Interesting problem. There's some good ideas in here, and I think you might get some better ones if you add more details. You said that you have been assigned

Interesting problem. There's some good ideas in here, and I think you might get some better ones if you add more details. You said that you have been assigned the task of replacing the "zombie" program, which I assume means that you are to write a new one that interfaces whatever depends on the zombie. If the zombie were to die right now, how severe would the consequences be? On the scale of total disruption of business to minor inconvenience that could be worked around until it's fixed? How complex is the zombie? What is the nature of the state that was supplied by the lost configuration file? Is it stuff like which port to listen on and how to connect to its database, or is it more like huge tables of magic values that won't be easy to figure out again? Do you currently have enough information about the zombie to write a replacement? Do you have what you need to test your replacement before deploying it? If you are confident you have sufficient information to write the replacement, how long do you think you need to write and test that? You said the zombie runs on a physical server. What operating system? What language/runtime/stack is the zombie based on?