Yesterday I took my new phone to a mobile service shop... I wanted them to put a protection layer on my display. I have a pattern lock on my phone so I just put the display to sleep and gave it to him. He went to another room, and 15 minutes later he gave me the phone back.
My questions are: even though I have a pattern to unlock phone how can I make sure that he did not do anything suspicious to it? He was very strange. Could he have guessed or cracked the code? Is there a way to inject some kind of harmful code via usb cable? How can I check all the activity, not just browser history or
history.google.com but all the list of apps that were turned on? Or any other activity that might cause problems to me. Also, is there also anyway to inject some kind of harmfull code to a blocked phone using usb cable? And lets say that code would delete the pattern and gain the access to phone ?
I want to hear from a security expert. Should I do a factory reset would it delete everything that might be inserted by him to the phone ? just to make sure?
Or am I being paranoid? Thanks