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  1. #1
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    Enhanced hard drive erase, how?

    "smartctl -a" reports an enhanced erase feature as enabled on some of the newer hard drives. It lists times required to securely erase a complete hard drive as "184min for SECURITY ERASE UNIT". There's little info on how to activate it though, clues?
    bigwrench

  2. #2
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    I've never heard of that before

    Maybe it just means newer drives are faster at writing zeroes over a disk and it gives you an approx time?

    Simplest way to flaten a drive is to run dd if=/dev/zero over the disk

  3. #3
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    What you describe is new to me as well.

    In the past I've used this https://computing.llnl.gov/linux/scrub.html to securely erase disks by mounting the disk on a new machine and scrubbing the device.

    Note that just writing one pass of zeros over a disk, while it may serve most purposes, is not a good way to securely scrub it.
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  4. #4
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    Note that just writing one pass of zeros over a disk, while it may serve most purposes, is not a good way to securely scrub it.
    Agreed, but for a general purpose wipe it's "quick and dirty"

  5. #5
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    Quote Originally Posted by PCS-Chris View Post
    Agreed, but for a general purpose wipe it's "quick and dirty"
    Haha, Indeed
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  6. #6

    Secure Erase

    Secure Erase is a part of the IEEE ATA specification and is a standard component of all standards compliant ATA based devices since 2001. The feature is called Secure Erase and is initiated as a command level process by presenting the controller with a predefined sequence of commands necessary to initiate the process. The process is defined by the NIST in their special report 800-88 as a purge level process, providing the same level of data elimination as degaussing; and more effective than CLEAR level processes such as software based overwrite technology.

    The process runs as an internal process and therefore is able to benefit from privileged access to the drive controller operations. This permits SE to purge not only the commonly accessible data storage regions, but also G-List sectors, and if launched properly, the Protected service Areas, including the Host Protected Area (HPA) and the Device Control Overlay (DCO), essentially, all data storage regions on the media surface. It is important to note that NO software or external overwrite based product can effectively eliminate all data on all data storage sectors of the media surface. SE is also very efficient, and can process a device at a rate of ~35 minutes per 100 Gig. Compared to a triple pass overwrite initiated from an external application at a rate of 6-8 hours per 100 Gig. Clearly SE is far more effective and efficient.

    So? why don't we see every software vendor hopping on the SE boat? Well, this is a great question... SE is very powerful, once launched, it can not be stopped until completed. If the device is disconnected or powered down mid-process, the device will need to be reconnected and the proccess continued before the device will present itself as a usable volume to it's host. So, if SE were to be exploited by a virus or malware, the consequences would be devastating. In order to mitigate this vulnerability, most hardware vendors have incorporated hardware and BIOS level protection inhibiting SE from being launched in their equipment. This means that in the majority of hosts, SE can not be launched reliably. Therefore, making any software based utility unreliable.

    The only way to effectively initiate SE is with an appliance that does not incorporate these hardware and BIOS based limits. Such appliances are available from a couple of manufacturers, some are more reliable than others. The unit from Ensconce Data Technologies (deadondemand dot com) covers the widest range of devices.

    I am a co-author on a paper titled 'The Best Practices for the Destruction of Digital Data' a guide written to provide policy developers with the necessary information to develop effective security policy for the management of end of life hard drive storage devices, using current and valid guidance. The paper is based on my research and is currently in use by a number of government and private sector organizations as valid reference on the topic.

    Anyone interested in this comprehensive 55 page guide is welcome to fill in the request form on the bottom of the NEWS page at converge-net dot com web site in on the ENGLISH section.

  7. #7

    Secure Erase

    One last comment... SE was developed at the University of California San Diego's Center for Magnetic Recording Research. The CMRR had published a Proof of concept utility called HDDERASE.exe this utility is not meant to be a production utility and is very limited in its operation. Although it has been offered up by a number of freeware sites as a means to launch SE, it is limited ot the first IDE channel, and will not do the PSA's onthe drive.

    You can manipulate the system to have HDDERASE recognize the SATA or second IDE channel, but please be aware, it is hit or miss.

    Remember, this is a Proof of Concept utility, it was not meant for general use.

  8. #8
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    Welcome to WHT fedelst. Thank you for stepping in with the right stuff about SE.

    The SE feature caught my eye for its ability to wipe an entire disk drive in far less time than with current tools. Such a feature is increasingly necessary as disk drives get into the multi-terrabyte range while transfer rates remain unchanged.
    bigwrench

  9. #9

    Secure Erase

    Agreed, and this is the challenge. Finding a reliable means to eliminate legacy data on large volumes gets tricky. No one wants to invest a week or two having to run a multipass overwrite process on a 1TB device. The cost of the operation is greater than the value of the asset, or the time to process.

    Other processes such as degaussing although effective when done properly, can be a game of cat and mouse. As new higher density devices come to market, the amount of energy to effectively achieve coercion on the media surface increases with advanced media chemistry. Ultimately, the investment in appropriate hardware to degauss a high capacity drive will require an investment of greater than $60k, and adequate operator training to assure proper use.

    Considering the compliance implications of improper data destruction and the disks imposed by using off site or third party data destruction services, we are seeing a trend in both the public and private sector to favor the use of onsite data purge appliances for the on-site processing. Any device that contains sensitive information that are required by policy to be physically destroyed are then sent to a centralized destruction facility after the on-site process. By adopting this protocol, should an asset become lost in transit, the event would not result in unintentional data exposure.

    Clearly, the creation of effective policy required the inclusion of many considerations.

  10. #10
    I like the shredders that wreck a hard drive pretty good!
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  11. #11

    Shredders

    I do too, it is pretty amazing watching a drive get crunched up into tiny pieces... However, this is not acceptable practice if you are handling data classified to secret or top secret levels.


    Yes, the drive may be shred into tiny bits, but when dealing with information that has high classification levels, the process must eliminate data beyond recovery using current or future technology. Accordingly, the media must be ground to a screening size smaller than the smallest recoverable element, which would be a single data sector. This would require the particles from the media to be no greater than 1/250th of an inch. So, that chunk of media that came out of the shredder may actually not be compliant to some regulations.

    This spec had been 1/125th of an inch up to March 2009, when it was determined that the density of modern high density media had in fact reduced the sector area to the new size. This was an easier spec to deal with as many shredding facilities could accommodate this screening size. The current spec can not be attained with most commercial shredding equipment. In order to address this need, the use of a purge process before the device is submitted for destruction can accommodate most concerns.

  12. #12

    Does the process auto-restart

    Quote Originally Posted by fedelst View Post
    SE is very powerful, once launched, it can not be stopped until completed. If the device is disconnected or powered down mid-process, the device will need to be reconnected and the proccess continued before the device will present itself as a usable volume to it's host.
    Would the process automatically restart after the machine was started up again or does it have to be manually restarted with the command than ran it originally? E.g.
    hdparm --secure-erase .....


    Stu

  13. #13
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    Thanks for the info fedelst!

    I'm currently studying for a master's degree in Information Security at the University of London, so I'd definitely love to take a look at your paper. I'll send you a request from your site.

  14. #14
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    Quote Originally Posted by e-Sensibility View Post
    Note that just writing one pass of zeros over a disk, while it may serve most purposes, is not a good way to securely scrub it.
    I personally disagree here. Writing one pass of zeros is a secure way of deleting data (although potentially not relocated sectors). Writing bytes multiple times, or varying bytes, seems a waste of time to me. If you're talking genuinely top secret government data, maybe not, but the cost of attempting to recover any amount of data would be extreme to say the least.

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