805 ILCS 105/105.30

Service of process on foreign corporation not authorized to conduct affairs in Illinois. If any foreign corporation conducts affairs in this State without having authority to conduct affairs, it shall be deemed that such corporation has designated and appointed the Secretary of State as an agent for process upon whom any notice, process or demand may be served. Service on the Secretary of State shall be made in the manner set forth in subsection (c) of Section 105.25 of this Act.