Exception can't concatenate str to bytes python 3

[ANT1993]

Affected tool:
olevba

Describe the bug
With a specific document the olevba.analyze_macros() raise a exception in line 3413 and/or 3735 because vba_code is bytes.

oletools/oletools/olevba.py

Line 3413 in 0286347

self.vba_code_all_modules += vba_code + '\n'

oletools/oletools/olevba.py

Line 3735 in 0286347

vba_code_all_modules += vba_code + '\n'

File/Malware sample to reproduce the bug
https://www.virustotal.com/gui/file/1e6d72e0cbe34cf8e016857317b9f98050f492c3098971644ccef8b6c7db77c8/details
It's malware. If you want the file you can contact me.

(https://github.com/decalage2/oletools/files/4846132/1e6d72e0cbe34cf8e016857317b9f98050f492c3098971644ccef8b6c7db77c8.docx)

How To Reproduce the bug
Extract macros with olevba:
vbaparser = VBA_Parser(file_path) if vbaparser: if vbaparser.detect_vba_macros(): vbaparser.analyze_macros()

Version information:

• Ubuntu 16.04 64 bits
• Python 3.8 64 bits
• oletools version: 0.55.1

Additional context
I've solved the error decoding bytes to string if it's instance of bytes in line 3359.

oletools/oletools/olevba.py

Line 3359 in 0286347

# TODO vba_code = self.encode_string(vba_code)

Solved with:
if isinstance(vba_code, bytes): vba_code = bytes2str(vba_code)

[decalage2]

I finally found the bug and fixed it: see #455 (comment)

[decalage2]

This issue is now fixed in oletools 0.56.