If your students are behaving like that then run of the mill cheating is the least of your problems. And I can't see how a thesis can be properly defended except in real time, we aren't talking about marking an exam here but getting the student to make it clear that he or she really does understand the work presented (in my case over a hundred pages of experimental design, execution, results, and interpretation) and can explain it and defend it against criticism.

Some universities still require PhD theses to be defended in public, for instance Oslo: ==== begin quote

The PhD degree is conferred on the basis of:

completion of the programme's educational component

the doctoral thesis

the doctoral examination

The doctoral examination consists of the trial lecture and the public defence of the thesis, also known as the disputation.

=== end quote