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November 16, 2017 23:23
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extract pe sections and attempts to decompress them with lznt1
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# extract PE sections using pefile by name and decompress them using lznt1 via Rekall | |
# author: alexander hanel | |
# Rekall Memory Forensics | |
# Copyright 2014 Google Inc. All Rights Reserved. | |
# | |
# Author: Michael Cohen [email protected]. | |
# | |
# This program is free software; you can redistribute it and/or modify | |
# it under the terms of the GNU General Public License as published by | |
# the Free Software Foundation; either version 2 of the License, or (at | |
# your option) any later version. | |
# | |
# This program is distributed in the hope that it will be useful, but | |
# WITHOUT ANY WARRANTY; without even the implied warranty of | |
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
# General Public License for more details. | |
# | |
# You should have received a copy of the GNU General Public License | |
# along with this program; if not, write to the Free Software | |
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
# | |
"""Decompression support for the LZNT1 compression algorithm. | |
Reference: | |
http://msdn.microsoft.com/en-us/library/jj665697.aspx | |
(2.5 LZNT1 Algorithm Details) | |
https://github.com/libyal/reviveit/ | |
https://github.com/sleuthkit/sleuthkit/blob/develop/tsk/fs/ntfs.c | |
""" | |
import array | |
import cStringIO | |
import logging | |
import struct | |
import pefile | |
import sys | |
def get_displacement(offset): | |
"""Calculate the displacement.""" | |
result = 0 | |
while offset >= 0x10: | |
offset >>= 1 | |
result += 1 | |
return result | |
DISPLACEMENT_TABLE = array.array( | |
'B', [get_displacement(x) for x in xrange(8192)]) | |
COMPRESSED_MASK = 1 << 15 | |
SIGNATURE_MASK = 3 << 12 | |
SIZE_MASK = (1 << 12) - 1 | |
TAG_MASKS = [(1 << i) for i in range(0, 8)] | |
def decompress_data(cdata, logger=None): | |
"""Decompresses the data.""" | |
if not logger: | |
lznt1_logger = logging.getLogger("ntfs.lznt1") | |
else: | |
lznt1_logger = logger.getChild("lznt1") | |
# Change to DEBUG to turn on module level debugging. | |
lznt1_logger.setLevel(logging.ERROR) | |
in_fd = cStringIO.StringIO(cdata) | |
output_fd = cStringIO.StringIO() | |
block_end = 0 | |
while in_fd.tell() < len(cdata): | |
block_offset = in_fd.tell() | |
uncompressed_chunk_offset = output_fd.tell() | |
block_header = struct.unpack("<H", in_fd.read(2))[0] | |
lznt1_logger.debug("Header %#x @ %#x", block_header, block_offset) | |
if block_header & SIGNATURE_MASK != SIGNATURE_MASK: | |
break | |
size = (block_header & SIZE_MASK) | |
lznt1_logger.debug("Block size %s", size + 3) | |
block_end = block_offset + size + 3 | |
if block_header & COMPRESSED_MASK: | |
while in_fd.tell() < block_end: | |
header = ord(in_fd.read(1)) | |
lznt1_logger.debug("Tag %#x", header) | |
for mask in TAG_MASKS: | |
if in_fd.tell() >= block_end: | |
break | |
if header & mask: | |
pointer = struct.unpack("<H", in_fd.read(2))[0] | |
displacement = DISPLACEMENT_TABLE[ | |
output_fd.tell() - uncompressed_chunk_offset - 1] | |
symbol_offset = (pointer >> (12 - displacement)) + 1 | |
symbol_length = (pointer & (0xFFF >> displacement)) + 3 | |
output_fd.seek(-symbol_offset, 2) | |
data = output_fd.read(symbol_length) | |
# Pad the data to make it fit. | |
if 0 < len(data) < symbol_length: | |
data = data * (symbol_length / len(data) + 1) | |
data = data[:symbol_length] | |
output_fd.seek(0, 2) | |
lznt1_logger.debug( | |
"Wrote %s @ %s/%s: Phrase %s %s %x", | |
len(data), in_fd.tell(), | |
output_fd.tell(), symbol_length, symbol_offset, | |
pointer) | |
output_fd.write(data) | |
else: | |
data = in_fd.read(1) | |
lznt1_logger.debug("Symbol %#x", ord(data)) | |
output_fd.write(data) | |
else: | |
# Block is not compressed | |
data = in_fd.read(size + 1) | |
output_fd.write(data) | |
result = output_fd.getvalue() | |
return result | |
def run(): | |
if len(sys.argv) < 2: | |
print "usage: script.py file.bin" | |
return | |
try: | |
pe = pefile.PE(sys.argv[1]) | |
for count, section in enumerate(pe.sections): | |
data = pe.sections[count].get_data() | |
dec_data = decompress_data(data) | |
if dec_data: | |
print "Section %s decompressed successfully" % section.Name | |
with open(str(sys.argv[1]) + "." + str(count) + ".bin", "wb") as out: | |
out.write(dec_data) | |
except Exception as e: | |
print e | |
return | |
run() |
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