Security against malicious users

Before all thank you for the borrowed help,  
 
good as it could protect the addresses that appear in the url, so that to the moment that some malicious user changes or place something in the address Url, don't pass anything, if not that it is in the same page, or something like that... 
 
The primordial thing is like I can make to protect the addresses url against that type of users that I thought that they didn't exist.