e.args[0])
|
|
for item in duplicate_rule_names:
|
|
all_yara_rules = all_yara_rules.replace('rule {}'.format(item), 'rule duplicate_{}'.format(item), 1)
|
|
attr_cnt_duplicate += 1
|
|
continue
|
|
else:
|
|
# This should never happen as all rules were processed before separately. So logically we should only have duplicates.
|
|
exit("ERROR SyntaxError in rules: {}".format(e.args))
|
|
break
|
|
|
|
# save to a file
|
|
fname = 'misp.yara'
|
|
with open(fname, 'w') as f_out:
|
|
f_out.write(all_yara_rules)
|
|
|
|
print("")
|
|
print("MISP attributes with YARA rules: total={} valid={} invalid={} duplicate={} changed={}.".format(attr_cnt, attr_cnt - attr_cnt_invalid, attr_cnt_invalid, attr_cnt_duplicate, attr_cnt_changed))
|
|
print("Valid YARA rule file save to file '{}'. Invalid rules/attributes were ignored.".format(fname))
|