Personally i haven't seen any hacking/griefing on Arma yet but i am new enough to the series, On games like H1Z1 and 7 days to die hackers/griefers can make the game unplayable during certain updates where they absolutely run riot. A solution for personal server owners i have talked too is to ban any IP's from a number of asian/russian countries, one guy in-particular banned any names with Chinese type characters in their steam names, this may seem extreme and a tad racist but he said it cut the hacking down by 95%.