last I heard of this

[Blazikenowen]

it was a virus and a pretty bad one to

[Reifox]

There is NO virus, NO adware and NO malware.

[Mystix]

Steam/ Valve checks on their end for viruses on any files uploded by Developers to ensure they're safe and free of malware.

Though some anti-virus software might give a false-positive about Steam or programs (games or software) run via Steam.

For more info on that, see the Steam-support page at:
https://support.steampowered.com/kb_article.php?ref=4361-MVDP-3638

I'd also think that Developers who put their products on Steam hope to make a profit - which I'd say outweighs any need for malicious intentions. If a Developer did knowingly manage to upload something with a virus, and if it somehow got past Steam's checks, then it would look rather bad for that Developer, most likely ruining their reputation and probably getting themself banned from Steam as well.

[Auserna]

Last i saw of this it was VirtualGirlHD...

[ペンギン]

If a Developer did knowingly manage to upload something with a virus, and if it somehow got past Steam's checks, then it would look rather bad for that Developer, most likely ruining their reputation and probably getting themself banned from Steam as well.

That's naive to think. Depends on the goal. Should someone's target especially to upload some nasty stuff... they do not care about reputation or bans... and as we all known, adresses and all other data can be faked and developers/publishers change names like pants these days. There are several (one-man) companys which do exactly this.

Last i saw of this it was VirtualGirlHD...

Yes, this kind of software is kinda old. Gamecopyworld advertising as example...like how long? A decade or more?