Any application can be a possible target of denial-of-service (DoS) attacks. From the application side, the developers should minimize how many operations are performed for non-authenticated users. This will keep the application running as quickly as possible and using the least amount of system resources to help minimize the impact of any such attacks.

It is imperative that applications do checks when each function or portion of the application is accessed to ensure that the user is properly authorized. Without continual checks each time a function is accessed, an attacker could forge requests to access portions of the application where authorization has not been granted. An injection attack is where a malicious actor sends commands or other arbitrary data through input and data fields with the intent of having the application or system execute the code as part of its normal processing and queries. Cross-site scripting occurs when an attacker is able to send untrusted data to a user's browser without going through validation processes. Cross-site request forgery occurs when an attack forces an authenticated user to send forged requests to an application running under their own access and credentials.

Explanation
Policy drives all programs and functions in the organization; the organization should not conduct any operations that don't have a policy governing them. Penalties may or may not be an element of policy, and severity depends on the topic. Multifactor authentication and homomorphic encryption are red herrings here.