How to Wipe Out Deleted Files

[bostonman]

I tried using a hard drive file recovery program to see which files I deleted years ago. Unfortunately, I came across files containing important personal information that I deleted and hoped new files over wrote them. Obviously I don't want these files to be recovered again, and looking to wipe them from existance.

After research, I found a free program (which I already had) called CC Cleaner to wipe out deleted files. I ran it and currently doing another scan. So far the program has found many files implying CC Cleaner didn't wipe out everything. I'm uncertain why, I would think it would write junk files to take the place of the ones I want deleted, and then delete those.

Does anyone know how I can wipe out these files for good without compromising files that I want to keep? If a program is the best option, I'd prefer a free one.

[bostonman]

The file being corrupt was my thought, however, I was able to view pictures. Since the recovery software I am using is unlicensed, I'm unable to actually recover them, but allowed to preview.

[james_s]

When you delete a file, all that actually happens is the entry in the allocation table is removed, the data itself is still present on the drive until something else overwrites it. There are loads of secure delete programs out there, some wipe the entire drive but it sounds like you want the other variety which securely deletes individual files. They work by overwriting the file with random data and then removing it from the table.

Keep in mind some software caches things in other locations, web browsers of course, and things like Office applications auto-save, some media software creates thumbnails or copies data into a library so depending on what the files are and what you're doing with them there can be other copies in various forms scattered about.

[james_s]

That can be very dangerous when a novice is trying to nuke a few specific files and leave the rest of their data alone. Someone who is not used to Unix may be surprised by the way there is no safeguard or confirmation for certain commands. Years ago I once accidentally deleted the whole /bin folder on my work PC because I bumped Enter before I was done typing the path.

[bostonman]

This may be a silly question, or maybe it's too time consuming, but why can't a simple program be created that will write a large text file and keep writing until the drive is full, then delete the file?

[rdl]

As already said, you have to watch out for other software leaving traces of crap all over the place. If you use Windows, you'd be surprised how much stuff it hides in the registry, just do an internet search for "shellbags" for instance.

This is what I've always used on my Windows machine:

https://eraser.heidi.ie/

For reasons I don't remember, I continue to use an older version (6.0.10.2620). There must be something I didn't like about the newer versions.

[james_s]

This may be a silly question, or maybe it's too time consuming, but why can't a simple program be created that will write a large text file and keep writing until the drive is full, then delete the file?

There are lots of programs that do roughly that. I can't name any off the top of my head since I have not had a reason to use one in years and years but I'm certain there is no shortage of them out there.

[magic]

This may be a silly question, or maybe it's too time consuming, but why can't a simple program be created that will write a large text file and keep writing until the drive is full, then delete the file?

Yes, it works. I'm not aware of suitable software for Windows, on Unix you would simply cat /dev/zero >dummy_file or something like that. Much quicker and safer than nuking a whole partition. That being said, some systems may have quotas or reserved space which would prevent you from overwriting all free area on the filesystem unless special effort is made to bypass or disable them.

And there is a caveat about flash memories. On those, "overwritten" data may still remain alive in the flash chips for a while even if they aren't accessible from outside.

[james_s]

https://www.techrepublic.com/article/how-to-completely-and-securely-delete-files-in-windows/

[magic]

All those "shredders" and "erasers" are designed for spinning rust, too. When you overwrite your data on an SSD, the effect is the same as if you performed TRIM on them except that you are wearing out and fragmenting the flash by subsequently writing rubbish to it.

And of course it does nothing for files already deleted.

[0db]

At Google, they physically destroy hard-drives when they need to upgrade.

[magic]

Source?

Same Google that virtue signals about progress and ecology?

[bostonman]

BTW, these drives are not Windows drives. They were backup drives I copied files to. At some point I decided many files were not worth saving, deleted them, added new ones, and assumed the new ones overwrote any deleted ones that could be recovered.

[rdl]

BTW, these drives are not Windows drives. They were backup drives I copied files to.

"Windows" does not necessarily mean the OS is stored on them. If they use NTFS or FAT32 then they are generally considered "Windows" drives. Maybe you should consider some kind of disk encryption in the future.

All those "shredders" and "erasers" are designed for spinning rust, too. When you overwrite your data on an SSD, the effect is the same as if you performed TRIM on them except that you are wearing out and fragmenting the flash by subsequently writing rubbish to it.

And of course it does nothing for files already deleted.

SSD have to be treated differently, however for HDD Eraser can be used to securely overwrite all free space on a drive.

[SiliconWizard]

BTW, these drives are not Windows drives. They were backup drives I copied files to. At some point I decided many files were not worth saving, deleted them, added new ones, and assumed the new ones overwrote any deleted ones that could be recovered.

Whereas with conventional HDDs, the odds are pretty high that physical sectors containing deleted files will relatively soon be overwritten by new files, this is a lot less the case with SSDs wtih heavy wear-levelling algorithms. I think the odds of still being able to get ahold of the data in SSDs is much higher, at least if you can access the Flash chips at a low level.

I don't know if there are any tools that are *really* effective for permanently "erasing" all data on SSDs. If you know of one...

[Jr460]

Several "real" file systems have mount options to wipe file when deallocated.   It really slows down must system so you don't see it used very often.   Other filesystems will write zeros on allocate.

One thing you can do complete defrag your disk.  That will consolidate all he free space.   Then write a file of all zeros using all he free space.   hat should get things cleaned.   However as someone else side, if he OS has bits and parts in things lichee Registry, then you need to find something to clean that up.

Confidential or not, some places run a drive wipe program before disks are taken out of service.   They write a radon pattern over the whole disk, then all ones, then all zeros, then a different pattern.   In all about 7 passes.   It takes a bit to run.  If that is not done, then drive gets put in a degaussing machine.   In many cases after either of these, the drive is then crushed.

[Messtechniker]

By the way: when destroying HDDs it may be worthwhile to salve the very strong magnets within.

[magic]

I don't know if there are any tools that are *really* effective for permanently "erasing" all data on SSDs. If you know of one...

The closest standardized solution is the secure erase command. But in many (all?) instances it only involves generation of a new encryption key (all bits written to the flash chips are encrypted by the controller whether you want it or not) rather than actual erasure of data. You need to trust the hardware that it really forgets the old key for good and that it hasn't already leaked it somehow. That being said, it will work against a family member or similar attacker

One thing you can do complete defrag your disk.  That will consolidate all he free space.   Then write a file of all zeros using all he free space.

No need to defrag. Your dummy file would fill fragmented free blocks just as well.

[Ian.M]

I don't know if there are any tools that are *really* effective for permanently "erasing" all data on SSDs. If you know of one...

Otherwise the only hand tools^* that guarantees SSD data destruction are a Widlarizer and a medium mesh sieve.  Apply Widlerizer enthusiastically until the flash chip residue can pass through the sieve!

* A flowerpot full of Thermite cant really be regarded as a tool.

[bw2341]

This may be a silly question, or maybe it's too time consuming, but why can't a simple program be created that will write a large text file and keep writing until the drive is full, then delete the file?

I searched around a bit on the topic and even figured out a way using only Windows internal commands. Ultimately, I decided not to recommend them due to risk of data loss.

Instead, I suggest manually copying a large file repeatedly to the target drive to fill up the free space. In File Explorer, if you paste the same file more that once, the extra copies will be renamed automatically.

Choose a file that is 1 or 2 GB smaller than your system memory. That way, you can paste it over and over without having to reread it from the source disk.

If you are referring to CCleaner, it looks like it has a Wipe Free Space function. If you fully trust this program, you can give it a try. I have not tried this program myself.

[0db]

Same Google that virtue signals about progress and ecology?

Google crushes, shreds old hard drives to prevent data leakage Google offers new glimpse into data center security practices https://www.networkworld.com/article/2202487/google-crushes--shreds-old-hard-drives-to-prevent-data-leakage.html

[0db]

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Sources:https://www.schneier.com/blog/archives/2005/03/sensitive_infor.html http://www.cnet.com/news/the-right-way-to-destroy-an-old-hard-drive/ https://groups.google.com/forum/#!topic/digital-curation/n_f_bGQoNEc

[mrflibble]

https://linux.die.net/man/1/shred

[bostonman]

https://linux.die.net/man/1/shred

This will shred deleted files only and not current ones I want to keep?

[mrflibble]

https://linux.die.net/man/1/shred

This will shred deleted files only and not current ones I want to keep?

RTFM?

From TFM: shred - overwrite a file to hide its contents, and optionally delete it