Questions at the interview?

At the job interview I was asked a question:

You are provided with standalone software which is an [(executable file).exe], which runs itself without any other files or libraries. At the same time you are documented with specifying inputs and outputs for each input. Write solutions and algorithms (pseudo code is OK) to identify ALL bugs of that software.

I tried to find documents to try to understand but still could not find it, hope everyone suggests. Thanks!