Disclosure of work history (without permit) in application

[Harju]

Has anyone had any practical (or anecdotal) experience in what repercussions a person faces when they disclose in the application a period where they worked without a permit. Simplied facts are that for about six months the person being sponsored worked illegally on visitor status until such time the employer received an LMO. The person then got a work permit which was subsequently changed to a study permit. The period of illegal work occurred 2 years ago and the person has been in-status and not offside with their activities since then. It is an outland sponsorship but residing Canada.