what kind of question is this?
steam does a dozen things to various games, much of it has been done before.. scanners, server client model, VAC bans, monitoring the leaderboards for strange values.. etc.
the update that occurred the last 24 hours, though, is a different thing. basically they are hooking the kernel32.dll apis, which are BASIC WINDOWS SYSTEM .dlls in nearly every program that launches on windows operating systems, and redirecting it to steam code that basically crashes the game if it decides that something it doesn't approve of is done to the game. For instance, a common thing that occurs is a .dll being injected into a process.
its quite easy to determine this is true by looking at a normal game that is not steam related and looking at the library addresses in the kernel32.dll and then comparing them to the steam run games and the same library addresses where we can see that steam has hooked those library calls and performed jumps to steam code.
as I said before, hooking windows system files is something that EVEN OUR TRAINERS DONT DO.. this is bordering on rootkit like activity or malware/viral activity. a bad side effect of this, that might not be intended, is if someone actually DOES have a virus and it does injections into processes that the user runs. suddenly all that user's games will quit working...
at any rate, this only leads to bad things the further down this path that valve goes in this. blizzard ended up eating crow after it banned people for hacking who had been falsely accused because normal programs or activities were flagging their software which was modifying windows api libraries as well as monitoring the list of the users files and scanning them, etc.. they stopped doing much of that..
I am all for multiplayer cheats being banned or prevented.. but this is destroying the fun of having a PC as compared to a console for games.. namely that you can mod your games or use enhancing software, etc.
I am also for trying to stop people from copying software illegally and sharing it. but once again, we see that the hackers crack these protections quickly and the only real sufferers are the legal users of the software.
I am going to go ahead and make the announcement that this move by valve will NOT stop multiplayer cheaters and will NOT prevent game cracking. what it MAY do is cause valve some possible problems in that they are modifying ACTUAL WINDOWS SYSTEM .DLLs running in a users computer without their knowledge or approval, as well as possibly setting up a lot of headaches for users who arent using trainers or ANYTHING but may have other software that causes steam to think they do and starts closing games automatically. also if they start logging stuff, many users will be banned or punished that have nothing to do with any sort of cheating..
my 2 cents..
the technical details are that steam game runs, check kernel32.dll, it has been modified at certain api call locations. simple as that... I have no idea if steam is doing this for anti cheat or anti copying of games or whatever. but this is a bad path to go down in my opinion..
not even close..
apparently so if you launch the game from steam..
maybe they wrote something about that somewhere in the 55 page user license you agreed to 5 years ago that they have updated 100 times.
keep in mind you don't own your games... just saying..
I get an occasional crash in UnEpic (switched to UnEpic due to Borderlands 2's CEG DRM preventing me from investigating further) in GameOverlayRenderer.dll's LoadLibraryA hook when the trainer for it attempts to initialize due to an invalid pointer being passed to stricmp, doesn't always happen though. Still investigating...
Edit: I am not trying to cause any strife here, I am genuinely interested in this problem.
[Edited by gibbed, 7/9/2013 6:28:59 PM]