Port 135 is used by Windows for RPC (Remote Procedure Call) services, which facilitates communication between programs, whether they are on the same computer or across the network. This port is often targeted by malware, so it should be managed with care.
Port 139 is primarily used by NetBIOS session service. In Windows systems, it is utilized for file and printer sharing as well as other network communications. Like port 135, port 139 can also be a target for network-based attacks.
Port 445 is used for direct IP-based communication with SMB (Server Message Block) protocol, which is used for network file and print services. Due to its importance, port 445 is commonly open in corporate network environments but also needs to be properly secured to prevent malicious attacks.