Originally posted by mblahnikluver
[..]
I have a question about stuff like this even stuff that isn't top secret. When you download a PDF or document, can it be deleted from your computer
if it's deleted from the original place you got it from. I don't mean to sound stupid I really don't know how all this works.
When you download a file to your computer, you're actually making a physical copy of that file. If you click 'Open' instead of 'Save', it will be
saved to a temporary directory - a directory that will be cleaned up at some point, for example at reboot. In both cases, the copy you made is
physical; it is now stored on your harddisk in actual 0's and 1's. Noone can remove that file without access to your operating system (e.g.
Windows).
I'm not too familiar with Windows anymore, but even though it has a history of backdoors and other gaping security holes, it should be absolutely
impossible for someone to delete your file by deleting the original. Normally, there are no connections whatsoever; the server you downloaded the file
from as well as your ISP may have a log of the download, but that shouldn't get them inside your computer.
Files can be deleted in two ways - either just the link to the file is deleted and the data remains intact until overwritten, or the link and the data
get completely purged from the harddrive. Standard operation for Windows is the first, so you might be able to retrieve your files through file
recovery utilities. Once again, I'm not up to date as far as Windows is concerned, but a simple freeware package like
this one might do the trick. The sooner you run it, the
better (since the lingering data may get overwritten by anything you do).
If the files truly have been intentionally deleted by a 'third party', then the best thing to do would be to protect your harddisk. Protecting your
BIOS with a password won't help too much, since either they'd be capable of doing this while you're online, or they have actually broken into your
home and thus can simply remove your harddisk from your computer and hook it up to a laptop - or whatever they want, really. So if you're going to
protect your files, it would be best to use a type of encryption. Even a simple zip file with a password would offer some protection. Once again
though, if there really is some third party with the capacity to get inside your harddisk, you might want to go for heavy encryption. Be sure to use
'low-profile' names for your files; when your files are encrypted, they may raise a flag just for being encrypted - but if they have obscure names
like 'privatephotos', they won't know what they're spending their encryption-cracking-time on, or what they're deleting. Considering the latter,
backups are always a good idea.
But first you might want to check how they may have gotten in. Your system should have a system log, in which every logon (either local or remote) is
stored. In Vista, you can get there (IIRC) through Configurations -> System Administration -> Logs. Select the Security log and look for special
logons. There is a lot of other stuff in there (such as logons by the system itself), so you may have to skim through the log a bit.
The best case scenario of course is to keep everyone's paws off of your harddisk, so make sure your firewall, antivirus and anti-spyware are working
as they should be and that noone but you & your trustees know how to get in (remove old accounts with simple passwords!).
Let me know if the file recovery turns up with something!