Why does the 'Old School Ragnarok' server have you....

[MrMoogleX]

...download a .rar file with a Hack Tool that goes straight into your win32 file? That's a bit concerning.

[yC]

This have been explained many times in the forum.  You might want to include the filename of the detected file so we can see what is causing the problem.

A file being categorized as "hack tool" could be concerning and you are recommended take the necessary action whichever you wish to do.  Do not listen to anyone else if you find it risky you can delete the downloaded file and do a full scan of your computer.

Now, why is there such a file?  My guess is, as with many RO clients from countless RO servers, they include anti-cheat tools that monitor if you are running any third party programs to cheat or interfere with regular game-play.  For example, google "gepard shield rathena" for more information.

So in order to ensure you are playing the game without third party aid, the server's anti-cheat program might need to have access to the programs you are running, websites you are browsing and possibly any programs you are exchanging data with while the game is running.

Is that invasive?  It could be.  That's why the alert from Microsoft defender or certain anti-virus / anti-spyware.  It is up to you, to play or not to play.  You can always find another server that you feel safe playing instead.

[MCJV]

^Just like what the admin said but rest assured that Old School Ragnarok is one of the safest server to play since they are already open for 20 months and the players is still increasing.

[MrMoogleX]

It's not that I am scared in any way, shape, or form, but couldn't this possibly be a backdoor for disgruntled and upset GMS/users? Like, an easy way to access my personal PC remotely? And why don't other anti-cheats get flagged?

[yC]

but couldn't this possibly be a backdoor for disgruntled and upset GMS/users? Like, an easy way to access my personal PC remotely?

Definitely a possible case in any exe files you download from the internet.  That's why I started with "trust nobody other than yourself". 

And why don't other anti-cheats get flagged?

That is like asking why some illegal goods get detected at the border while others get smuggled into the country.  Could be depend on how hard it try to hide or how aggressive the anti-cheat is?  Also depend on the scanning program.

In addition to file scanning, the other line of defend you should have is some kind of traffic monitor or a firewall.  I think many anti-virus comes with that anyway (as you notice many anti-virus brands renamed themselves to "internet security").  They will monitor where programs are connecting to and blocks the connection if there is any malicious behavior detected.

[wLink]

Quite bit of servers seem to run a little of intrusive code that checks for your processes in the background, they mostly do to see if you aren't potentially running cheating software.

Also in the past, around when NovaRO thing started I think there was possibly a case of Gravity self-flagging their client to make it harder for private servers.