Is developing a computer program, whose source code was obtained illegally, considered a sin?

Assaulting the rights of software owners is not permissible شرعاً (religiously), and aiding in it is likewise impermissible. Your work in developing stolen software is considered aiding in this assault, therefore it is not permissible for you to do so. And if the company for which you are developing the software is a commercial insurance company, then the sin is doubled due to the combination of aiding in the assault and aiding in forbidden insurance.