Is there really no way to make anti-cheat on Linux that can't be bypassed? I don't know much about this, but it seems very difficult to make an anti-cheat for a platform where you can make changes in the kernel.
There's also practical limits to how much data you can filter out in complex 3D games, both due to performance constraints, and because culling information too perfectly can cause things to pop into existence too late under real-world network latency. The effectiveness of ESP cheats can be reduced, but not eliminated in practice.
This player is posting 30 auctions per second. Bot.
This player is turning at a rate of 500 radians per second to make perfect headshots. Bot.
to be honest, it isn’t particularly good - all serious CS2 games operate on a third party provider with a kernel-level anti-cheat. also, the cs2 update banned people for spinning their mouse too fast [2].
[0]: https://www.reddit.com/r/GlobalOffensive/comments/5u2xly/eli...
Even with turnrate, reaction time is very relevant. Reaction time allows you to silence enemies midcast, or to pop a shield, or a BKB, or some other instant measure. Turnrate doesn't mean reaction time doesn't matter, it means the direction you are facing matters.
As for precision, yes it does matter, ask any Phoenix player who gets hexed mid-flight.
People cheat in Dota in these very terms, it's absurd to argue it doesn't matter.
This problem is magnified in a shooter game, which would be unplayable with that kind of batching, but where a cheater with an aimbot is actually impossible for a legitimate player to beat.
If your game allows your sights to just teleport on people's heads and take that as the winning condition then that just sounds like bad design, there's no reason to allow infinitely fast movement and omitting strategy even from a shooter
This is interesting, because I feel like the fundamental gameplay of an fps is players exposing themselves to each other's field of view, and then trying to click the other's head first. Skill is a measure of map knowledge (so you can try to expose yourself to a possible field of view but not where the enemy is actually looking at that moment) and speed of clicking head.
How would you design FPSs to remove this "bad game design?"
I think we just need to accept that bots will always be better at reaction based KPIs & abusing "knowing" too much game state, we should just remove those conditions.
1) Move most of the application logic to the server, the client should be a fairly dumb terminal that knows how to render and accept inputs, and only receives the state that it needs. No more spying issues.
2) Just give everybody auto aim & immediate/auto controlled firing, etc. No more aim bot issues.
3) Improve the quality of gameplay around the types of interactions which bots are bad at. Decision making, strategy, communication, execution, adaptation.
But some people just want to play competitive fps shooters. And currently obnoxious anticheat toolkits are the way to provide that, unfortunately.
This isn't possible. And this explains why: https://www.youtube.com/watch?v=WFw4F2AyaP4
We can only minimize the amount of extra information given to the client, not eliminate it. And at high enough skill levels, even 1-2ms of extra information will always be actionable, even by humans (not just bots).
From the servers perspective you always kinda do that for fast movements as the client send rate usually isn't more than 60hz.
That's just discount wallhacks. Fortnite has it and you're basically forced to use it even if you have no hearing issues, because it provides a massive advantage.
Doing everything server side does prevent cheating.
No. Server side only protects against some types of cheats, such as telling the server that your bullet in an FPS is actually a grenade.
It cannot prevent snapping your aim to a target on screen.
The other half is much harder to solve. For a simple example - my client knows that there is an enemy player around a corner. It knows exactly where that player is, because that player is walking, and making noise. A cheats could allow the cheater to see his opponent's player's model through the wall.
For a more blatant example, consider cheats in a first-person shooter that just snap your aim to the nearest enemy's head. This involves zero violation of the game's logic, and also makes the game completely unplayable for everyone in a lobby.
You can replace a playermodel with wider "sound coming from around here" if you want to make it even harder for a cheat to pinpoint a sound
This requires the server to calculate line of sight checks for every player, which is costly, requires loading the entire geometry into the server and would be horribly prone to latency. Then you're looking at potential performance problems on the client due to only knowing about a player the second its in view and having to stream the assets to the GPU, which if don't happen in time for the frame you'll experience as hitching.
> You already know where an enemy is if you hear them behind the wall
Yes but this requires using your brain rather than just seeing them straight up through a wall.
One non-trivial part seems to me that if you walk around a corner you don't want to wait 50ms (your ping) for the server to send enemy locations you can now see. Ideally every tick the server would be sending all enemies that you could potentially see before the next tick depending on what your movement packets that it hasn't yet received turn out to be. Wouldn't entirely eliminate advantage from cheating (e.g: a cheater walking around a corner could still see enemies up to a tick/~15ms in advance) but would hopefully make this form of cheating significantly less worthwhile.
This is unworkable for fast paced games.
You know they are somewhere behind the wall, you don't know which exact angle they are behind the wall, because headphones and our ears don't work with that degree of accuracy.
The cheater can just swing the corner with his cursor already pre-positioned exactly on his target. Between peeker's advantage (inherent to any online game with latency) and human reaction time, there's not a lot you can do to fight that.
There could simply be a developer option that disables these integrity checks but subsequently breaks online games that rely on them. Valve could also offer a module that allows signed user-space binaries access to kernel space, which would be an improvement over Windows offers in that anti-cheat wouldn't need to live in the kernel.
I think that's a fine trade off.
Secure Boot in theory isn't even necessary, only TPM2. Secure boot only ensure that you are actually booting into a binary that you expect to boot in this case, so if your binary is actually different it would result in different PCR values in the TPM indicating something is wrong.
Sadly a lot of end user software (flatpak, ...) isn't packaged & signed in a way which would allow for full "only run software I allow by importing public keys" (read Linux IPE[2]), but what can you do, only your best I suppose...
[1]: https://www.freedesktop.org/software/systemd/man/systemd-sys...
Those things are all possible, but really the only entity that has the power to realistically do them is the OEM - Valve could do it for SteamOS, but only on it's own hardware.
Given that a certain amount of windows gamers have been having issues making sure their PCs complied with the config requirements for the latest COD/Battlefield, it would seem an even higher bar for a consumer targeted bit of software that needs to do more to be running securely (or add a different mode to your distro install and reboot to it), alongside the wider variety of distros/configs. Distros advertising themselves for gaming or getting people to migrate from windows are also trying to keep barriers to entry low or to appear simple.
Thats the point to many things in life that you just make it more difficult and most people won’t be bothered to attempt to circumvent whatever it is.
There will still be circumventers but it is will be less than if you just said fuck it.
And if someone does the kernel bypass thing, well, rely on server-side heuristics (which are imperfect, but also unknowable to the attacker) and you'll discourage enough of that with account bans.
Helpfully eSports players tend to have video captures of their gameplay, and most of these "undetectable" cheats are real obvious if you actually watch the footage. That catches most of the serious stuff at the upper level. It's why video verification has been a thing in the speedrunning scene for such a long time.
Anyone can do that, but not anyone can simply “patch the kernel” and such.
Sure they can - download this pre-patched ISO and boot it in QEMU. Now you have a modified kernel, _and_ you’re not running dodgy spyware on your PC.
There's a subreddit called /r/vacsucks which is full of pro players blatantly cheating and getting away with it while the rest of the idiots think they're just good players.
Or, depending on your point of view, full of idiots flagging any player better than they are as cheating.
Aimbots can be "humanized" enough that any such determination becomes subjective.
That's assuming there's no money in being a cheater.
The real solution is to limit information sent to the client, make it harder for cheaters to have reliable solutions to get access to critical game information. ARC Raiders has Theia anti tamper (very poor performance) but right now the number of cheaters is minimal because the select few who are smart enough to break the anti-tamper are keeping quiet. See other examples; The Finals, Roblox (Byfron) and Overwatch
Yeah, I mean why would they open source their anti-cheats, would defeat the purpose, wouldn't it?
Not sure why you bring up OSS here, it isn't relevant in the least, plenty of non-OSS runs on Linux even though Linux and more is OSS.
If Linux did the same, anyone could recompile the kernel with their fake anticheat’s signature. The fake anticheat would then present itself as real to the game. One could go as far as to rewrite the relevant syscall to falsely indicate to the game that the legitimate version is running.
However that means that anything based on reaction times and such is impossible to protect against (under reasonable conditions). At the end of the day you can always have a robot sitting at your desk. But there is steps to that. You can have something that highlights enemies, etc., you can have something that controls keyboard and mouse (maybe inside a VM, so you don't need hardware) and so on. You can reverse engineer packet encryption in a debugger (in most situations) and have something on the network messing with stuff and so on.
So in that regard, yes you can prevent everything you can prevent on the server, but you cannot prevent every sort of cheating on the server.
Everything that has rounds basically can be prevented (other than again a bot playing).
Everything that is complex to automate is better, but might just make cheating more "worthwhile".
The other thing you can do on the server is "dumb cheat" detection. Eg. the odds of someone being consistently as good at a game and such. Statistics like that is widespread and doesn't need any change on the client.
- The game obviously needs to run as root, at least until large amounts of this stuff gets upstreamed into the kernel.
- We're going to be leaving the kernel and boot as untrusted, but injecting a hypervisor underneath the running kernel that is responsible for protecting most pages of game memory. This allows users to still run whatever kernel they want.
- The hypervisor sets up two sets of page tables, one that's only active when the game's thread is running and in userspace, one that hides protected pages and is active when the kernel or other threads are running. Note that game code itself needs to get decrypted into protected ram.
- The TPM of the system gets involved when we jump into the hypervisor to attest that the hypervisor is actually running, and the hypervisor then provides attestations to userspace that certain memory regions are protected from kernel or other thread access.
- Any syscalls will fail if they require the kernel to read or write pages that are protected. The game needs to allocate data that should be shared with the kernel into non-protected pages.
- When the game is closed, we can remove the hypervisor and Linux will be back to bare metal operation. This should be unobservable to the rest of the system.
This architecture preserves the ability of users to run arbitrary kernel modules, but does mean a hypothetical attacker can observe data that passes through the kernel (like draw calls/pixels). It's likely that a more complete implementation would also want some way for the hypervisor to attest to the accuracy of keyboard/mouse input and interface with iommu configuration like Windows KAC does.
As mentioned in another comment, you can’t do this on the server without expensive checks for every single player that is always checking line of sight, because it’s not just your session running on a single server but multiple sessions.
And let’s say you did this, now you have a latency problem because most modern games to make them feel fluid has client side prediction with server reconciliation. This is what makes your modern games feel more responsive, if you put a constant server check there you have lost this.
No matter what people say online, it isn’t just move all of it to the server, there is data the client needs to know and can’t be spoonfed by the server.
Why would a company pay for anti cheat infrastructure when they can outsource it to some company and blame them if there are cheaters or upset users? Windows is the status quo too, so it’s very easy to point to everyone else when justifying your choice to the execs.
It would be great if steam deck+box start costing studios quantifiable amounts of money that can be used to justify fixing this instead of outsourcing and hand waving.
I, for one am disappointed that anyone has accepted it. Once it's widespread, service providers can demand it, as we're seeing with mobile banking apps and game anticheat.
Personally, I run Windows purely for gaming and don't let it near any important data. For the latter, I boot into Linux with separately encrypted disks.
You can't suggest "run online games as close-knit social groups, with social exclusion punishments for cheaters", which is how most online games used to be run. How old are you?
Game vendors used to be happy letting us host and run our own multiplayer games, until they realised they could get more money out of us -- "battle passes", microtransactions, ability to forcibly turn off multiplayer of older game when newer remake comes out -- and now they've made themselves a mandatory part of your online experience. You have to use their matchmaking and their servers. So now it's down to them to solve the problem of cheaters, enabled by their centralised matchmaking... and their only solution is remote attestation of your machine and yet more data collection?
The correct solution is to verify everything server side, or actually have humans watch replays and ban cheaters, but both of those would reduce profits, so will obviously never happen.
Maybe add some blatant detection for people teleporting and doing other absolutely impossible things serverside, but I don't understand why my team has to ruin their 'reputation' teamkilling a cheater so he doesn't ruin the game completely in most current games when the anticheat only catches free, old cheats. Just let people votekick and find someone else in the matchmaking queue who's willing to join halfway through.. Once votekicked enough times you can escalate to the AI (always indians) for automated (manual) review.
Also, you don't even have to ban cheaters. Just isolate them to play with each other. Some might find it fun and keep away from the normal players.
Edit: The 'issue' with community server manual review and votekick is you can be kicked for being cracked or garbage at the game legitimately, but TBH at this point you're ruining the fun of everyone else, so you should probably get in another server/match.. Also that premades can have majority, but that's easily solved by reducing their vote weight.
Back in MW2 if you were the host you could kick players from your game using a cli tool that adjusted firewall rules.
I remember the misuse of it but it was better than having your only option be teamkilling, which is now punished in all games via reputation systems.
The only thing I don't see this as a solution for are games like Planetside, with massive lobbies. I know they used to have automated detection and manual review by admins teleporting and flying around, usually invisible to sus players. Once we found a bug and got inside the map able to shoot through the ground and in like 15 minutes an admin came, asked us how we got in there and to get out nicely, before he gets us out forcefully :D
If a==b, then everything moves on as normal. If not, the client gets a synchronisation error and has to rewind back to the last known good state.
Completely unfeasible for anything real-time pretty much.
You can always run things in a VM, you can always replace your keyboard and mouse with a different device, you can always have your a camera instead of human eyes and have something that recognizes enemies.
Even cheat detection in the real physical world (sports, chess, etc.) is not a completely solved topic.
You can connect computers to other computers so other computers will always be able to control them.
The idea that any (currently realistic) cheat prevention is unbypassable is silly.
The idea that anti-cheats don't make sense because they don't catch 100% of the cheaters is what's silly, who believes that? Not even the people writing these anti-cheats believe catching 100% of them are possible, why are you under the assumption that others think that's possible?
If it removes 80% of the cheaters from the game, the experience goes from "Holy shit lets leave" to "Ok, bothersome, but fine", this is what they're reaching for, not some fantasy utopia that you seem to be under the impression is the target.
This is making those rootkit anitcheat mechanism work. If people will leave, cheaters will play only with cheaters - problem solved.
Yeah, but it's a bit like the ultimately solution to climate warming; getting rid of all humans on the planet. Fine, it solves the problem, but who is staying to enjoy the solution?
There is also complete lack of secure boot and a way to validate that your kernel hasn't been compromised.
I mean seriously, making a cheat for a proton supported game that no anticheat has any hopes of detecting are in 100 lines of a kmod driver and 1 console command: insmod.
On windows you at least need to use scuffed tools like KDU to bypass signature verification requirements and every anticheat can detect you with a simple physical memory scan.
That's not true, though?
We are moments away from one of these "kernel-level anti cheat" companies getting hacked and then you'll have the biggest security scandal on the planet (if they aren't already hacked and we just don't know about it yet).