99 Camry LE Leaks

I have had this problem since I first bought my vehicle in 03. I had the dealer check it out, they claimed it was from a hole the previous owner drilled into the firewall and did not plug properly. I looked for this hole when I got the car back and didnt see anything, I gave up giving them the benefit of a doubt. The problem has not gone away. I find water on both my driver's and passenger's side floorboards almost everytime it rains. I trace the water up to around 8" up from the floorboard on coming out of the upper side of the side panels by the pedals. I have a sunroof, which I suspect might be the culprit. Are there any easy fixes or ways of diagnosing the problem that I could do at home? Thanks for the help!