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rip_raw.py
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rip_raw.py
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"""
Copyright 2022 Cado Security Ltd. All rights reserved
__________.__ __________
\______ \__|_____ \______ \_____ __ _ __
| _/ \____ \ | _/\__ \\ \/ \/ /
| | \ | |_> > | | \ / __ \\ /
|____|_ /__| __/ |____|_ /(____ /\/\_/
\/ |__| \/ \/
rip_raw.py
Takes a Raw Binary such as a Memoy Dump and Carves files and logs using:
- Text/binary boundaries
- File headers and file magic
- Log entry
Then puts them in a zip file for secondary processing
"""
import string
import os
import os.path
import argparse
import shutil
from datetime import datetime
import logging
from typing import Union
from typing import Optional
import mimetypes
try:
import re2 as re
except ImportError:
import re
import magic
# Used to extract strings
ASCII_BYTE = " !\"#\$%&'\(\)\*\+,-\./0123456789:;<=>\?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\[\]\^_`abcdefghijklmnopqrstuvwxyz\{\|\}\\\~\t"
n = 6
combined_reg = "(?:[%s]\x00|[%s]){%d,}" % (ASCII_BYTE, ASCII_BYTE, n)
combined_re = re.compile(combined_reg)
# Allow lines with 7+ chars
good_line = re.compile("[ 0-9a-zA-Z\.:]{7,}")
# Place extracted files here
EXTRACT_FOLDER = "/tmp/extracted_files/"
# Start extracted files with this
CARVED_MEMORY_PREPEND_FILENAME = "carved_memory_module_"
# 10 MB max filesize - Increasing this will slow performance
MAX_FILESIZE = 1024 * 10000
# Amount to read each iteration
READ_AMOUNT = 10240
# First files in the list match first
# Used for file carving
file_markers = [
# elf
"7f 45 4c 46 02 01 01",
# jpg
"ff d8 ff e0",
# 7z
"37 7a bc af 27",
# avi
"41 56 49 20",
# bz
"42 5A 68",
# docx
"50 4b 03 04 14",
# doc
"d0 cf 11 e0 a1",
# png
"89 50 4e 47",
# rar
"52 61 72 21",
# zip
"50 4b 30 30",
# exe
"4d 5a 90 00 03",
# 2021
"30 32 31 2d",
# 2022
"30 32 32 2d",
# ElfChnk EVT
"45 6c 66 43 68 6e 6b",
# Evtx chunk
"2a 2a 00 00",
# PNG
"89 50 4e 47 0d 0a 1a 0a",
# doc
"d0 cf 11 e0 a1 b1",
# pst
"21 42 4e a5 6f b5 a6",
# <html
"3c 68 74 6d",
# <HTML
"3c 48 54 4d",
# LNK File
"4c 00 00 00 01 14 02 00 00 00 00 00 c0 00 00 00 00 00 00 46",
# <plist
"70 6c 69 73 74",
]
def combined_strings_text(buf: bytes) -> str:
""" Get strings worth indexing """
results = []
buf = buf.replace(b"\xff", b"\x00")
decoded_text = buf.decode("utf8", "ignore")
lines = combined_re.findall(decoded_text)
current_regex = good_line
for line in lines:
if current_regex.search(line):
results.append(line)
text_output = "\n".join(results)
# Remove non printable
text_output = "".join(filter(lambda x: x in string.printable, text_output))
return text_output
def combined_strings(buf: bytes) -> int:
""" Returns how many strings are in the buffer """
return len(combined_strings_text(buf))
def write_file(file_count: int, data_bytes: bytes, text_mode: bool = False) -> None:
""" Write bytes to a file as text or binary """
file_extension = ".bin"
if text_mode:
file_extension = ".log"
mime_type = magic.from_buffer(data_bytes, mime=True)
if mime_type != "application/octet-stream":
extension = mimetypes.guess_extension(mime_type)
if extension:
file_extension = extension
file_name = CARVED_MEMORY_PREPEND_FILENAME + str(file_count) + file_extension
file_path = os.path.join(EXTRACT_FOLDER, file_name)
if text_mode:
text_content = combined_strings_text(data_bytes)
# Sub-split the text/log file if it contains dates
# Into a single file for each possible log entry
now = datetime.utcnow()
current_year = str(now.year)
last_year = str(now.year - 1)
if current_year in text_content or last_year in text_content:
log_parts = []
if current_year in text_content:
log_parts = text_content.split(current_year)
if last_year in text_content:
log_parts = text_content.split(last_year)
# Append delimeter year at the start of each split text
file_extension = ".log"
for split_count, part in enumerate(log_parts):
text_part = part
if split_count != 0:
text_part = current_year + part
file_name = (
CARVED_MEMORY_PREPEND_FILENAME
+ str(file_count)
+ "_"
+ str(split_count)
+ file_extension
)
file_path = os.path.join(EXTRACT_FOLDER, file_name)
with open(file_path, "w") as f:
f.write(text_part)
# Text but doesnt contain a date
else:
with open(file_path, "w") as f:
f.write(str(data_bytes))
else:
# Cant find a way to stop mypy erroring
with open(file_path, "wb") as f: # type: ignore
f.write(data_bytes) # type: ignore
def split_buffer(buffer: bytes, start_text: bool) -> int:
""" Split into text and data halves """
for file_marker in file_markers:
byte_marker = bytearray.fromhex(file_marker)
if byte_marker in buffer:
before = buffer.split(byte_marker)[0]
return len(before)
# No header matches - Split on text vs binary
count = 0
for b in buffer:
is_text = str(chr(b)).isprintable()
# If it started with text
if start_text:
if not is_text:
# We've found the split point
return count
# If starts with binary
else:
if is_text:
# We've found the split point
return count
count += 1
return count
def zip_folder(dir_name: str) -> str:
""" Zip a folder """
if not os.path.exists(dir_name):
os.mkdir(dir_name)
return shutil.make_archive(dir_name, "zip", dir_name)
def convert_memory_to_zip(filepath: str) -> Union[str, None]:
""" Convert memory to zip archive """
if os.path.exists(EXTRACT_FOLDER):
shutil.rmtree(EXTRACT_FOLDER)
os.makedirs(EXTRACT_FOLDER, exist_ok=True)
if os.path.isdir(filepath):
logging.warning(
f"{filepath} is a directory, skipping extraction. Likely already extracted successfully as Windows memory image"
)
return None
with open(filepath, "rb") as input:
file_count = 0
text_mode = False
data_buffer = bytes()
while True:
data = input.read(READ_AMOUNT)
if bytearray(READ_AMOUNT) == data:
# Skip empty sections
pass
else:
just_split = False
strings_length = combined_strings(data)
# TODO: Remove
split_point = 0
if text_mode:
# We're now looking at strings
if strings_length < 1000 or len(data_buffer) > MAX_FILESIZE:
# logging.info("Processed " + str(mb_processed) + " Megabytes")
# logging.info("Buffer length: " + str(len(data_buffer)))
split_point = split_buffer(data, True)
text_mode = False
file_count += 1
data_buffer += data[:split_point]
write_file(file_count, data_buffer, True)
data_buffer = data[split_point:]
just_split = True
else:
# Now we're looking at binary
if strings_length >= 1000 or len(data_buffer) > MAX_FILESIZE:
# logging.info("Processed " + str(mb_processed) + " Megabytes")
# logging.info("Buffer length: " + str(len(data_buffer)))
split_point = split_buffer(data, False)
text_mode = True
file_count += 1
write_file(file_count, data_buffer + data[:split_point], False)
data_buffer = data[split_point:]
just_split = True
if not just_split:
data_buffer += data
if len(data) < READ_AMOUNT:
logging.info("Less than expected data, exiting")
write_file(file_count, data_buffer + data[:split_point], text_mode)
break
zipped_evidence = zip_folder(EXTRACT_FOLDER)
logging.info(f"Returning zip_archive {zipped_evidence}")
return zipped_evidence
if __name__ == "__main__":
parser = argparse.ArgumentParser(
description="Takes a raw memory image and converts it to a zip archive of individual files"
)
parser.add_argument(
"-f", "--filename", help="The location of the memory image", required=True
)
logging.basicConfig()
logging.getLogger().setLevel(logging.INFO)
args = vars(parser.parse_args())
filename = args["filename"]
convert_memory_to_zip(filename)