How can I debug a binary that has no debugging symbols?

Question

I have an executable that remained from a previous programmer ( and no source code is available ). The thing is, it started to work kind of buggy and I'm trying to figure out why. The tool reads data from somewhere and populates a combobox with it. Is there anyway I could debug it, and see where is it getting the data from?

What tool can do this? Do you have some examples on doing this?

Answer 1

There's a whole palette of tools in the SysInternals suite, formerly by Mark Russinovich, now on Microsoft's Web site (still free, I think). There's something called FileMonProcessMonitor, for example, which tracks opening and closing files, and probably also reading (and more).

There are also similar tools for monitoring network/Internet access.

These tools let you look at many aspects of the program from a "black box" perspective, i.e. without going into source or machine code - just seeing what it does.