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Implement Include Callback for YARA Rule Includes #243

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Implement Include Callback for YARA Rule Includes #243

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3dd0193
update loki to support yara includes
spmaris Oct 29, 2023
2c84e7b
Update loki.py
spmaris Oct 29, 2023
d29c006
fixed an issue with the new function
spmaris Oct 29, 2023
d07136e
Merge branch 'Neo23x0:master' into master
spmaris Oct 29, 2023
7e6eba1
Merge branch 'master' into master
Neo23x0 Nov 25, 2024
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5 changes: 5 additions & 0 deletions lib/helpers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,11 @@ def is_cidr(string):
except:
return False

def recursive_file_search(directory, filename):
for root, dirs, files in os.walk(directory):
if filename in files:
return os.path.join(root, filename)
return None

def ip_in_net(ip, network):
try:
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94 changes: 68 additions & 26 deletions loki.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1100,6 +1100,30 @@ def initialize_filename_iocs(self, ioc_directory):
"See https://github.com/Neo23x0/Loki/issues/51")
sys.exit(1)

def include_callback(self, requested_filename, filename, namespace):
logger.log("DEBUG", "Init", f"Requested include: {requested_filename}")
try:
for yara_rule_directory in self.yara_rule_directories:
# Check in the current directory
possible_path = os.path.join(yara_rule_directory, requested_filename)
if os.path.exists(possible_path):
with open(possible_path, 'r') as file:
logger.log("DEBUG", "Init", f"Found include at: {possible_path}")
return file.read()

# Check in the possible subdirectory paths
possible_paths = recursive_file_search(yara_rule_directory, requested_filename)
if os.path.exists(possible_paths):
with open(possible_paths, 'r') as file:
logger.log("DEBUG", "Init", f"Found include at: {possible_paths}")
return file.read()

# Log an error if the included file is not found
logger.log("ERROR", "Init", f"Included file {requested_filename} not found in specified directories")

except Exception as e:
logger.log("ERROR", "Init", "Error finding include file: %s" % requested_filename)

def initialize_yara_rules(self):

yaraRules = ""
Expand All @@ -1110,7 +1134,8 @@ def initialize_yara_rules(self):
for yara_rule_directory in self.yara_rule_directories:
if not os.path.exists(yara_rule_directory):
continue
logger.log("INFO", "Init", "Processing YARA rules folder {0}".format(yara_rule_directory))
logger.log("INFO", "Init", "Processing YARA rules folder {0}".format(
yara_rule_directory))
for root, directories, files in os.walk(yara_rule_directory, onerror=walk_error, followlinks=False):
for file in files:
try:
Expand All @@ -1132,19 +1157,28 @@ def initialize_yara_rules(self):
yara_rule_data = yfile.read()

# Test Compile
# Test Compile
try:
compiledRules = yara.compile(source=yara_rule_data, externals={
'filename': dummy,
'filepath': dummy,
'extension': dummy,
'filetype': dummy,
'md5': dummy,
'owner': dummy,
})
logger.log("DEBUG", "Init", "Initializing Yara rule %s" % file)
compiledRules = yara.compile(
filepath=os.path.abspath(yaraRuleFile), # Use the absolute path
include_callback=self.include_callback,
includes=True,
externals={
'filename': dummy,
'filepath': dummy,
'extension': dummy,
'filetype': dummy,
'md5': dummy,
'owner': dummy,
}
)
logger.log("DEBUG", "Init",
"Initializing Yara rule %s" % file)
rule_count += 1
except Exception:
logger.log("ERROR", "Init", "Error while initializing Yara rule %s ERROR: %s" % (file, sys.exc_info()[1]))

except Exception as e:
logger.log("ERROR", "Init", "Error while initializing Yara rule %s ERROR: %s" % (
file, sys.exc_info()[1]))
traceback.print_exc()
if logger.debug:
sys.exit(1)
Expand All @@ -1153,27 +1187,35 @@ def initialize_yara_rules(self):
# Add the rule
yaraRules += yara_rule_data

except Exception:
logger.log("ERROR", "Init", "Error reading signature file %s ERROR: %s" % (yaraRuleFile, sys.exc_info()[1]))
except Exception as e:
logger.log("ERROR", "Init", "Error reading signature file %s ERROR: %s" % (
yaraRuleFile, sys.exc_info()[1]))
if logger.debug:
traceback.print_exc()
# sys.exit(1)

# Compile
try:
logger.log("INFO", "Init", "Initializing all YARA rules at once (composed string of all rule files)")
compiledRules = yara.compile(source=yaraRules, externals={
'filename': dummy,
'filepath': dummy,
'extension': dummy,
'filetype': dummy,
'md5': dummy,
'owner': dummy,
})
logger.log("INFO", "Init", "Initialized %d Yara rules" % rule_count)
except Exception:
logger.log(
"INFO", "Init", "Initializing all YARA rules at once (composed string of all rule files)")
compiledRules = yara.compile(
filepath=os.path.abspath(yaraRuleFile), # Use the absolute path
include_callback=self.include_callback,
includes=True,
externals={
'filename': dummy,
'filepath': dummy,
'extension': dummy,
'filetype': dummy,
'md5': dummy,
'owner': dummy,
})
logger.log("INFO", "Init",
"Initialized %d Yara rules" % rule_count)
except Exception as e:
traceback.print_exc()
logger.log("ERROR", "Init", "Error during YARA rule compilation ERROR: %s - please fix the issue in the rule set" % sys.exc_info()[1])
logger.log(
"ERROR", "Init", "Error during YARA rule compilation ERROR: %s - please fix the issue in the rule set" % sys.exc_info()[1])
sys.exit(1)

# Add as Lokis YARA rules
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