Prohibition is done by the officer when they look at your file. In my case, the prohibition was passed at the test day, but because my security checks were not in, after a few months after the test, the prohibition status changed to in progress again. Now both prohibition and security checks are in progress. My ATIP notes show that no single security update was made on my file since they submitted the request to csis more than 10 months ago.
The truth is, as it can be found on a number of MPs' websites, csis has a double standard in processing the screening from the nationals of some specific countries (please don't blame me on that I am biased, ircc/csis have also admitted this as well, you can do a web/youtube research for more information on this). It is a sad fact to know of this, but apparently there is no other way to expedite the process than being painfully patient (you can sign the petition on some of the MPs' websites if you like).