Is it permissible to receive unemployment benefits while having undeclared income, the declaration of which would lead to the termination of the benefits?

If the work is forbidden or prohibited because it harms the interests of the country, then it is not permissible to practice it. However, if it is permissible and does not harm the country, then there is no objection to practicing it. If the amount obtained from it is sufficient for one's needs, then it is not permissible to take the salary allocated for the unemployed. If the income is not sufficient, it is permissible to take it to meet one's needs.