What is the ruling on one who seizes state property, such as usurping apartments still under the custodianship of companies, claiming that state ownership is permissible (halal)?

State property is public funds, legally protected just like private property. It is not permissible to transgress against it through theft, usurpation, or other means. Indeed, some scholars believe that its sanctity is even greater, because transgressing against it is a transgression against the rights of the entire society.