Console port gone horribly wrong? I mean, how else do you violate the most simple of game rules - never trust the client?
Never trust the client
11–20 of 155 posts
Re: Never trust the client
#12"Never trust the client" is good advice for every kind of application. Clients are filthy liars.
Clients have bugs. Old clients don't upgrade. Packets arrive out of order. ACKs never make it to clients, causing clients to repeat what the client believes to be a failed operation. All of this is before even considering an attacker actively trying to subvert you.
The server should always be the source of truth. It should always enforce all the consistency rules. Database schemas can be a critical tool here as well.
Don't blindly slap whatever the client sends into a no-SQL database, then vomit it back out for queries.
Re: Never trust the client
#13Since this is a multi-player game this is obviously a big problem but I've always wondered how you'd handle this in a single player game with a leaderboard. Let's say you have a Bejeweled clone/match-3 game and a global high score board. What can you do to prevent fake scores? You can obviously obfuscate things, sign requests, etc but at some point the client needs to sign the score it's sending up so the client has…
You could send the score on a regular basis, and check to make sure it isn't increasing at an impossible rate?
Re: Never trust the client
#14Does anyone have a mirror for the "this is super bad" video?
I couldn't find it, but I did find a reddit thread with over video examples:
https://www.reddit.com/r/thedivision/comments/4gblza/hackers...
Re: Never trust the client
#15I doubt that the developer's didn't know not to trust the client - they likely made a business decision.
I (used to a lot more) play Elite: Dangerous. A space sim that has multi-player. They made the decision to use (mostly) p2p/client networking to save money - they wouldn't need nearly as many servers. This has caused other issues in addition to cheating - a low limit on the number of players in the same "instance" of the universe for example.
But it was a business decision - imo the wrong one, but what do I matter?
Re: Never trust the client
#16Console port gone horribly wrong? I mean, how else do you violate the most simple of game rules - never trust the client?
The irony is that the console versions are the least-impacted, as the client-side hacks are only loadable on the PC version.
Re: Never trust the client
#17Since this is a multi-player game this is obviously a big problem but I've always wondered how you'd handle this in a single player game with a leaderboard. Let's say you have a Bejeweled clone/match-3 game and a global high score board. What can you do to prevent fake scores? You can obviously obfuscate things, sign requests, etc but at some point the client needs to sign the score it's sending up so the client has…
This is actually impossible without hardware encryption. Apple should have no problem with this since they have control over their hardware, but they don't do anything to prevent fake scores from showing up in their leaderboards. Xbox is a great example of being able to trust the client. The console tells the server that it has unlocked an achievement by using a signed request which was signed by the secure chip. The same chip verifies that the games you are playing are legitimate, etc. It's a very important piece of hardware and it would likely be the Xbox's demise if that secure chip suddenly became insecure.
Running the game on the server is the only option as far as I know for securing the integrity of the data. You could add a private key to your app, but then you're shipping the private key to the client.
Re: Never trust the client
#18Since this is a multi-player game this is obviously a big problem but I've always wondered how you'd handle this in a single player game with a leaderboard. Let's say you have a Bejeweled clone/match-3 game and a global high score board. What can you do to prevent fake scores? You can obviously obfuscate things, sign requests, etc but at some point the client needs to sign the score it's sending up so the client has…
You could send events to the server (connected these gems, hit this target), and let the server calculate the score. Of course, that's subject to abuse as well. Short of hosting the game remotely, I'm not sure there is a solution.
Re: Never trust the client
#19Since this is a multi-player game this is obviously a big problem but I've always wondered how you'd handle this in a single player game with a leaderboard. Let's say you have a Bejeweled clone/match-3 game and a global high score board. What can you do to prevent fake scores? You can obviously obfuscate things, sign requests, etc but at some point the client needs to sign the score it's sending up so the client has…
IIRC in Puzzle & Dragons (one of the highest grossing F2P mobile games ever) the matches are purely client side, with a simple "I won" or "I lost" sent to the server after the match. I don't think it has leaderboards as a focus, which I bet is not an isolated decision. In general, the design of online games of any kind need to take into account all the potential issues & hacks and not be designed in a vacuum.
There's no universal answer to your question, but analysing behaviour of players and flagging various kinds of suspicious activity for more detailed inspection is likely the most common way. Designing the way to respond to such incidents is also non trivial, i.e. banning the player vs deleting the score, doing it quietly vs doing a large batch and prominently talking about it with the community, etc.
Re: Never trust the client
#20Since this is a multi-player game this is obviously a big problem but I've always wondered how you'd handle this in a single player game with a leaderboard. Let's say you have a Bejeweled clone/match-3 game and a global high score board. What can you do to prevent fake scores? You can obviously obfuscate things, sign requests, etc but at some point the client needs to sign the score it's sending up so the client has…
You could send the score on a regular basis, and check to make sure it isn't increasing at an impossible rate?
You can send the replay of client actions taken, including the random seed to be sure the board and subsequent random results are accurate. A bejeweled game probably represents a few KB of data in this format. Here's the seed, a list of which two gems were switched, and when special abilities were activated. Done.
Chess has a standard notation, and there's even tools to detect when human players are cheating by having chess engines play their moves by replaying parts of the game to those engines and checking for too many move similarities.