Windows Defeneder - Block all Office Apps from creating child processes

[sau001-petroineos]

OS (e.g. Windows 10 or macOS Sierra)

Versions of xlwings, Excel and Python (e.g. 0.11.8, Office 365, Python 3.7)

xlwings 0.30.12
Python 3.9.7

Describe your issue (incl. Traceback!)

1. We have an Excel addin that was developed on top of xlwings by an external contractor.
2. This Excel addin calls an internal REST API via Python code.
3. On some corporate deskops , we are seeing the following error message thrown by Windows Defender

Include a minimal code sample to reproduce the issue (and attach a sample workbook if required!)

Questions and concerns from our IT

• Excel cannot be allowed to spawn CMD.EXE - because this is too generic and will open the gates for any malicious macros to execute scripts.
• Why is xlwings spawning CMD.EXE ?

[fzumstein]

It runs Python via cmd.exe. You can try to see if "RunPython: Use UDF Server" checked makes a difference. Or you can migrate to xlwings Server that gets rid of local Python and any VBA, but is part of xlwings PRO.

[sau001-petroineos]

Hello @fzumstein ,
Thanks for the quick response, I tested with RunPython: Use UDF Server being checked. However ,it did not make any difference. The aforementioned Windows Defender alert popped up in both cases.

May I ask - What is the technical reason for choosing CMD.EXE to launch Python.exe as opposed to launching Python.exe directly?

Thanks,
Sau

[fzumstein]

I don't know of any other way than doing this via cmd.exe: https://github.com/xlwings/xlwings/blob/main/xlwings/addin/Main.bas#L270-L275

[sau001-petroineos]

Hello @fzumstein ,

Your code makes sense.

I am pondering whether it makes sense to try and launch the Python process directly , i.e. without using cmd.exe /c .

I would like to do a small proof of concept to find the answer to the above question .

Thinking aloud - I could copy over your Main.bas in my personal Addin project. and make changes to the Wscript.Run arguments.

What do you think?

[fzumstein]

Sure feel free! You're probably running into a problem with the LOG_FILE, which is used for error messages.

[sau001-petroineos]

Ok. This is what I have done.

• Created a new XLAM and added the file xlwings.bas as myxlwings
• Added a new VBA function HelloWorld in this XLAM
• Wired a new ribbon button to the VBA function HelloWorld
• The function HelloWorld invokes the RunPython from myxlwings.bas (renamed as NewRunPython)

Problem

tab = wb.sheets.active.name throws an error.

Question

Why can't Python find the Active Sheet ? See line 9 above