If our work has been used without a signed contract or employment, this is unlawful use and we, as injured parties, can pursue our rights.
What else should you remember to protect yourself against company fraud and misappropriation of your work?
with your first phone list for sale and last name (it is best to prepare the file in a non-editable form, so the company will not be able to delete data from the work)
you have the right to include in your work a note informing that the work in question constitutes a work within the meaning of copyright law and is subject to protection provided for by law, and by transferring the work you do not transfer the rights to the work to your employer
if you send tasks via email, keep all copies of emails
if a given work is important to you and you want to be sure that it will not be misappropriated and used, you can ask a potential employer to sign an agreement that will outline the rules for using the given project
If you follow the above advice, it may be easier to pursue your rights in the future.
Summary
When undertaking a project for recruitment purposes, one should always exercise caution and ensure that the work is properly secured. Of course, ordering the preparation of an additional task should be aimed at assessing the skills of a given person. Unfortunately, one must also be prepared for unfair practices on the part of the employer, who illegally uses the work of an unemployed candidate, deriving benefits - including material ones.
If we have any doubts about the assigned task or the unlawful use of our work, it is worth discussing your concerns with a lawyer specializing in copyright.