Secure deleting of files on MBL

Does anyone know how to do this? I’m after a utility that could do a secure overwrite of particular files on the MBL. Happy for command line/ssh if needed…

I do not know of any, but the OS on the MBL is Debian Lenny. You mght be able to find something for it.

astrodog wrote:

Does anyone know how to do this? I’m after a utility that could do a secure overwrite of particular files on the MBL. Happy for command line/ssh if needed…

the command ‘shred’ does exactly what you want.   It is part of the MBL’s basic O/S.

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Thanks - it was right there all the time!

You can download Eraser for free on a windows system. The built in shred handle for Lenny is not a secure method because it leaves track headers fully intact.

If you do use Eraser, be sure to select an eraser method of 7 passes or lower because the ones stronger than that need an SSD to make it acceptable in terms if time scale. Eraser will scan and erase headers if you select that option as well as erasing whatever free space there is on the drive (because windows doesn’t delete that, it just marks it as available for rewriting in future).

Eraser can be scheduled, you can create schedules for certain folders to be erased. Very good piece of piece of free software, and to put your mind at ease it uses various military grade methods for deletion and if your are extremely paranoid there is a eraser method which exceeds military methods by large factor by doing 35 passes, changing every 0 to a 1 and every 1 to a 0 and then uses an algorithm based on the file name, hexadecimal name, file size in decimal and date of creation to change the position of all 1’s and 0’s… 35 times. Then it changes them all again to 0.

Highly recommended for everybody in community because it will do this for network drives, but when the data is erased it is erased. No company out there will ever be able to retrieve it even if you deleted the wrong file and wanted it back. It will truly be gone forever.

ProjectVRD wrote:

Highly recommended for everybody in community because it will do this for network drives,

Impossible.

Samba has no such hooks to allow such a guarantee of “secure erasure” for network drives.

Even Eraser’s FAQ says this – they don’t guarantee security using this on network drives.

Even Eraser’s Developers say NO!

http://eraser.heidi.ie/forum/viewtopic.php?f=2&t=6037#wrap

 … unless you’re talking about some other software…

Same software, if you use Eraser via the mapped drive for the My Book Live you are utilising the windows operating system, the computers processor and the NAS’s HDD. I have tried retrieving the data myself (I work on IL3 systems and my job encompasses security) and for this product, Eraser works as intended.

But it must be used to delete what it sees as the mapped drive, run on the windows operating system. It cannot be run from the My Book Live and I wouldn’t do that anyway even if possible, it burn out the board trying to run the algorithms locally on the NAS.

Give it a go and see, there are very powerful recovery tools you try but we use enterprise tools and third party companies they never succeed nor do they report finding any traces that allude to prior existence of the deleted data.

I think you need to read that whole thread again.

Particularly, the developer’s warning that…

“You’re running this at your own risk. Eraser works on the assumptions that David stated in his posts and in networked computers/drives the assumption may not hold. For networked computers, it may still work, but don’t take my word as gospel.”

What did David say?

“Eraser is designed to run on the operating system which is directly hosting and controlling the drive. This is difficult with a NAS.”

Windows connects to the MBL using CIFS.  CIFS has no such capabilities to do block-level hard disk access, which Eraser REQUIRES to guarantee total erasure.  The operating system isn’t even aware of “blocks” or “sectors” when accessing network storage.   It’s just dealing with file handles, bytes, and offsets.  The host OS does everything through an abstraction layer which completely obfuscates the drive’s actual content.

I would be _ astounded  _that an IL3 security audit would “pass” such a workflow, especially when the developers of the tool say Don’t Do It!

Using security products in a manner that is contrary to specifications / documentation is just an incredibly risky practice…

ProjectVRD wrote:
…we use enterprise tools and third party companies they never succeed nor do they report finding any traces that allude to prior existence of the deleted data.

The most you can conclude from this is – you got lucky.  

Eraser says don’t use it on SSDs or network shares – that’s enough for me to say “no way.”

That’s fine, you don’t have to use it. But it has been tested and it works. You get nowhere in life without testing and looking at some of the advice given on this site this is a small risk test compared to making the actual firmware perform tricks it wasn’t designed to for.

Besides you ask what he said? He said the OS had to control the device, and when it running the Eraser process it is. I have told you it works, and consistently, you don’t need to try and prove me wrong but if you feel it is necessary then you are welcome to. Somehow I don’t think you will though given your resistance to any solution other than your own (that is how you are coming across here).

The OP wanted a secure deletion method, I gave him one. It also works perfectly on SSDs. If the OP wants to leave traces he’ll use your solution, if he wanted to securely delete files and folders he’d go for the option I provided that actually does the job properly.

This wasn’t a case of being lucky. It is a case of testing, analysing, retesting, analysing etc. Much like all the tricks that can be found in this very same forum. So, now it is clear we are light years away from seeing eye to eye on this, it is best to just agree to disagree.

ProjectVRD wrote:
Besides you ask what he sad? He said the OS had to control the device, and when it running the Eraser process it is.

I am sorry, but your conclusions are based on a completely flawed understanding of how NASes work.  The windows system running the Eraser program is NOT at all in control of the disk in any way, shape, or form.  The system running onboard the NAS is in total, complete, and irrevocable control of the HDD at all times.

Your insistence to the contrary will only reinforce the developer’s caution.

And as to SSDs:  again, that is impossible.  Simple wear-leveling logic inherent to most SSDs prevent overwriting sectors in a predictable manner. Only complete physical destruction can guarantee it.  Again, the SSD developers agree…They even warn that trying it will substantially  shorten an SSD’s life.

http://eraser.heidi.ie/forum/viewtopic.php?f=2&t=8820

Sorry, but for a security expert, you are giving very dangerous advice.

The shred function is weird - if you do it without the -u argument, it seems to erase the files data, and leave an empty file of the same name on the drive… why you want to do that is beyond me?

Using it like:

shred -u filename

Seems to give the desired effect, I’m not hiding traces from any 3 letter agencies, just nice to be able to properly blow away personal stuff from prying eyes… and even then not so important, as I try and keep anything important in encrypted volumes…

astrodog:  shred leaves files in place for very specific reasons (such as /dev/hdx)

shred /dev/hdx would shred the entire disk, but not remove the special file (which only refers to the disk.)

Like the much-touted Eraser program above, shred has some limitations, particularly with EXT4 Journaled file systems.  Make sure you’re aware of these…

The MBL uses EXT4 in ORDERED mode, so just be aware of the distinction.