Any code which will be able to change in the registry like yr home page, owner info,default search page etc, would be called Hacking a web browser or even any msg @ title, logo ect.

Trojans are power full to do like this and many more.

If a persone like me has access to yr sys, can do it mannualy using regedit.

This is the only way to be notice w.r.t a web browser(up to my knowledge)

I personaly had this problem.
If it is trojan then it can sed yr vital info to the hacker.