This has happened on this server(31.3.245.170:2402) a few times now. Pretty sure it's happening on other servers but it's the first on our hive of 5 servers we've seen it on.
Hack involves knocking players unconscious then killing them and or killing them at the same time as sending them to an unconscious state.
So far we've not been able to detect the culprit via the logs because they're showing up as "KILLED by Error: No vehicle(uid=)"
This, in essence is undetected as far as what player is causing this. They do not appear in the logs as connecting/disconnecting without a Steam ID but do kill players without their name/Steam ID showing at all
Excerpt from the logs showing Date and times that this has happened yesterday are below. We've had it happen on the same server afaik once before a few days ago and it looks the same as these.
They can kill multiple players in this way and again, undetectable as far as which player is actually doing the dirty.