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artifact_extractor.py
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artifact_extractor.py
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#!/usr/bin/python
# -*- coding: utf-8 -*-
"""Script to extract common Windows artifacts from source image and its shadow copies."""
from __future__ import print_function
import hashlib
import itertools
import logging
import os
import sys
import artifacts
import artifact_selector
import vsm
from datetime import datetime as dt
from dfvfs.helpers import volume_scanner
from dfvfs.resolver import resolver
WINDOWS_IDENTIFIER = 'nt'
if os.name == WINDOWS_IDENTIFIER:
from win32file import SetFileTime, CreateFileW, CloseHandle
from win32file import GENERIC_WRITE, FILE_SHARE_WRITE
from win32file import OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL
LOG_FILE = ''
IS_OLD = False
class ArtifactExtractor(volume_scanner.VolumeScanner):
"""Class that extracts common Windows artifacts."""
_READ_BUFFER_SIZE = 32768 # Class constant that defines the default read buffer size
_extracted = {}
@staticmethod
def _preserve_timestamps(file_entry, output_path):
"""Obtain and set (to preserve) original timestamps of exported files."""
stat_object = file_entry.GetStat()
if os.name == WINDOWS_IDENTIFIER:
accessed = created = modified = dt.now()
if stat_object.atime:
if stat_object.atime_nano:
accessed = dt.fromtimestamp((float(str(stat_object.atime) + '.' + str(stat_object.atime_nano))))
else:
accessed = dt.fromtimestamp(stat_object.atime)
if stat_object.crtime:
if stat_object.crtime_nano:
created = dt.fromtimestamp((float(str(stat_object.crtime) + '.' + str(stat_object.crtime_nano))))
else:
created = dt.fromtimestamp(stat_object.crtime)
if stat_object.mtime:
if stat_object.mtime_nano:
modified = dt.fromtimestamp((float(str(stat_object.mtime) + '.' + str(stat_object.mtime_nano))))
else:
modified = dt.fromtimestamp(stat_object.mtime)
handle = CreateFileW(output_path, GENERIC_WRITE, FILE_SHARE_WRITE, None, OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL, None)
SetFileTime(handle, created, accessed, modified) # does not seem to preserve nano precision of timestamps
CloseHandle(handle)
else:
os.utime(output_path, (stat_object.atime, stat_object.mtime))
def _check_unique(self, file_entry, md5):
"""Check if file of the same hash has been previously extracted."""
if file_entry.path_spec.location in self._extracted:
if md5 in self._extracted[file_entry.path_spec.location]:
return False
else:
self._extracted[file_entry.path_spec.location].append(md5)
return True
else:
self._extracted[file_entry.path_spec.location] = [md5]
return True
def export_file(self, partition_type, file_entry, output_path, recursive=False, string_to_match=None):
"""Export file to specified output path."""
md5_obj = hashlib.md5()
if len(output_path) > 254:
output_path = output_path[:251] + output_path[-4:]
if file_entry.IsDirectory():
for sub_file in file_entry.sub_file_entries:
if recursive and sub_file.IsDirectory():
self.export_file(partition_type, sub_file, os.path.join(output_path, sub_file.name), True,
string_to_match)
elif not sub_file.IsDirectory():
self.export_file(partition_type, sub_file, os.path.join(output_path, sub_file.name), False,
string_to_match)
elif file_entry.IsFile():
if string_to_match is not None and string_to_match.lower() not in file_entry.name.lower():
return
if not os.path.exists(os.path.dirname(output_path)):
os.makedirs(os.path.dirname(output_path))
stat_object = file_entry.GetStat()
if stat_object.size <= 0 and file_entry.path_spec.data_stream is None: # empty file
logging.info(u"Empty File:\t{}".format(file_entry.path_spec.location))
return
try:
in_file = file_entry.GetFileObject()
output = open(output_path, 'wb')
data = in_file.read(self._READ_BUFFER_SIZE)
while data:
md5_obj.update(data)
output.write(data)
data = in_file.read(self._READ_BUFFER_SIZE)
if output:
output.close()
if in_file:
in_file.close()
if (not self._check_unique(file_entry, md5_obj.hexdigest())) and \
(partition_type == 'VSHADOW' or IS_OLD):
os.remove(output_path)
logging.info(u"Duplicate:\t{}\t{}".format(file_entry.path_spec.location, md5_obj.hexdigest()))
else:
self._preserve_timestamps(file_entry, output_path)
logging.info(u"Extracted:\t{}\t{}".format(file_entry.path_spec.location, md5_obj.hexdigest()))
except IOError:
logging.error(u"IOError:\t{}".format(file_entry.path_spec.location))
pass
@staticmethod
def _get_file_entry(base_path_spec, artifact_location, data_stream=None):
"""Get file_entry object of specified path specification."""
if IS_OLD and 'Windows.old' not in artifact_location:
artifact_location = os.path.join('Windows.old' + artifact_location)
path_spec = base_path_spec
path_spec.location = artifact_location
path_spec.data_stream = data_stream
file_entry = resolver.Resolver.OpenFileEntry(path_spec)
if file_entry:
return file_entry
else:
logging.error(u"Missing:\t{}".format(artifact_location))
return None
@staticmethod
def _get_output_path(pp, partition_type, file_entry, artifact, output_base_dir, vsc_dir, username=''):
output_path = output_base_dir
filename = ''
if pp: # preserve path
elements = file_entry.path_spec.location.split('/')
if file_entry.IsFile():
filename = elements[-1]
elements = elements[:-1]
else:
elements = artifact[2].split('/')
if file_entry.IsFile():
filename = artifact[1].split('/')[-1]
if not pp and IS_OLD and file_entry.IsFile():
elements.insert(-1, 'Windows.old')
for element in elements:
output_path = os.path.join(output_path, element)
if not pp and artifact in artifacts.USER_DIR:
output_path = os.path.join(output_path, username)
if partition_type == 'VSHADOW':
output_path = os.path.join(output_path, vsc_dir)
if not pp and artifact in artifacts.USER_FILE:
output_path = os.path.join(output_path, 'Users', username)
if file_entry.IsFile():
output_path = os.path.join(output_path, filename)
if not pp and IS_OLD and file_entry.IsDirectory():
output_path = os.path.join(output_path, 'Windows.old')
return output_path
@staticmethod
def _get_vsc_ctime(base_path_spec):
return vsm.VSS_CREATION_TIMESTAMPS[base_path_spec.parent.store_index + 1]
def extract_artifacts(self, base_path_specs, output_base_dir, selection, pp): # pp = preserve path
# move non-vsc to front of list to be processed first
for base_path_spec in base_path_specs:
if base_path_spec.parent.type_indicator != 'VSHADOW':
base_path_specs.insert(0, base_path_specs.pop(base_path_specs.index(base_path_spec)))
for base_path_spec in base_path_specs:
try:
resolver.Resolver.OpenFileEntry(base_path_spec)
except RuntimeError:
logging.warning(u'Unable to open base path specification:\n{0:s}'.format(base_path_spec.comparable))
continue
# get partition type
partition = 'p1' # default value
partition_type = base_path_spec.parent.type_indicator
if IS_OLD and partition_type == 'VSHADOW':
continue # Windows.old directory does not contain VSCs
# get partition # of base path spec
try:
if partition_type == 'VSHADOW':
if hasattr(base_path_spec.parent.parent, 'location'):
partition = base_path_spec.parent.parent.location[1:]
else:
partition = base_path_spec.parent.location[1:]
logging.info('=' * 10 + " Extracting: " + base_path_spec.parent.location[1:] + ' ' + '=' * 10)
except AttributeError: # base_path_spec has no 'location' attribute
logging.info('=' * 10 + " Extracting: " + partition + ' ' + '=' * 10)
if pp: # preserve path
output_part_dir = os.path.join(output_base_dir, partition) # include partition in output dir structure
else:
output_part_dir = output_base_dir
vsc_dir = ''
if partition_type == 'VSHADOW':
print("Processing " + partition_type + ' (' + self._get_vsc_ctime(base_path_spec) + ')...')
vsc_dir = self._get_vsc_ctime(base_path_spec).replace(':', '').replace(' ', '@')
elif IS_OLD:
logging.info('=' * 10 + " Extracting: Windows.old " + '=' * 10)
print("Processing Windows.old...")
else:
print("Processing " + partition_type + '...')
for artifact in itertools.chain(artifacts.SYSTEM_FILE, artifacts.SYSTEM_DIR, artifacts.FILE_ADS):
if artifact[0] not in selection:
continue
# Get file entry
if artifact in artifacts.FILE_ADS:
file_entry = self._get_file_entry(base_path_spec, artifact[1], artifact[3])
else:
file_entry = self._get_file_entry(base_path_spec, artifact[1], None)
if file_entry is None:
continue
output_path = self._get_output_path(pp, partition_type, file_entry, artifact, output_part_dir, vsc_dir)
if file_entry.IsFile(): # artifacts.SYSTEM_FILE, artifacts.FILE_ADS
self.export_file(partition_type, file_entry, output_path)
elif file_entry.IsDirectory(): # artifacts.SYSTEM_DIR
self.export_file(partition_type, file_entry, output_path, artifact[3], artifact[4])
# artifacts.USER_FILE, artifacts.USER_DIR
if any(x in ['lnk_xp', 'iehist_xp', 'usrclass_xp'] for x in selection):
users_file_entry = self._get_file_entry(base_path_spec, '/Documents and Settings', None)
else:
users_file_entry = self._get_file_entry(base_path_spec, '/Users', None)
if users_file_entry is None:
continue
for user_file_entry in users_file_entry.sub_file_entries:
if not user_file_entry.IsDirectory():
continue
dir_name = user_file_entry.path_spec.location.split('/')[-1]
if dir_name in ['All Users', 'Default', 'Default User', 'Default.migrated', 'Public',
'LocalService', 'NetworkService']:
continue
for artifact in itertools.chain(artifacts.USER_FILE, artifacts.USER_DIR):
if artifact[0] not in selection:
continue
artifact_location = user_file_entry.path_spec.location + artifact[1]
file_entry = self._get_file_entry(base_path_spec, artifact_location, None)
if file_entry is None:
continue
output_path = self._get_output_path(pp, partition_type, file_entry, artifact, output_part_dir,
vsc_dir, dir_name)
if file_entry.IsFile():
self.export_file(partition_type, file_entry, output_path)
elif file_entry.IsDirectory():
self.export_file(partition_type, file_entry, output_path, artifact[3], artifact[4])
if IS_OLD: # stop processing VSCs
break
def main():
""" The main program function.
Returns:
A boolean containing True if successful or False if not.
"""
start_time = dt.now()
options = artifact_selector.get_selection()
if not options:
return False
date_timestamp = dt.now()
global LOG_FILE
LOG_FILE = os.path.join(options.dest, "_aExtractor.{}.txt".format(date_timestamp.strftime("%Y-%m-%d@%H%M%S")))
logging.basicConfig(filename=LOG_FILE, level=logging.INFO, format=u'[%(levelname)s] %(message)s')
if not os.name == WINDOWS_IDENTIFIER:
logging.warning('Script running on non-Windows host: Timestamps of extracted artefacts will not be preserved.')
for arg in dir(options):
if not arg.startswith('__') and not callable(getattr(options, arg)):
logging.info(u"{0}:\t{1}".format(arg, getattr(options, arg)))
mediator = vsm.VolumeScannerMediator()
artifact_extractor = ArtifactExtractor(mediator=mediator)
global IS_OLD
try:
base_path_specs = artifact_extractor.GetBasePathSpecs(options.source)
if not base_path_specs:
print('No supported file system found in source.\n')
logging.error('No supported file system found in source.')
return False
if os.path.exists(options.dest):
print('')
artifact_extractor.extract_artifacts(base_path_specs, options.dest, options.artifact, options.pp)
if options.old:
IS_OLD = True
artifact_extractor.extract_artifacts(base_path_specs, options.dest, options.artifact, options.pp)
IS_OLD = False
else:
print('Cannot find destination directory.\n')
logging.error('Cannot find destination directory')
return False
except KeyboardInterrupt:
print('\nAborted by user.')
return False
print('\nCompleted.')
print("\rTime Taken: {}".format(dt.now() - start_time))
logging.info("Time Taken: {}".format(dt.now() - start_time))
return True
if __name__ == '__main__':
if not main():
sys.exit(1)
else:
sys.exit(0)