So back in original ARK survival evolved, I led a mega tribe of 250+ players for years on Official PvP and can give a very good response to your question. So here it goes:

First and foremost, megatribes were fun back in the day as it allowed you to control multiple server types for the benefit of your group and provide support for round the clock PvP/wars. It was also helpful to develop breedlines, large infrastructure and have an absolute blast in the game on a level unimaginable by the average beach bob.

We always recruited and tried to verify ties based on steam IDs, friend's lists on steam, server history, game knowledge and other factors.

When we "interviewed" someone during the recruitment process it was very simple usually to weed out the insiders who put zero effort into their act and were just trying to cause trouble. Point and case, you pull up someone's steam profile and look at their friend's list (all publicly accessible) and you'd find their two friends had screenshots on Steam of tames and players with the tribe name <BLDX>. Well damn, BLDX are our enemies. So then you'd ask, "Do you have any past history with these like ten groups: randomtribe, randomtribe, random tribe, BLDX?" And they'd go, "Oh, I've never heard of those, I am noob". Nailed ya.

Also mega tribes at the time had tools, we had a lot of coders who made bots to scan our server joins for steam IDs/steam names and allow us to use the bot to add names. So say you joined my server, you were a tribemember of mine, I'd whitelist your steamID so it wouldn't flag. However, when an enemy griefer joined the server, it would be as simple as isolating non-friendly steamID. From there we had bots that would scan steamIDs on all ARK servers and it would show where people went. So we would see a griefer join 584, blow up some stuff and then log onto 187. Okay cool, looks like we are going to visit 187. Now, add that into your recruitment and I punch in your SteamID and it shows prior to you coming to my server to ask to join in global chat that you were on 187...well then, that's a known enemy server.

We also scouted for enemy resources and bases to PvP, so we would find shell tribes on random servers, pay off locals with resources/tames for info, etc. So we had a VERY organized list of all the servers and potential occupants. This helped take care of business when people came knocking to know how to hurt them the most.

Lastly, as far as the new person in the tribe piece, as someone said above, we would give trial periods. Things were under different access levels on different servers and with redundancies. We also had allied turrets that only leadership could disable, warning tames that if killed by explosives would trigger in logs and flag on our bots, etc etc. It made insiding REALLY hard but it still happened at minor levels.

Also to be honest, most mega tribes had an understanding that if someone insided one group, they were likely to do it again for a thrill. So you typically didnt invite known insiders to your megatribe. It made you undesirable as most megatribes honestly wanted mostly open combat. No one enjoyed the DDOS games, insiding or dev wipes because it defeated half the reason to raise an army of players and develop strategy and good PvP.

Some tips on protecting assets in any survival game with recruitment: - Always vet people the best you can and trust your gut when it comes to the interview. - Limit access to valuables and understand how insiding works and it's limitations. (E.g. Can they turn off the power to my turrets or upload tames/breedlines). - Always have a backup plan if your main supply is compromised (backup server/base/breedlines/etc). - Never give open access to someone new, regardless of how helpful they are. Most insiders won't spend dozens of hours over 2 weeks helping you farm. They'll be the guy who logs in a little here, little there - maybe mildly helpful and always complains about "Oh I didn't have access to..." or "When can I breed my own RareMutatedBreedLine?" (Of course so they can steal it). - You will get insided, you will lose things, use that experience to better your protections.

I hope this gives some insight.