Deleting Files/Folders On Your Computer

[winnie]

I don't know if this is known info to the common folk, but 2 devry grad students found out that deleting files from you hard drive and removing them completely from your computer WILL NOT DELETE THEM PERMENENTLY!!!

They bought 12 used computers and retrieved all the old files that prior customers deleted. They went on to say that the only way they are completely removed is if they are deleted and then over-rided with new info.

So, it looks like deleting info is not as safe as one would think. You must delete the info and the save new information in the same space.

[Commando_Barbi]

We have our computers at work checked on a regular basis. You are right. Even if you think you have deleted something...there could be temp back up files hidden away in places you don't know. They have some great programs to recover things you thought you got rid of.

[Mudge]

A drive is completely wiped out, when it is written with zeros (wiped out) 7 times. That was the standard at least within the last few years, generally at that level is when data can no longer be retreived. This is because magnetism will always leave a weak trace, just like on audio tapes that you write over, sometimes the quality of the recordings degrades with each overwrite because old "data" is left on the tape.

You can buy bulk tape/drive erasers which will speed the process, but even if you write over the old data with new, they can retreive it. Remember that deleted emails on a non-reformatted drive was how one of the senators or congresswoman was caught making ill remarks of Bill Clinton just a few years ago, I dont remember her position in the gov though for sure. You can actually find undelete programs, sometimes freeware, sometimes commercial, which will try to retrieve old deleted data. As a matter of fact one of the NT products is called UNDELETE. IBM has a freeware EXE called WIPE.EXE, which will wipe the drive writing zeroes too it (doesn't have to be IBM drive), so if you were really afraid do this about 10 times to your drive if your expecting a visit. Depending on drive size/speed it could take 30-60 minutes per drive, per pass.

I'm not a security guru, but a security enthusiast, and computers are my profession.

[winnie]

Originally posted by Mudge
A drive is completely wiped out, when it is written with zeros (wiped out) 7 times. That was the standard at least within the last few years, generally at that level is when data can no longer be retreived. This is because magnetism will always leave a weak trace, just like on audio tapes that you write over, sometimes the quality of the recordings degrades with each overwrite because old "data" is left on the tape.

You can buy bulk tape/drive erasers which will speed the process, but even if you write over the old data with new, they can retreive it. Remember that deleted emails on a non-reformatted drive was how one of the senators or congresswoman was caught making ill remarks of Bill Clinton just a few years ago, I dont remember her position in the gov though for sure. You can actually find undelete programs, sometimes freeware, sometimes commercial, which will try to retrieve old deleted data. As a matter of fact one of the NT products is called UNDELETE. IBM has a freeware EXE called WIPE.EXE, which will wipe the drive writing zeroes too it (doesn't have to be IBM drive), so if you were really afraid do this about 10 times to your drive if your expecting a visit. Depending on drive size/speed it could take 30-60 minutes per drive, per pass.

I'm not a security guru, but a security enthusiast, and computers are my profession.

Good info...thanks

[Mudge]

When you delete a file, actually what you are doing is removing an entry from your FAT (File Allocation Table). So basically this is like removing a pointer, this is why deleting files is much faster than making them, but the data that makes up the file is still there. With the pointer gone, your OS knows its safe to put data where "no file exists" even if its still there. But again, even if overwriting a file or reformatting the drive leaves a weak magnetic trace, plus there is no real way for you to know if you overwrote a file or not since the operating system controls where data is stored on the drive. I am sure some Unix geek has written a program that tells you in hexadecimal where on the drive data is, from what sector to what sector, similar to what you see when you partition a drive on a BSD box.

My brother had a drive go screwy on him recently, would no longer bootup. He had 2 drives on top of each other which makes for alot of heat, the data was still there but something happened to the FAT. FAT32 I think has 2 copies of the FAT, and NTFS has 5 (redundancy). With this, I used a program called Easy Recover Pro (you can find it on KaZaA ), to rebuild the drive using the data that was there, but couldn't be accessed due to the nonworking FAT. So even available to the public are software programs that can help retrieve "lost" information, but the feds of course can get down and dirty, and look at the drive with more sophisticated tools.

Some of these services are also available to the public, but retreiving data can cost as much as 5k or so, so it puts it out of the range for most of us citizens, and people that cared that much about thier data obviously have backups or RAID.

[Mudge]

Here is some interesting info:

http://www.pcedug.vic.edu.au/delete.htm

If the site is dead:

https://www.pcedug.vic.edu.au/delete...hl=en&ie=UTF-8" target="_blank"> http://216.239.37.100/search?q=cache:cWItvxPYI80C:https://www.pcedug.vic.edu.au/delete...hl=en&ie=UTF-8

http://www.computing.net/security/wwwboard/forum/2302.html

http://www.sysinternals.com/ntw2k/source/sdelete.shtml

The IBM file is wipe.com (component object model, like EXE)

[alwayzgrowing]

so i guess short of nuking my harddrive, shit can still be found

[alien8r]

good post

[chaos mage]

Big ass Magnet?

Remember the days when people would freak out when a magnet put next to their PC? Could you just keep a large magnet at home, and if paid a visit, put it next to your hard drive and corrupt it?

[alwayzgrowing]

Re: Big ass Magnet?

Originally posted by chaos mage
Remember the days when people would freak out when a magnet put next to their PC? Could you just keep a large magnet at home, and if paid a visit, put it next to your hard drive and corrupt it?

itz hit or miss. it may or may not do anything. probably not being the more likely ending

[Fina Addict]

watched a security guru segment on CNN and he said the only way to make sure no one sees whats on your hard drive when you get rid of it is to actually break the hard drive. That seems a bit drastic.

[winnie]

Originally posted by Fina Addict
watched a security guru segment on CNN and he said the only way to make sure no one sees whats on your hard drive when you get rid of it is to actually break the hard drive. That seems a bit drastic.

Makes sense...could you imagine seeing your neighbor run out of his house with his computer over his head, and then he smashes it down in the middle of the driveway. You would think he's friggen nutz. In all reality he's just doing a little "house cleaning."

[Drveejay11]

good info boys

[Mudge]

Re: Big ass Magnet?

Originally posted by chaos mage
Remember the days when people would freak out when a magnet put next to their PC? Could you just keep a large magnet at home, and if paid a visit, put it next to your hard drive and corrupt it?

Thats what the bulk erasers are, electro magnets of high power, because like said you will still leave a weak trace signal until you really do the deed several times.

[Mudge]

Originally posted by Fina Addict
watched a security guru segment on CNN and he said the only way to make sure no one sees whats on your hard drive when you get rid of it is to actually break the hard drive. That seems a bit drastic.

The problem is, that would mean taking the platters internally and breaking them, which means probably 30-60 minutes for Joe Doit Yourselfer to figure out how to get it open, and then procede to break the thing apart. Just throwing the hard drive wont do dick, as they can still get the platters from inside.