You are asked to block malicious applications regardless of the port number being used.

AppFW and APPID are two application security features that can be used to block malicious applications regardless of the port number being used. AppFW provides policy-based enforcement and control on traffic based on application signatures. By using AppFW, you can block any application traffic not sanctioned by the enterprise. APPID identifies applications based on their behavior and characteristics, regardless of port, protocol, or encryption method. By using APPID, you can classify applications and apply appropriate security policies to them123 References:

AppSecure: Application Visibility and Control Solution Brief

Application Firewall | Junos OS | Juniper Networks

Security Policy Applications and Application Sets | Junos OS | Juniper Networks