I have two computers and the goal is to move a functionality of a given file from computer A to computer B. The file is supposed to have a certain known functionality but it potentially could expose additional unwanted behavior. How to safely exchange the desired functionality of the file between the computers?
I believe that a question asked on such a general level might not have a single correct answer, therefore given the ambiguousness I would like to ask if there are perhaps some good practices and measures to be taken?
Aside from the general view, I would like to ask the same question in a very specific context.
I am thinking about doing some freelancing for small companies which most likely would mostly mean Excel VBA related programming. In such a case I would be developing spreadsheets on my computer and then I would need to transfer the files to a client. Whatever the measures I would take to keep my computers sterile I don't think it's a safe approach to assume that I can do that 100% of the time due to whatever reasons. Besides I can think of scenarios in which I am 100% sterile but a client's network is under a constant hacker's silent supervision and once the hacker discovers that there is a 3rd party sending files to the client, they may strike doing some damage and for at least initial time "framing" me into it.
So for example I have an Excel file with a procedure creating a "test.txt" file on a user's desktop. Is it possible to send the file (or functionality) safely to the client assuming that my computer is infected with an unknown malware?
The solution I thought of here is not sending a file, but instead a mail with a short instruction with a logic (of course more verbose) how to recreate the file:
- Create an empty Excel file
- Open Excel VBA IDE, add a module, paste the code
- Save as .xlsm
Sadly, it seems very crude and perhaps repelling to potential clients. Also it does not really protect me from the “framing” scenario.