is Entity Framework secure?

Yes, this is secure. As its advance way of interacting with database it will be better to use this.
Here are some benefits of EF:
Provides dedicated functionality for CRUD operation (Create, Read, Update, Delete). Easy to implement CRUD operations.

>> If you want to replace the data store, it is very easy to replace without modifying the data access logic since all data access logic are present in higher level.

>> Easy to manage one to one, one to many and many to many relationship between tables.

>> Conceptual model can be represented in a better way.

>> Developer can reduce the code in classes and sub-classes for data access.

It is not a necessary to use entity framework, you can keep using the classic ado.net. Entity framework is not a replacement of ado.net, entity framework also uses the ado.net behind the scenes.

The main advantages are
1. It is easy to manage the code, especially when you are working on enterprise applications.

2. You will have to write less code for regular database operations. Instead entity framework will do most of this stuff and you can concentrate on your main application logic.

Note that you will not get any performance benefits by using entity framework. It also uses ado.net as its base layer. So calling stored procedures etc. using classic adp.net techniques will be faster as compared to having an extra entity framework layer inbetween.

check out this link

Entity Framework - Sample Application for Beginners[^]