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pe_patch.py
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#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# pe_patch.py
#
# Copyright 2017 Spencer McIntyre <[email protected]>
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
# * Neither the name of the nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
import argparse
import copy
import math
import sys
import pefile
__version__ = '1.0'
# .restore section contents:
# IMAGE_SECTION_HEADER (Name: .data\x00)
# IMAGE_SECTION_HEADER (Name: \x00)
# [ .data backup ]
IMAGE_SCN_CNT_INITLIALIZED_DATA = 1 << 6
IMAGE_SCN_MEM_DISCARDABLE = 1 << 25
IMAGE_SCN_MEM_READ = 1 << 30
IMAGE_SCN_MEM_WRITE = 1 << 31
SIZEOF_SECTION_HEADER = 40
def align_up(number, multiple):
return math.ceil(number / multiple) * multiple
def pe_insert(pe, data, offset):
pe.__data__ = pe.__data__[:offset] + data + pe.__data__[offset:]
return pe
def pe_patch(pe):
writable_sections = []
for section in pe.sections:
if section.Name == b'.restore':
raise RuntimeError('the .restore section is already present in the file')
if section.Characteristics & IMAGE_SCN_MEM_DISCARDABLE:
section.Characteristics ^= IMAGE_SCN_MEM_DISCARDABLE
if section.Characteristics & IMAGE_SCN_MEM_WRITE and section.SizeOfRawData:
writable_sections.append(section)
if not writable_sections:
raise RuntimeError('no writable sections were found')
first_raw_section = sorted([s for s in pe.sections if s.SizeOfRawData], key=lambda s: s.PointerToRawData)[0]
last_raw_section = next(reversed(sorted([s for s in pe.sections if s.SizeOfRawData], key=lambda s: s.PointerToRawData))) # as the data is ordered in the file
last_vir_section = next(reversed(sorted([s for s in pe.sections if s.SizeOfRawData], key=lambda s: s.VirtualAddress))) # as the data is ordered in memory
backup_section = pefile.SectionStructure(
pefile.PE.__IMAGE_SECTION_HEADER_format__,
file_offset=pe.sections[-1].get_file_offset() + SIZEOF_SECTION_HEADER,
pe=pe
)
backup_section.Name = b'.restore'
backup_section.Misc = 0
backup_section.VirtualAddress = align_up(last_vir_section.VirtualAddress + last_vir_section.SizeOfRawData, pe.OPTIONAL_HEADER.SectionAlignment)
backup_section.SizeOfRawData = 0
backup_section.PointerToRawData = last_raw_section.PointerToRawData + last_raw_section.SizeOfRawData
backup_section.PointerToRelocations = 0
backup_section.PointerToLinenumbers = 0
backup_section.NumberOfRelocations = 0
backup_section.NumberOfLinenumbers = 0
backup_section.Characteristics = (IMAGE_SCN_MEM_READ | IMAGE_SCN_CNT_INITLIALIZED_DATA)
if last_raw_section.__file_offset__ + (SIZEOF_SECTION_HEADER * 2) > first_raw_section.PointerToRawData:
offset = align_up(last_raw_section.__file_offset__ + (SIZEOF_SECTION_HEADER * 2), pe.OPTIONAL_HEADER.FileAlignment) - first_raw_section.PointerToRawData
pe.OPTIONAL_HEADER.SizeOfImage += SIZEOF_SECTION_HEADER
# need to insert data here to make room for the new section, then update
# each section
raise RuntimeError('insufficient space for the new section header')
pe.sections.append(backup_section)
pe.__structures__.append(backup_section)
pe.FILE_HEADER.NumberOfSections += 1
new_section = bytearray()
for section_idx, section in enumerate(writable_sections, -1): # start at -1 to account for the null-terminator section header
section = copy.copy(section)
section.Characteristics ^= IMAGE_SCN_MEM_WRITE
section.PointerToRawData = backup_section.PointerToRawData + ((len(writable_sections) - section_idx) * SIZEOF_SECTION_HEADER)
new_section += section.__pack__()
new_section += bytearray(SIZEOF_SECTION_HEADER) # add the null-terminator section header
for section in writable_sections:
new_section += section.get_data()
backup_section.Misc = len(new_section)
new_section += bytearray(int(align_up(len(new_section), pe.OPTIONAL_HEADER.FileAlignment) - len(new_section)))
pe_insert(pe, new_section, backup_section.PointerToRawData)
backup_section.SizeOfRawData = len(new_section)
pe.OPTIONAL_HEADER.SizeOfImage = align_up(pe.OPTIONAL_HEADER.SizeOfImage + len(new_section), pe.OPTIONAL_HEADER.SectionAlignment)
return pe
def main():
parser = argparse.ArgumentParser(description='ReflectiveUnloader PE Patcher', conflict_handler='resolve')
parser.add_argument('-v', '--version', action='version', version='%(prog)s Version: ' + __version__)
parser.add_argument('input_file', help='the pe file to patch')
parser.add_argument('output_file', help='the path to write the patched file to')
arguments = parser.parse_args()
pe_patch(pefile.PE(arguments.input_file)).write(arguments.output_file)
return 0
if __name__ == '__main__':
sys.exit(main())