1st January 2018 - WARNING - Some remote functions are slowly returning.
Rank setting and stat editing confirmed. Some of these may require the other player to give permission to do that first, but some may not, so be careful out there.
Original post from the 9th of April, 2017:
Q) Okay so is it definitely time to stay out of public GTA Online sessions if you're a PC player?
A) Quite possibly, as other people can now change your rank remotely, in addition to other things.
Explanation: Coders have recently discovered or perhaps more correctly been told, how to set another player's rank - something that will stick on your character unless you contact Rockstar Support and have that reversed, OR you delete that GTA Online character. This 'function' has already been included in a recent mod menu update that was created for the Online version of the PC game.
The major issue in my eyes is that as the innocent player minding their own business and playing the game properly, you've got no idea this sort of thing is about to happen to you, and very little recourse as just explained, and if that cheater using such mod menu sets your rank to 8000, well then you only need to use your imagination to realise what unfolds as a result (a lot more reports and cheater accusations are just two things).
That's not all either.
You can also be kicked from the session you're playing in, whether other players have reported you, voted to kick you or otherwise, again through the use of such mod menus, whereby the cheater only needs to browse to your name, select it, and a number of exploitative and griefing options are available.
When you're kicked, you will most likely be greeted with the message "Failed to find a compatible GTA Online session".
Finally, there's one other thing which is probably the most important - so I hope you got to this stage of the post. Your cash can also be taken - and because Rockstar Games has continually failed to add a third type of GTA Online monetary balance (Maze Bank/ Wallet Cash/ Shark Cards), it means those players who have spent real life money on the game, could see that disappearing.
This is not anything new - seasoned PC players will know about "insurance fraud" and it also hasn't been implemented in any mod menu - that I'm aware of - just yet, but it's definitely something to be on the watch for.
I hate to give these guys any more views, but I thought I'd leave a video below as a way of 'proving to the naysayers' that it is possible.
<This video has been removed from the YouTube channel it was posted on.>
Thanks for reading, take it easy out there!
EDITED 10/ APR/ 2017 - Thread title updated (thanks staff) to reflect on updated information that a 'new' type of fraud is possible, depleting whatever money you've earned at a fast rate, and that we may shortly see outfits being modified by these mod menu users.
If you do have any outfits you've worked hard for (limited/ special items) or don't want to see changed, please take pictures of your character outfits so that you have some form of recourse in the event that the problem cannot be rectified yourself.
EDITED 11/ APR/ 2017 -
- this video used to show insurance fraud taking place on another player.
EDITED 18 / APR / 2017 -
Some of these mod menus are starting to be shut down now, with similar notices to the below. Cheating in GTA Online on the PC version will be a far more rare occurrence now, however it will still be happening. For the most part though - legitimate players no longer need to fear public GTA Online sessions.
"After discussions with Take-Two Interactive, effective immediately we are ceasing all maintenance, development and distribution of the XXX
cheat menu services. We will be donating our proceeds to a charity designated by Take-Two. We apologize for any and all problems XXX
has caused to the Grand Theft Auto Online community."
(Where XXX is, it's one of the menu names).