I know this is looks like a "necro" behaviour, but this is important to read, if you had a two-factor authentication on Steam.
Every one knows how this two-factor authentication works (and you can read it up) so I'm not bothering explaining it, BUT there is something that not mentioned about it is that, when you have this TFA on your Steam account and updating your Steam on PC you get 2 file named ssfn"long number".
Now who are this guys: well this are "authorization file" and what are they stand for "Steam Sentry File (number)".
So why are you have them is because this file/s can be used to bypass all two-factor authentication so keep it safe and DO NOT give it to anybody.
There are number of posts on the Steam community about "phishers" using this files to hijack your accounts, so if somebody asking about your SSFN files, it's probably a Scammer/phisher, so send it to hell
Science WINS again!!!
Then they opened a portal to another dimension and kidnapping the locals.
The pissed locals are head enough and strike back.
and then... ALL HELL BREAKS LOOSE