As I understand it, Steam has a report feature on their store page for reporting games. Presumably that goes to a person that looks at it.

I think to upload games to Steam you also need to prove your identity. Which means if you do upload malware, then it's easy to track you down.

Of course, that takes time and things can slip through the cracks. Steam games are still full programs that run on your computer and can do anything a regular program can do, there's no sandboxing.

Treat them like you would apps on the Google Play store; assume that they're mostly safe but also give additional scrutiny to ones with low review counts or AI generated images.

IIRC, there was a recent case of a malware being discovered and quickly taken down.

I saw that it was not working properly on Wayland because it does not allow the game to record keystrokes from other apps.

I did not know Wayland did this. That's awesome.

Rare time seeing the Wayland Feature protecting you from keystrokes.

I understand that Steam probably has a robust mechanism for understanding game behavior

I mean maybe they run your game in a monitored environment and record what kinds of things you do behind the scenes, but that's a lot to ask for for every game uploaded. I honestly very much doubt it.

They may not remove Nazi communities but anecdotally they seem to remove malware quickly. I do suspect though that there is other iffy software on steam so do pay attention.

Gaben would come to your house and arrest you.

There are two cases.

When you run a game, the game is allowed to monitor your input (up to some configuration), so you shouldn't e.g. open a game and do online banking at the same time.

When the game installs a malicious software such that your input is monitored even when you're not running the game, then you can only rely on the additional defense mechanism. However, this is similar to all other software.

In general steam is going to run a .exe for a game, and as such that's really going to be able to do anything a user process can do under windows (or linux if it has a dedicated linux binary). Steam doesn't run games inside a sandbox. That includes prompting the user to elevate the process to admin, and if the user clicks yes, being able to do anything an admin level process can.

There may well be some pass/fail testing before they will list a game, and for sure if there were reports showing a game was doing something malware/illegal they would certainly investigate/remove games that breach this.

But, steam is not a protection in and of itself.

This got me thinking; how does Steam protect us from malware?

In the sense of isolating games like a mobile app is on a mobile OS or something? It doesn't, not as it's installed normally. If you can do something, the game you're running can. Steam doesn't isolate individual games, and Steam is not, as it's normally installed, isolated.

Wayland won't let a random window on the screen see keystrokes going to others, but because the games aren't normally running in isolation, they can fiddle with the environment such that they can do whatever. Wayland's "keystroke" isolation is only useful if the software also can't muck with your files; it's intended to be used in conjunction with other forms of isolation.

I understand that it's possible to use Steam packaged as a flatpak, which will isolate the Steam environment as a unit, including Steam and games.

investigates

https://flathub.org/apps/com.valvesoftware.Steam

Steam is potentially unsafe

• User device access
  Can access hardware devices such as webcams or gaming controllers
• Music subfolder xdg-music
  Can read all data in the directory
• Pictures subfolder xdg-pictures
  Can read all data in the directory
• User runtime subfolder app/com.discordapp.Discord
  Can read and write all data in the directory

Assuming that those are the only filesystem permissions it has

and I don't have experience with flatpak, so I wouldn't use me as an authority

then it should prevent anything in the container from doing things like grabbing SSH and GPG keys, stuff like that. A malicious game in the flatpak could still grab your Steam credentials or information from other games and muck with those.

• Legacy windowing system
  Uses a legacy windowing system

Not an issue if you're using Wayland, since it'll be using xwayland, which itself is isolated.

• Network access
  Has network access

You cannot deny network access to the flatpak, as Steam will need that to work.

Some Steam games can be run outside of Steam, don't need to talk to it, and for those, you can explore other isolation options. Can maybe cut off network access using firejail or something like that.

• Microphone access and audio playback
  Can listen using microphones and play audio without asking permission

• Proprietary code
  The source code is not public, so it cannot be independently audited and might be unsafe