Diagnostic Page and Personalization Pages are opening without asking for passwor

Solution:

This is a intended behavior in R12 release, to control the access to the diagnostic page we need to change the profile value below.

Step1; Login to applications with sysadmin user.
Step2: Select system administrator responsibility from the list
Step3: Navigate to profile
Step4: Select for system option
Step5: Search for Utilities%
Step6: Change the profile Utilities: Diagnostic to "No"
Step7: Bounce middle tier services.
Step8: Retest the issue.