If you google some obvious search phrases, you will find a number of web sites where students can pay people to take their online exams for them.

If a student has used such a service on one of my online exams, how can I prove it? The disciplinary board at my university has fairly strict standards when it comes to proof. When students have cooperated on exams, or copied from each other, there are often obvious similarities between their answers that you can point out to the board, but in a case like this there is nothing to compare to.

These have been open-book exams where any resources, except other people, are allowed, and there are no locked browsers or remote video proctoring.