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yarAnalyzer.py
608 lines (486 loc) · 24.4 KB
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yarAnalyzer.py
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#!/usr/bin/env python
# -*- coding: iso-8859-1 -*-
# -*- coding: utf-8 -*-
"""
yarAnalyzer
Yara Rule Statistics and Analysis
Florian Roth
DISCLAIMER - USE AT YOUR OWN RISK.
"""
__version__ = "0.5"
import sys
import os
import argparse
import scandir
import traceback
import yara
import hashlib
import re
import stat
import datetime
import platform
import binascii
import shutil
from prettytable import PrettyTable
def scan_path(path, rule_sets, num_first_bytes=6):
# Startup
log("INFO","Scanning %s ... " % path)
# Counter
c = 0
# Get application path
app_path = get_application_path()
for root, directories, files in scandir.walk(path, onerror=walk_error, followlinks=False):
# Loop through files
for filename in files:
try:
# Get the file and path
filePath = os.path.join(root,filename)
# Relative Path
relPath = filePath[len(path):]
fileSize = os.stat(filePath).st_size
if fileSize > ( args.m * 1024 * 1024):
continue
# Prepare the file matches
file_stats[relPath] = {}
file_stats[relPath]["matches"] = {}
file_stats[relPath]["size"] = fileSize
# Set fileData to an empty value
fileData = ""
# Hash Check -------------------------------------------------------
# Do the check
md5 = "-"
sha1 = "-"
sha256 = "-"
fileData = read_file_data(filePath)
if len(fileData) > 1:
file_stats[relPath]["firstBytes_Hex"] = "%s" % fileData[:num_first_bytes].encode("hex")
file_stats[relPath]["firstBytes_Ascii"] = "%s" % remove_non_ascii(fileData[:num_first_bytes])
else:
file_stats[relPath]["firstBytes_Hex"] = "-"
file_stats[relPath]["firstBytes_Ascii"] = "-"
md5, sha1, sha256 = generate_hashes(fileData)
file_stats[relPath]["md5"] = md5
file_stats[relPath]["sha1"] = sha1
file_stats[relPath]["sha256"] = sha256
log("DEBUG", "MD5: %s SHA1: %s SHA256: %s FILE: %s" % ( md5, sha1, sha256, filePath ))
if args.printAll:
print "FILE: %s" % ( filePath )
# Yara Check -------------------------------------------------------
# Scan with yara
try:
for rules in rule_sets:
# Yara Rule Match -------------------------------------
matches = rules.match(data=fileData,
externals= {
'filename': filename.lower(),
'filepath': filePath.lower()
})
# If matched ------------------------------------------
if matches:
for match in matches:
description = "not set"
# Built-in rules have meta fields (cannot be expected from custom rules)
if hasattr(match, 'meta'):
if 'description' in match.meta:
description = match.meta['description']
# Matching strings
matched_strings = ""
if hasattr(match, 'strings'):
# Get matching strings
matched_strings = get_string_matches(match.strings)
# Add the stats
# File Stats
if relPath not in file_stats:
file_stats[relPath] = {}
if "matches" not in file_stats[relPath]:
file_stats[relPath]["matches"] = {}
file_stats[relPath]["matches"][match.rule] = matched_strings
# Rule Stats
if match.rule not in rule_stats:
rule_stats[match.rule] = {}
if "files" not in rule_stats[match.rule]:
rule_stats[match.rule]["files"] = []
rule_stats[match.rule]["files"].append(relPath)
except Exception, e:
if args.debug:
traceback.print_exc()
except Exception, e:
if args.debug:
traceback.print_exc()
def read_file_data(filePath):
fileData = ""
try:
# Read file complete
with open(filePath, 'rb') as f:
fileData = f.read()
except Exception, e:
log("DEBUG", "Cannot open file %s (access denied)" % filePath)
finally:
return fileData
def generate_hashes(filedata):
try:
md5 = hashlib.md5()
sha1 = hashlib.sha1()
sha256 = hashlib.sha256()
md5.update(filedata)
sha1.update(filedata)
sha256.update(filedata)
return md5.hexdigest(), sha1.hexdigest(), sha256.hexdigest()
except Exception, e:
traceback.print_exc()
return 0, 0, 0
def get_string_matches(strings):
try:
string_matches = []
matching_strings = ""
for string in strings:
# print string
extract = string[2]
if not extract in string_matches:
string_matches.append(extract)
string_num = 1
for string in string_matches:
# UNICDOE
if '\0' in string:
matching_strings += " Str" + str(string_num) + "(U): " + remove_non_ascii(remove_binary_zero(string))
else:
# ASCII
matching_strings += " Str" + str(string_num) + "(A): " + remove_non_ascii(remove_binary_zero(string))
string_num += 1
# Limit string
if len(matching_strings) > 140:
matching_strings = matching_strings[:140] + " ... (truncated)"
return matching_strings.lstrip(" ")
except:
traceback.print_exc()
def walk_error(err):
if "Error 3" in str(err):
log("ERROR", str(err))
if args.debug:
traceback.print_exc()
def initialize_yara_rules(rule_path, rules_extension):
yara_rule_infos = {}
yara_rules = []
dummy = ""
# Signature are located in a path
if os.path.isdir(rule_path):
try:
for root, directories, files in scandir.walk(rule_path, onerror=walk_error, followlinks=False):
for file in files:
try:
# Full Path
yaraRuleFile = os.path.join(root, file)
# Skip hidden, backup or system related files
if file.startswith(".") or file.startswith("~") or file.startswith("_"):
continue
# Extension
extension = os.path.splitext(file)[1].lower()
# Compile
if extension == ".{0}".format(rules_extension):
try:
compiledRules = yara.compile(yaraRuleFile, externals={
'filename': dummy,
'filepath': dummy,
'extension': dummy,
'filetype': dummy,
'id': dummy,
'md5': dummy,
})
# Yara Rule Info - used for inventory
for rule in compiledRules:
if file not in yara_rule_infos:
yara_rule_infos[file] = {}
if rule.identifier not in yara_rule_infos[file]:
yara_rule_infos[file][rule.identifier] = {}
if "description" in rule.meta:
yara_rule_infos[file][rule.identifier]["description"] = rule.meta["description"]
if "reference" in rule.meta:
yara_rule_infos[file][rule.identifier]["reference"] = rule.meta["reference"]
yara_rules.append(compiledRules)
log("INFO", "Initialized Yara rules from %s" % file)
except Exception, e:
log("ERROR", "Error in Yara file: %s" % file)
if args.debug:
traceback.print_exc()
except Exception, e:
log("ERROR", "Error reading signature file %s ERROR: %s" % yaraRuleFile)
if args.debug:
traceback.print_exc()
except Exception, e:
log("ERROR", "Error reading signature folder /signatures/")
if args.debug:
traceback.print_exc()
# Is a signature file
else:
try:
compiledRules = yara.compile(rule_path, externals= {
'filename': dummy,
'filepath': dummy
})
yara_rules.append(compiledRules)
log("INFO", "Initialized Yara rules from %s" % rule_path)
except Exception, e:
log("ERROR", "Error in Yara file: %s" % rule_path)
if args.debug:
traceback.print_exc()
return yara_rules, yara_rule_infos
def generate_yara_inventory(output_file, yara_rule_infos):
log("INFO", "Generating Inventory")
try:
with open(output_file, 'w') as output:
output.write("Rule File;Rule Name;Description;Reference;Compile Issue\n")
for rule_file in yara_rule_infos:
for rule_name in yara_rule_infos[rule_file]:
description = "-"
reference = "-"
if "description" in yara_rule_infos[rule_file][rule_name]:
description = yara_rule_infos[rule_file][rule_name]["description"]
if "reference" in yara_rule_infos[rule_file][rule_name]:
reference = yara_rule_infos[rule_file][rule_name]["reference"]
# Clean strings
description = description.replace("; ", " / ").replace(";", " ")
reference = reference.replace("; ", " / ").replace(";", " ")
output.write("{0};{1};{2};{3};\n".format(rule_file, rule_name, description, reference))
except Exception, e:
traceback.print_exc()
def generate_yara_stats_structure(yara_rules):
for rule_set in yara_rules:
for rule in rule_set:
rule_stats[rule.identifier] = {}
rule_stats[rule.identifier]["files"] = []
rule_stats[rule.identifier]["count"] = 0
def remove_binary_zero(string):
return re.sub(r'\x00','',string)
def get_application_path():
try:
application_path = ""
if getattr(sys, 'frozen', False):
application_path = os.path.dirname(os.path.realpath(sys.executable))
elif __file__:
application_path = os.path.dirname(__file__)
if application_path != "":
# Working directory change skipped due to the function to create TXT, CSV and HTML file on the local file
# system when thor is started from a read only network share
# os.chdir(application_path)
pass
if application_path == "":
application_path = os.path.dirname(os.path.realpath(__file__))
if "~" in application_path and not isLinux:
# print "Trying to translate"
# print application_path
application_path = win32api.GetLongPathName(application_path)
#if args.debug:
# log("DEBUG", "Application Path: %s" % application_path)
return application_path
except Exception, e:
log("ERROR","Error while evaluation of application path")
def log(mes_type, message):
if not args.debug and mes_type == "DEBUG":
return
# Prepare Message
orig_message = message
message = remove_non_ascii(message)
print "[%s]: %s" % (mes_type, message)
def remove_non_ascii(string, stripit=False):
nonascii = "error"
try:
try:
# Handle according to the type
if isinstance(string, unicode) and not stripit:
nonascii = string.encode('unicode-escape')
elif isinstance(string, str) and not stripit:
nonascii = string.decode('utf-8', 'replace').encode('unicode-escape')
else:
try:
nonascii = string.encode('raw_unicode_escape')
except Exception, e:
nonascii = str("%s" % string)
except Exception, e:
# traceback.print_exc()
# print "All methods failed - removing characters"
# Generate a new string without disturbing characters
nonascii = "".join(i for i in string if ord(i)<127 and ord(i)>31)
except Exception, e:
traceback.print_exc()
pass
return nonascii
def get_platform_full():
type_info = ""
try:
type_info = "%s PROC: %s ARCH: %s" % ( " ".join(platform.win32_ver()), platform.processor(), " ".join(platform.architecture()))
except Exception, e:
type_info = " ".join(platform.win32_ver())
return type_info
def pretty_print(no_empty=False, max_string=26):
x = PrettyTable(["File", "Size", "HHex", "HAscii", "Rule Matches"])
x.padding_width = 1
x.align["File"] = "l" # Left align rules
x.align["Size"] = "l" # Left align rules
x.align["HAscii"] = "l" # Left align rules
x.align["HHex"] = "l" # Left align rules
x.align["Rule Matches"] = "l" # Left align rules
for relPath in file_stats:
if no_empty and len(file_stats[relPath]["matches"]) < 1:
continue
# Add line
rules = "\n".join(rule[:max_string] for rule in file_stats[relPath]["matches"])
x.add_row([
remove_non_ascii(relPath[:max_string]),
file_stats[relPath]["size"],
file_stats[relPath]["firstBytes_Hex"],
file_stats[relPath]["firstBytes_Ascii"],
rules
])
print x # get_string(sortby="File")
x = PrettyTable(["Rule", "Match Count", "Files"])
x.padding_width = 1
x.align["Rule"] = "l" # Left align rules
x.align["Match Count"] = "l" # Left align rules
x.align["Files"] = "l" # Left align rules
for rule in rule_stats:
if no_empty and len(rule_stats[rule]["files"]) < 1:
continue
rule_name = rule[:max_string]
# Add line
files = "\n".join(remove_non_ascii(file[:max_string]) for file in rule_stats[rule]["files"])
x.add_row([
rule_name,
len(rule_stats[rule]["files"]),
files
])
print x
def save_stats(no_empty=False, identifier="yarAnalyzer", excel_patch=False):
with open("{0}_file_stats.csv".format(identifier), "w") as f_file:
f_file.write("File;Extension;Size;First Bytes in Hex;First Bytes in ASCII;MD5;SHA1;SHA256;Rule Match;Matched Strings\n")
for relPath in file_stats:
if no_empty and len(file_stats[relPath]["matches"]) < 1:
continue
# Extension
extension = os.path.splitext(relPath)[1].lower()
# Excel Patch
excel_addon = "=" if excel_patch else ""
# Write the line
try:
# Files with matches
if len(file_stats[relPath]["matches"]) > 0:
for rule in file_stats[relPath]["matches"]:
matched_strings = file_stats[relPath]["matches"][rule]
f_file.write("{0};{1};{2};{10}\"{3}\";{10}\"{4}\";{5};{6};{7};{8};{10}\"{9}\"\n".format(relPath,
extension,
file_stats[relPath]["size"],
file_stats[relPath]["firstBytes_Hex"],
file_stats[relPath]["firstBytes_Ascii"],
file_stats[relPath]["md5"],
file_stats[relPath]["sha1"],
file_stats[relPath]["sha256"],
rule,
matched_strings,
excel_addon
))
# Files with no matches
else:
f_file.write("{0};{1};{2};{10}\"{3}\";{10}\"{4}\";{5};{6};{7};{8};{10}\"{9}\"\n".format(relPath,
extension,
file_stats[relPath]["size"],
file_stats[relPath]["firstBytes_Hex"],
file_stats[relPath]["firstBytes_Ascii"],
file_stats[relPath]["md5"],
file_stats[relPath]["sha1"],
file_stats[relPath]["sha256"],
"-",
"-",
excel_addon
))
# Copy action
if args.t:
source_file = os.path.join(args.p, relPath)
target_file = os.path.join(args.t, os.path.basename(relPath))
print "[+] Copying sample with no match to {0}".format(target_file)
shutil.copyfile(source_file, target_file)
except Exception,e:
if args.debug:
traceback.print_exc()
print "Error while formatting line - skipping it - CSV results may be incomplete"
with open("{0}_rule_stats.csv".format(identifier), "w") as r_file:
r_file.write("Rule;Number of Matches;File;MD5;SHA1;SHA256\n")
for rule in rule_stats:
if no_empty and len(rule_stats[rule]["files"]) < 1:
continue
# Write the line
try:
# Rules with matches
if len(rule_stats[rule]["files"]) > 0:
for file in rule_stats[rule]["files"]:
r_file.write("{0};{1};{2};{3};{4};{5}\n".format(rule,
len(rule_stats[rule]["files"]),
file,
file_stats[file]["md5"],
file_stats[file]["sha1"],
file_stats[file]["sha256"]
))
# Rules without matches
else:
r_file.write("{0};{1};{2};{3};{4};{5}\n".format(rule,len(rule_stats[rule]["files"]),"-","-","-","-"))
except Exception,e:
print "Error while formatting line - skipping it - CSV results may be incomplete"
def print_welcome():
print "======================================================================="
print " ___ __ "
print " __ ______ ______/ | ____ ____ _/ /_ ______ ___ _____ "
print " / / / / __ `/ ___/ /| | / __ \/ __ `/ / / / /_ / / _ \/ ___/ "
print " / /_/ / /_/ / / / ___ |/ / / / /_/ / / /_/ / / /_/ __/ / "
print " \__, /\__,_/_/ /_/ |_/_/ /_/\__,_/_/\__, / /___/\___/_/ "
print " /____/ /____/ "
print " "
print " by Florian Roth"
print " December 2016"
print " Version %s" % __version__
print " "
print "======================================================================="
print " "
# MAIN ################################################################
if __name__ == '__main__':
# Parse Arguments
parser = argparse.ArgumentParser(description='yarAnalyzer - Yara Rules Statistics and Analysis')
parser.add_argument('-p', help='Path to scan', metavar='path', default='C:\\')
parser.add_argument('-s', help='Path to signature file(s)', metavar='sigpath', default="{0}".format(os.path.join(get_application_path(), './signatures')))
parser.add_argument('-e', help='signature extension', metavar='ext', default='yar')
parser.add_argument('-i', help='Set an identifier - will be used in filename identifier_rule_stats.csv and identifier_file_stats.csv', metavar='identifier', default='yarAnalyzer')
parser.add_argument('-m', help='Max file size in MB (default=10)', metavar='max-size', default=10)
parser.add_argument('-l', help='Max filename/rulename string length in command line output', metavar='max-string', default=30)
parser.add_argument('-f', help='Number of first bytes to show in output', metavar='first-bytes', default=6)
parser.add_argument('-o', help='Inventory output', metavar='output', default='yara-rule-inventory.csv')
parser.add_argument('-t', help='Target directory for samples without matches', metavar='output-samples', default='')
parser.add_argument('--excel', action='store_true', default=False, help='Add extras to suppress automatic conversion in Microsoft Excel')
parser.add_argument('--noempty', action='store_true', default=False, help='Don\'t show empty values')
parser.add_argument('--inventory', action='store_true', default=False, help='Create a YARA rule inventory only')
parser.add_argument('--printAll', action='store_true', help='Print all files that are scanned', default=False)
parser.add_argument('--debug', action='store_true', default=False, help='Debug output')
args = parser.parse_args()
# Error
if not args.inventory and not args.p:
print "[Error] At least one basic function must be used! Use either '-p' to scan a certain directory or " \
"'--inventory' to generate a rule inventory (of directory set with -s)."
parser.print_help()
# Print Welcome ---------------------------------------------------
print_welcome()
try:
t_hostname = os.environ['COMPUTERNAME']
except Exception, e:
t_hostname = os.uname()[1]
# Compile Yara Rules
yara_rules, yara_rule_infos = initialize_yara_rules(args.s, args.e)
# Inventory Only
if args.inventory:
generate_yara_inventory(args.o, yara_rule_infos)
sys.exit(0)
# Generate Stats Structure ----------------------------------------
# Global vars that will be filled and read during report generation
rule_stats = {}
file_stats = {}
generate_yara_stats_structure(yara_rules)
# Scan Path -------------------------------------------------------
scan_path(args.p, yara_rules, int(args.f))
# Result ----------------------------------------------------------
pretty_print(args.noempty, int(args.l))
save_stats(args.noempty, args.i, args.excel)