Traffic Rules Change and 5MB Upload

Hi, my question refers to N360 version 21. I noticed that my internet uploads, which are typically less than 1MB, were nearly 5MB during a 30-minute period. Upon clicking Tasks>Check Security History, I discovered that Traffic Rules had been changed (without my intervention). Is it possible for Trojans to change Traffic Rules in Norton and steal files via undetectable uploads - I certainly could not find what file(s) had been uploaded through Check[ing] Security History. Any help in this regard will be greatly appreciated. Thanks!