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truehunter.py
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truehunter.py
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#!/usr/bin/python
# This tool has been created as a PoC.
import argparse
import csv
import hashlib
import math
import os
import sys
import shutil
import sqlite3
import sys
import time
from binascii import hexlify
from collections import Counter
class TrueHunter:
def __init__(self, database, min_file_size, max_file_size, max_header_count, output_file):
self.db = DbUtils(database)
self.min_file_size = min_file_size
self.max_file_size = max_file_size
self.max_header_count = max_header_count
self.repeated_headers = self.db.get_all_headers()
self.first_check = []
self.fast_scan_positives = []
self.slow_scan_positives = []
self.ignored_files = [] # Bigger than maxFileSize
self.output_file = output_file
self.full_scan_completed = False
def fast_scan(self, location):
# Step one, check size and read first 8 bytes
for (path, subdir, files) in os.walk(location):
for filename in files:
file_path = os.path.join(path, filename)
try:
file_size = os.path.getsize(file_path) / 1024
if (file_size % 64 == 0) and (file_size > self.min_file_size):
# Read first 8 bytes, not a real header.
header = hexlify(open(file_path, "rb").read(8)).decode("utf-8")
if header in self.repeated_headers:
self.repeated_headers[header][0] += 1
else:
self.repeated_headers[header] = [1, filename]
self.first_check.append([file_path, file_size, header])
except:
print("[!] Error reading {}".format(file_path))
# Step two, check for header repetitions
for (file_path, file_size, header) in self.first_check:
if self.repeated_headers[header][0] <= self.max_header_count:
self.fast_scan_positives.append({"Path": file_path,
"File Size": file_size,
"Header": header})
def slow_scan(self):
# Memory efficient entropy calculation
for item in self.fast_scan_positives:
file_path = item.get("Path")
header = item.get("Header")
file_size = os.path.getsize(file_path)
entropy = 0.0
hash_func = hashlib.md5()
if (file_size / 1024) <= self.max_file_size:
hex_freq = {}
dec_freq = {}
with open(file_path, "rb") as f:
# Read chunks instead of mapping the whole file
while True:
data_chunk = f.read(65535)
if not data_chunk:
break
hash_func.update(data_chunk)
hex_freq = Counter(hex_freq) + (Counter(data_chunk))
# Transform (hex)byte values to (dec)byte and prepare counters for entropy calculation.
for byte in hex_freq:
dec_freq[byte] = float(hex_freq[byte]) / float(file_size)
# Entropy calculation.
for repetition in dec_freq.values():
if repetition > 0:
entropy -= repetition * math.log(repetition, 2)
if entropy > 7.998:
self.slow_scan_positives.append(
{"Path": file_path,
"Entropy": entropy, "MD5 Hash": hash_func.hexdigest(),
"File Size": file_size, "Header": header})
else:
self.ignored_files.append(
{"Path": file_path,
"Entropy": "Not calculated",
"File Size": file_size,
"Header": header})
self.full_scan_completed = True
def write_results(self):
# Write results to a CSV file
with open(self.output_file, 'w') as csvfile:
field_names = ["Path", "Entropy", "MD5 Hash", "File Size", "Header"]
writer = csv.DictWriter(csvfile, fieldnames=field_names, dialect=csv.excel)
writer.writeheader()
if self.full_scan_completed:
if len(self.slow_scan_positives) > 0:
writer.writerows(self.slow_scan_positives)
else:
print("[!] No files detected.")
if len(self.ignored_files) > 0:
writer.writerows(self.ignored_files)
print("[+] Manually check ignored files or repeat the scan increasing the maximum file size to " \
"scan (-M, --maxsize). ")
else:
if len(self.fast_scan_positives) > 0:
writer.writerows(self.fast_scan_positives)
else:
print("[!] No files detected.")
def add_repeated_headers(self):
# Update headers.db
headers = []
for item in self.repeated_headers:
# Only update if header repetition count is bigger than 10
if self.repeated_headers.get(item)[0] < 10:
continue
try:
extension = self.repeated_headers.get(item)[1][::-1].split('.')[0][::-1]
except:
extension = ""
header = item
headers.append([header, extension])
self.db.update_db(headers)
class DbUtils:
def __init__(self, database_file):
# Check if the db file exists.
if not os.path.isfile(database_file):
self.create_db(database_file)
else:
self.conn = sqlite3.connect(database_file)
self.c = self.conn.cursor()
def create_db(self, database_file):
# Create Database
self.conn = sqlite3.connect(database_file)
self.c = self.conn.cursor()
# Create table
self.c.execute('''CREATE TABLE headers
(header text, extension text, date text)''')
# Save (commit) the changes
self.conn.commit()
def update_db(self, headers_array):
date = time.strftime("%d/%m/%Y")
# headers array must contain arrays ['header','extension']
for header, extension in headers_array:
data = (header, extension, date,)
if self.get_header(header) is not None:
continue # avoid adding repeated headers
else:
self.c.execute('INSERT INTO headers VALUES (?,?,?)', data)
self.conn.commit()
def get_header(self, header):
self.c.execute('SELECT * FROM headers WHERE header=?', (header,))
return self.c.fetchone()
def get_all_headers(self):
self.c.execute('SELECT Header FROM headers')
x = self.c.fetchall()
headers = {}
if len(x) == 0:
return headers
for header in x:
headers[header[0]] = 0
return headers
def close_db(self):
self.conn.commit()
self.conn.close()
def update_db(th, database):
if sys.version_info.major > 2:
update = input("[?] Save repeated headers from this scan? [Y/N]")
else:
update = raw_input("[?] Save repeated headers from this scan? [Y/N]")
if update.lower() == "y":
try:
shutil.copyfile(database, "headers.db.bck")
print("[+] Database backup saved as headers.db.bck")
except IOError:
print("[!] Could not backup the existing database")
sys.exit(0)
th.add_repeated_headers()
print("[+] Database updated.")
sys.exit(0)
def main():
description = """ _ _ _
| | | | | |
| |_ _ __ _ _ ___| |__ _ _ _ __ | |_ ___ _ __
| __| '__| | | |/ _ \ '_ \| | | | '_ \| __/ _ \ '__|
| |_| | | |_| | __/ | | | |_| | | | | || __/ |
\__|_| \__,_|\___|_| |_|\__,_|_| |_|\__\___|_|
[+] Truehunter detects TrueCrypt containers and high entropy files (probably encrypted).\n[+] Autor: Andres Doreste\n[+] LinkedIn: https://www.linkedin.com/in/andres-doreste-239471136/\n[+] Notes: This project it's just a PoC\n"""
print(description)
parser = argparse.ArgumentParser(
description="Checks for file size, unknown header, and entropy of files to determine if they are encrypted containers.")
parser.add_argument("LOCATION", help="Drive or directory to scan.")
parser.add_argument("-D", "--database", dest="headers_file", default="headers.db",
help="Headers database file, default headers.db")
parser.add_argument("-m", "--minsize", dest="min_size", default=1024, type=int,
help="Minimum file size in Kb, default 1Mb.")
parser.add_argument("-M", "--maxsize", dest="max_size", default=102400, type=int,
help="Maximum file size in Kb, default 100Mb.")
parser.add_argument("-R", "--repeatHeader", dest="max_header", default=3, type=int,
help="Discard files with unknown headers repeated more than N times, default 3.")
parser.add_argument("-f", "--fast", dest="fast_scan", action="store_true", help="Do not calculate entropy.")
parser.add_argument("-o", "--outputfile", dest="output_file", default="scan_results.csv",
help="Scan results file name, default scan_results.csv")
args = parser.parse_args()
if not os.path.exists(args.LOCATION):
print("[!] Could not read {}".format(args.LOCATION))
sys.exit(0)
th = TrueHunter(args.headers_file, args.min_size, args.max_size, args.max_header, args.output_file)
start_time = time.time()
print("[>] Starting fast scan, it shouldn't take too long...")
th.fast_scan(args.LOCATION)
print("[+] {} files detected.".format(len(th.fast_scan_positives)))
print("[>] Done!")
if args.fast_scan:
print("[!] Scan finished in {0:.2f} seconds.".format(time.time() - start_time))
th.write_results()
update_db(th, args.headers_file)
print("[>] Starting entropy scan, staring at the screen won't help at this moment...")
th.slow_scan()
print("[+] {} files detected.".format(len(th.slow_scan_positives)))
print("[!] {} files possible encrypted files ignored".format(len(th.ignored_files)))
th.write_results()
print("[+] Results saved in {}".format(args.output_file))
print("[>] Scan finished")
update_db(th, args.headers_file)
if __name__ == "__main__":
main()