Source

oletools / oletools / rtfobj.py

#!/usr/bin/env python
"""
rtfobj.py - Philippe Lagadec 2013-04-02

rtfobj is a Python module to extract embedded objects from RTF files, such as
OLE ojects. It can be used as a Python library or a command-line tool.

Usage: rtfobj.py <file.rtf>

rtfobj project website: http://www.decalage.info/python/rtfobj

rtfobj is part of the python-oletools package:
http://www.decalage.info/python/oletools

rtfobj is copyright (c) 2012-2013, Philippe Lagadec (http://www.decalage.info)
All rights reserved.

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.

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 HOLDER 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.
"""

__version__ = '0.02'

#------------------------------------------------------------------------------
# CHANGELOG:
# 2012-11-09 v0.01 PL: - first version
# 2013-04-02 v0.02 PL: - fixed bug in main

#------------------------------------------------------------------------------
# TODO:
# - improve regex pattern for better performance?
# - allow semicolon within hex, as found in  this sample:
#   http://contagiodump.blogspot.nl/2011/10/sep-28-cve-2010-3333-manuscript-with.html

import re, sys, string, binascii

# REGEX pattern to extract embedded OLE objects in hexadecimal format:
# alphanum digit: [0-9A-Fa-f]
# hex char = two alphanum digits: [0-9A-Fa-f]{2}
# several hex chars, at least 4: (?:[0-9A-Fa-f]{2}){4,}
# at least 4 hex chars, followed by whitespace or CR/LF: (?:[0-9A-Fa-f]{2}){4,}\s*
PATTERN = r'(?:(?:[0-9A-Fa-f]{2})+\s*)*(?:[0-9A-Fa-f]{2}){4,}'
# improved pattern, allowing semicolons within hex:
#PATTERN = r'(?:(?:[0-9A-Fa-f]{2})+\s*)*(?:[0-9A-Fa-f]{2}){4,}'

# a dummy translation table for str.translate, which does not change anythying:
TRANSTABLE_NOCHANGE = string.maketrans('', '')


def rtf_iter_objects (filename, min_size=32):
    """
    Open a RTF file, extract each embedded object encoded in hexadecimal of
    size > min_size, yield the index of the object in the RTF file and its data
    in binary format.
    This is an iterator.
    """
    data = open(filename, 'rb').read()
    for m in re.finditer(PATTERN, data):
        found = m.group(0)
        # remove all whitespace and line feeds:
        #NOTE: with Python 2.6+, we could use None instead of TRANSTABLE_NOCHANGE
        found = found.translate(TRANSTABLE_NOCHANGE, ' \t\r\n\f\v')
        found = binascii.unhexlify(found)
        #print repr(found)
        if len(found)>min_size:
            yield m.start(), found

if __name__ == '__main__':
    if len(sys.argv)<2:
        sys.exit(__doc__)
    for index, data in rtf_iter_objects(sys.argv[1]):
        print 'found object size %d at index %08X' % (len(data), index)
        fname = 'object_%08X.bin' % index
        print 'saving to file %s' % fname
        open(fname, 'wb').write(data)