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https://github.com/mandiant/capa.git
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112 lines
3.3 KiB
Python
112 lines
3.3 KiB
Python
import sys
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import logging
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import argparse
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import capa.main
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import capa.rules
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import capa.engine as ceng
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logger = logging.getLogger("detect_duplicate_features")
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def get_child_features(feature: ceng.Statement) -> list:
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"""
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Recursively extracts all feature statements from a given rule statement.
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Args:
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feature (capa.engine.Statement): The feature statement to extract features from.
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Returns:
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list: A list of all feature statements contained within the given feature statement.
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"""
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children = []
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if isinstance(feature, (ceng.And, ceng.Or, ceng.Some)):
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for child in feature.children:
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children.extend(get_child_features(child))
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elif isinstance(feature, (ceng.Subscope, ceng.Range, ceng.Not)):
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children.extend(get_child_features(feature.child))
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else:
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children.append(feature)
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return children
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def get_features(rule_path: str) -> list:
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"""
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Extracts all features from a given rule file.
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Args:
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rule_path (str): The path to the rule file to extract features from.
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Returns:
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list: A list of all feature statements contained within the rule file.
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"""
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feature_list = []
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with open(rule_path, "r", encoding="utf-8") as f:
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try:
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new_rule = capa.rules.Rule.from_yaml(f.read())
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feature_list = get_child_features(new_rule.statement)
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except Exception as e:
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logger.error("Error: New rule %s %s %s", rule_path, str(type(e)), str(e))
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sys.exit(-1)
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return feature_list
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def find_overlapping_rules(new_rule_path, rules_path):
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if not new_rule_path.endswith(".yml"):
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logger.error("FileNotFoundError ! New rule file name doesn't end with .yml")
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sys.exit(-1)
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# Loads features of new rule in a list.
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new_rule_features = get_features(new_rule_path)
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count = 0
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overlapping_rules = []
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# capa.rules.RuleSet stores all rules in given paths
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ruleset = capa.main.get_rules(rules_path)
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for rule_name, rule in ruleset.rules.items():
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rule_features = get_child_features(rule.statement)
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if not len(rule_features):
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continue
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count += 1
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# Checks if any features match between existing and new rule.
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if any(feature in rule_features for feature in new_rule_features):
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overlapping_rules.append(rule_name)
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result = {"overlapping_rules": overlapping_rules, "count": count}
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return result
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def main():
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parser = argparse.ArgumentParser(description="Find overlapping features in Capa rules.")
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parser.add_argument("rules", type=str, action="append", help="Path to rules")
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parser.add_argument("new_rule", type=str, help="Path to new rule")
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args = parser.parse_args()
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new_rule_path = args.new_rule
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rules_path = args.rules
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result = find_overlapping_rules(new_rule_path, rules_path)
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print("\nNew rule path : %s" % new_rule_path)
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print("Number of rules checked : %s " % result["count"])
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if result["overlapping_rules"]:
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print("Paths to overlapping rules : ")
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for r in result["overlapping_rules"]:
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print("- %s" % r)
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else:
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print("Paths to overlapping rules : None")
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print("Number of rules containing same features : %s" % len(result["overlapping_rules"]))
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print("\n")
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return len(result["overlapping_rules"])
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if __name__ == "__main__":
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sys.exit(main())
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