I've been well versed on this topic in past and checked many mods etc over at the original unreal and tried to do something against it, only to be later shunned anyway. Indeed many things are possible, including overwriting native files, corrupting configs, setting keybinds to join certain server and do automatic attacks or spam on keys like each time you hit a forward movement key it spams the server with "Fuck You" over and over. Seen those things happen so many times. Sadly, with too tightened security its easy to scapegoat some people and blame it on them and ban them from servers evenif they were just victims and didn't actually do it.
Unfortunately with global overruling security mods the later is the case, people get banned and victimized for something they took no part in.
Therefore, we made our own fixes/measures and didn't use the mass security mods/stuff or patches and it worked just well. Sadly some people have no clue and will have no clue it appears.