Add parser for .doc files (Word 2003 and earlier)

Works with Python 2.7, still have to check with other versions

Add parser for .doc files (Word 2003 and earlier)
Works with Python 2.7, still have to check with other versions
Christian Herdtweck
1 parent c49a5078
Showing 1 changed file with 157 additions and 4 deletions
oletools/msodde.py
@@ -6,7 +6,7 @@ msodde is a script to parse MS Office documents
 (e.g. Word, Excel), to detect and extract DDE links.
  
 Supported formats:
-- Word 2007+ (.docx, .dotx, .docm, .dotm)
+- Word 97-2003 (.doc, .dot), Word 2007+ (.docx, .dotx, .docm, .dotm)
  
 Author: Philippe Lagadec - http://www.decalage.info
 License: BSD, see source code or documentation
@@ -47,8 +47,9 @@ from __future__ import print_function
 # 2017-10-18 v0.52 PL: - first version
 # 2017-10-20       PL: - fixed issue #202 (handling empty xml tags)
 # 2017-10-25       CH: - add json output
+# 2017-10-25       CH: - parse doc
  
-__version__ = '0.52dev2'
+__version__ = '0.52dev3'
  
 #------------------------------------------------------------------------------
 # TODO: detect beginning/end of fields, to separate each field
@@ -114,9 +115,154 @@ def process_args():
  
     return args
  
+# from [MS-DOC], section 2.8.25 (PlcFld):
+# A field consists of two parts: field instructions and, optionally, a result. All fields MUST begin with
+# Unicode character 0x0013 with sprmCFSpec applied with a value of 1. This is the field begin
+# character. All fields MUST end with a Unicode character 0x0015 with sprmCFSpec applied with a value
+# of 1. This is the field end character. If the field has a result, then there MUST be a Unicode character
+# 0x0014 with sprmCFSpec applied with a value of 1 somewhere between the field begin character and
+# the field end character. This is the field separator. The field result is the content between the field
+# separator and the field end character. The field instructions are the content between the field begin
+# character and the field separator, if one is present, or between the field begin character and the field
+# end character if no separator is present. The field begin character, field end character, and field
+# separator are collectively referred to as field characters.
  
  
-def process_file(filepath):
+def process_ole_field(data):
+    """ check if field instructions start with DDE
+
+    expects unicode input, returns unicode output (empty if not dde) """
+    #print('processing field \'{0}\''.format(data))
+
+    if data.lstrip().lower().startswith(u'dde'):
+        #print('--> is DDE!')
+        return data
+    else:
+        return u''
+
+
+OLE_FIELD_START = 0x13
+OLE_FIELD_SEP = 0x14
+OLE_FIELD_END = 0x15
+OLE_FIELD_MAX_SIZE = 1000   # max field size to analyze, rest is ignored
+
+
+def process_ole_stream(stream):
+    """ find dde links in single ole stream
+
+    since ole file stream are subclasses of io.BytesIO, they are buffered, so
+    reading char-wise is not that bad performanc-wise """
+
+    have_start = False
+    have_sep = False
+    field_contents = None
+    result_parts = []
+    max_size_exceeded = False
+    idx = -1
+    while True:
+        idx += 1
+        char = stream.read(1)    # loop over every single byte
+        if len(char) == 0:
+            break
+        else:
+            char = ord(char)
+
+        if char == OLE_FIELD_START:
+            #print('DEBUG: have start at {}'.format(idx))
+            #if have_start:
+            #    print("DEBUG: dismissing previous contents of length {}"
+            #          .format(len(field_contents)))
+            have_start = True
+            have_sep = False
+            max_size_exceeded = False
+            field_contents = u''
+            continue
+        elif not have_start:
+            continue
+
+        # now we are after start char but not at end yet
+        if char == OLE_FIELD_SEP:
+            #print('DEBUG: have sep at {}'.format(idx))
+            have_sep = True
+        elif char == OLE_FIELD_END:
+            #print('DEBUG: have end at {}'.format(idx))
+
+            # have complete field now, process it
+            result_parts.append(process_ole_field(field_contents))
+
+            # re-set variables for next field
+            have_start = False
+            have_sep = False
+            field_contents = None
+        elif not have_sep:
+            # check that array does not get too long by accident
+            if max_size_exceeded:
+                pass
+            elif len(field_contents) > OLE_FIELD_MAX_SIZE:
+                #print('DEBUG: exceeded max size')
+                max_size_exceeded = True
+
+            # appending a raw byte to a unicode string here. Not clean but
+            # all we do later is check for the ascii-sequence 'DDE' later...
+            elif char < 128:
+                field_contents += unichr(char)
+                #print('DEBUG: at idx {:4d}: add byte {} ({})'
+                #      .format(idx, unichr(char), char))
+            else:
+                field_contents += u'?'
+                #print('DEBUG: at idx {:4d}: add byte ? ({})'
+                #      .format(idx, char))
+    #print('\nstream len = {}'.format(idx))
+
+    # copy behaviour of process_xml: Just concatenate unicode strings
+    return u''.join(result_parts)
+
+
+def process_ole_storage(ole):
+    """ process a "directory" inside an ole stream """
+    results = []
+    for st in ole.listdir(streams=True, storages=True):
+        st_type = ole.get_type(st)
+        if st_type == olefile.STGTY_STREAM:      # a stream
+            stream = None
+            links = ''
+            try:
+                stream = ole.openstream(st)
+                #print('Checking stream {0}'.format(st))
+                links = process_ole_stream(stream)
+            except:
+                raise
+            finally:
+                if stream:
+                    stream.close()
+            if links:
+                results.append(links)
+        elif st_type == olefile.STGTY_STORAGE:   # a storage
+            #print('Checking storage {0}'.format(st))
+            links = process_ole_storage(st)
+            if links:
+                results.extend(links)
+        else:
+            #print('Warning: unexpected type {0} for entry {1}. Ignore it'
+            #      .format(st_type, st))
+            continue
+    return results
+
+
+def process_ole(filepath):
+    """ find dde links in ole file
+
+    like process_xml, returns a concatenated unicode string of dde links or
+    empty if none were found. dde-links will still being with the dde[auto] key
+    word (possibly after some whitespace)
+    """
+    #print('Looks like ole')
+    ole = olefile.OleFileIO(filepath, path_encoding=None)
+    text_parts = process_ole_storage(ole)
+    return u'\n'.join(text_parts)
+
+
+def process_xml(filepath):
     z = zipfile.ZipFile(filepath)
     data = z.read('word/document.xml')
     z.close()
@@ -134,11 +280,18 @@ def process_file(filepath):
         # concatenate the attribute of the field, if present:
         if elem.attrib is not None:
             text += elem.attrib[TAG_W_INSTRATTR]
-    
  
     return text
  
  
+def process_file(filepath):
+    """ decides to either call process_xml or process_ole """
+    if olefile.isOleFile(filepath):
+        return process_ole(filepath)
+    else:
+        return process_xml(filepath)
+
+
 #=== MAIN =================================================================
  
 def main():