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Comment by crsv | Hacker News Reader

This is a great technical breakdown of some modern high level approaches to common cheats. I think this the most transparent approach (even though the author admits leaving some detail out) to modern anti-cheat for massive multiplayer games. Good on riot for having an open dialogue about this. I don't think you'd ever see someone like Valve going a transparent route with something like this. (Not making a judgement on that decision, just an observation).

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Fair context: I make cheats/utilities this exact game being talked about in this article, so perhaps my opinion on the subject is biased or even invalid.

I partially disagree about the transparency of this article, while they do explain most of their approach to anti-cheat (and that is pretty cool for them to do), they seem to leave out any mention of anything that could be controversial.

It suppose that it does make sense to not mention the implementation details of their anti-cheat, but I wish that they would be a little more transparent about how/when/what they snoop around and send to their servers. The current Mac game client for League Of Legends contains full debug symbols and it doesn't have Packman (the packer described in this article), which makes it quite easy to look through the symbols. Inside you can find all of the anti-cheat-related network packets, in specific:

PKT_C2S_EnumDrivers PKT_C2S_EnumProcesses PKT_C2S_EnumDrives PKT_C2S_EnumHandles PKT_C2S_EnumRecentFiles PKT_C2S_EnumModules PKT_C2S_ProcessorData PKT_C2S_SystemState PKT_C2S_ModuleLoadNotification PKT_S2C_SendModule PKT_C2S_ModuleResponse

Now, I personally expect anti-cheat to snoop around my system when I'm doing something shady like scanning its memory. However, if I was a normal user of the game, I would be a bit concerned to know that it might be sending my recently used file names, drive names, system driver names, currently running processes, processor information, system state, and even entire binary files that it automatically deems as "suspicious", to their servers.

Do you know if process information contains command-line information? Because that could totally contain someone's credentials...

Which is precisely why it is an antipattern for any program to pass it accept credentials as command line arguments.

I wasn't endorsing the practice.

Wouldn't that run afoul of GDPR?

The anticheat team at a videogame company might not know/care about this. This has definitely been the case with past European data privacy regulations.

Or it might be deemed reasonable. E.g. you may not film public road in the Netherlands because of privacy, but you may film the patch that your car stands on it if there have been car fires in your neighbourhood in the past month and you are concerned about your car.

> you may not film public road in the Netherlands because of privacy

So does this effectively make dash-cams illegal?

License plates contain personal data.

Not necessarily. GDPR isn't a blanket ban on collecting/using this info without consent, it's a policy that consent is required for non-essential collection/usage. You could argue that anti-cheat is essential for an online multiplayer game like this.

I think it's sketchy to collect this much info, but I don't think it's explicitly illegal.

It's a bit more complicated than that. You have to do a few things. First you have to tell the customer that you are collecting their data. Then you have to tell them under what lawful basis you are collecting their data. The user then has various rights (depending on the lawful basis you choose) to object, etc. If you must collect and use the data in order to fulfil the contract (i.e., there is no other way to do it -- for example you need to get their address in order to ship them a package), then you can just do it (as long as you tell them that you are doing it). For most other lawful bases, you have to allow them to object, in which case you have to stop using the data.

I think the real question is whether or not the information in question is personally identifiable information. If it's not, then GDPR doesn't apply. I think you could make a pretty strong argument that it doesn't apply, as long as you take pains to ensure that you can't identify the person from the information.

> I think you could make a pretty strong argument that it doesn't apply, as long as you take pains to ensure that you can't identify the person from the information.

That would entirely defeat the purpose of an anti-cheat system. You have to have some sort of personally identifiable information attached to the data being sent in to the server, otherwise how are you going to ban the cheaters? Even IP addresses are personal identifiers as far as the GDPR is concerned and even if they're not storing it long term, just sending the user data over the wire is enough to trigger the data collection portions of the GDPR.

Exactly this. The moment you send it via IP you have the IP address and therefore have PII data. And the moment you take screenshots you cannot not be sure what you collected.

This does go further beyond GDPR as it is imho an intrusion into the inner most personal space. I believe a German court of law would have a field day ripping this practice apart, if a case would be presented.

Esp. if they do not totally make it clear upfront what they are doing. In a way every layman is able to understand.

Instead of using an IP address to identify cheaters the game could assign a unique random generated ID to players. Then they could ban that id without using IP. I think this scheme complies with the GDPR if you take care of not binding that ID with other user personal information.

If you can identify a physical person with a unique identifier, it is PII according to GDPR, I believe.

You can apply a one way function to an IP to obtain an ID and then maintain a database of bad IDs. For example you could compute this ID by the SHA256(IP + secret salt). Since way one function don't allow you to recover the IP, the ID is not PII. If you detect an IP which has bad ID the connecting ban that IP from the game. I think this respect the GDPR, you don't maintain a list of IPs or any other PII.

I seriously doubt you'll be able to cheat the courts with silly tricks like this. SHA256 isn't any different from ROT13 here.

Any phone has enough computing power to just bruteforce a 32bit value in order to recover the original IPv4 address from a normal cryptographic hash in a practical timeframe.

The second you use this ID to tag data you're sending over to the servers, that ID could easily lose any claim to anonymity for the purpose of the GDPR because the anti-cheat system vacuums up a vast trove of information. All it takes is one email "Re: Claim for Your Local Psychiatrist Bob" or a document named "John Doe Jr - First Grade Book Report.docx" showing up in the titles of your open windows (that many anticheat systems send to a remote server) and boom, that ID and all of the data attached to it are now a radioactive liability.

> The current Mac game client for League Of Legends contains full debug symbols and it doesn't have Packman

Probably because the person writing these anti-cheating facilities isn't as aware of how to implement these on macOS.

Unlikely. More likely there's simply not a very large Mac player base for the game, as compared to Windows

>even entire binary files that it automatically deems as "suspicious", to their servers

If "deems as suspicious" means "whatever the server tells it to send" I would be very concerned.

How do they know you're not doing something shady if they don't actively scan...

Why do you think they have the right to know whether I'm doing something shady? Are they some kind of police? Did they get a warrant?

I don't expect software I use to scan my hard drives and exfiltrate data ("send samples") to their developers. That's exactly what malware does.

Companies just say it's for "security reasons" as if that somehow justified everything. When I read an anti-cheat software's privacy policy, I discovered it could scan my RAM, my files, take screenshots... They're basically trojans. It's not just game companies either. Banks here trick users into installing "security modules" that are actually kernel mode network monitors. I refuse to accept that.

These shady anti-cheating practices makes cheaters look good in comparison; similar to how copy protection measures make a genuine product inferior to the cracked version. If a hacker figures out the game's network protocol and writes his own client, he won't have to install a bunch of malware on his machine just to play the game. In my opinion, these developers are the real heroes.

So are you living out of that?

Valves John McDonald recently gave a talk at Gdc how they use machine learning to combat cheaters in CS:GO. Quite interesting to watch. https://m.youtube.com/watch?v=ObhK8lUfIlc#

Is this really open dialogue? Correct me if I'm wrong, but basically all of the methods that they mentioned are pretty standard stuff. They had a few interesting twists on these ideas, but in general, things like source code encryption and shuffling memory locations seem pretty basic.

if you are familiar enough with the subject matter everything will seem basic.

Well I have to agree with op. Encryption and obfuscation started with early copy protection systems, even packers like upx offered that iirc. Measurements against memory manipulation have also been around for a while, I encountered them the first time when I tried cheating money in rollercoaster tycoon in 99 or whenever that came out. Obfuscating the network protocol actually seems more of a novelty than those two things.

It's a good article but I'd hesitate to call this "modern"; this is circa-2006 AAA title security. Serious content protection is significantly more sophisticated than this.

(I'm not an expert but I've done some anti-cheating pentests before, and have seen literally all these primitives deployed on old titles).

Most anti-cheat methods stop working once the details are known. As someone else mentioned, there was a talk at GDC this year about one of their anti-cheat systems. The talk got into a lot of detail about how this particular system worked.

Because they all do the same so there is no need to share that. Riot is a recent studio, other studios have been doing that for years. As for transparent approach I'm not sure what you're referring to, players don't need to know that kind of things, there is no benefit sharing that to the public.

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