Legal concern over “borrowed” code [closed]

Question

A company my friend works for (let's call him Me) recently unveiled a new face for their internal "networking" website. This new face looks remarkably like Facebook, and indeed, examination of the source code reveals that it's almost identical: The code, class names, and even the fonts are the same. There is also no indication that Facebook is in any way involved or aware.

I know this is unethical, but is it illegal? I can't find anything concrete about this to help Me decide what to do about it.

EDIT: We're talking front-end code. It does not appear to be linking to Facebook in any way.