Something maybe spies out Firefox

[1likenooneelse]

Hello
I ran TestDisk and PhotoRec on my home dir just to see what for deleted files i have on my computer, there i found some strange screenshots of my firefox sessions, which i am pretty sure that i never made them.
They were .png in 455X256 dimension and show the sites without the window decorator if this helps, and i run my firefox as "portable" not installed folder out of my home and i have no other plugins then a pdf to file printer, https: everywhere, and of course add block plus and download helper, so nothing should or could make screenshots by accident i believe!
Even more strange is, that after i cleaned those deleted files, with bleachbit as admin, there were (besides alot of .xml) showing up two new .png screenshots which were pretty new(same day), but that old, that they should had to show up with the first scan i made(I know, PhotoRec is not perfect, but that is not the point that makes me wonder).
Yeah, so i thought, maybe firefox makes them for some reason, so i searched for .png in firefox directory(My portable fox has bins and configs in the same folder) after surfing a while, but there is nothing!
Now my question is, does anyone know something about, does firefox such screenshots for some reason and deletes them, or could that be a new form of these java spy trojans(I never clicked and accepted something, so it is not likely but we never know these days)?
By the way, i also found some .jpg which contained many little pictures of music vids content i watched and downloaded on youtube and afterward viewed with vlc.
I bet, these were just from the new flashplayer preview function, but why to hell they put that to my /home and not to /tmp (Which i made tmpfs for more speed) or could it also be some kind of spying trojan?

I have nothing strange in my System-Monitor as far as i can tell!
By the way, can any PRO give me a very good link on how to detect boot/rootkits manually(i bet this is not even possible, am i right?), since there is still no useful software for linux(To all those "Linux is save" and "In God we trust" people: PLEASE keep these stupid opinions for yourself!)
I am on Mint 13Mate, but that says nothing, since i had to change alot to make it usable and bug/limitation free....It was somehow a shame for an LTS(just piss on release expectations of users and make it perfect next time... like mint9 was), also and maybe mostly on Ubuntus side...

[karlchen]

Hello, 1likenoonelese.

Not a manual approach, but how about getting rkhunter and chkrootkit from the Ubuntu repositories and having them check the system for signs of rootkit infections?
Also you may like to make sure that your users have got decent passwords that cannot be guessed easily. In particular root shoudl have a strong password or the account be locked completely (like on Ubuntu).

About left-behind Firefox screenshots in thumbnail size: Well, just checked it. There are 2 such thumbnails in the thumbnails subfolder of my Firefox profile.
If you are really concerned about your privacy then you should instruct Firefox to cleanup everything on exit. (Preferences => tab "Privacy". Tell it to delete the history on exit. There is another "Preferences" button next to this option where you can specify in detail which things Firefox should delete when exiting. )

Kind regards,
Karl

[thegreatgazoo]

I don't use Firefox, but I believe that like Chrome, Firefox has a landing page with small pictures of your most visited sites. You are probably just seeing the screenshots that it generates for the previews.

Sent from my Nexus 4 using Tapatalk 2

[bjornmu]

Yes, firefox make those thumbnails to show you when you open a new tab, as suggestion for where to go. hit CTRL-T and you should see them.