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Thread: Sanitising a computer remotely

  1. #41
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    Quote Originally Posted by killadaninja View Post
    This is what i ment when i wrote fill the files with 0 `s,
    Exactly, I was simply agreeing that this would be a better method than to overwrite the file with an empty version.
    -Monkeys are like nature's humans.

  2. #42
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    The newest version of dban comes in a USB version which can be set to run a autonuke on boot.

    The only issue will be enabling lilo which may trigger an alert from the AV.

    Edit:

    Link from dban webpage: Use Heidi Eraser for file wiping within the Microsoft Windows environment.

    Quote Originally Posted by Barry View Post
    There's probably a way to get dban to run on boot. It runs in memory, so once it's running it won't need the drive anymore. Though it's already been said, the info has probably been pulled already.

  3. #43
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    In the future I recommend that your client protects itself by using some anti theft software such as Computrace...

    I have no experience with any type of this software, but it's supposed to make it easy to automate deletion of sensitive files in a timely manner in this situation. If you utilize full disk encryption in addition to this you will have comprehensive physical data theft protection for your laptops, assuming you prevent your users from using Suspend/Hibernate via GPO and they don't leave their laptop powered on all the time.

    As a side note... It seems you guys are way too late on wiping this laptop, unless the user is as stupid as we think. What's to prevent him from making 100 copies of the data by now? Do you have some sort of USB / CD access control? Either way you have his IP address and if you find that he used the data you can have the feds up his ass in a heartbeat.

  4. #44
    Very good friend of the forum Virchanza's Avatar
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    Let's imagine you used Truecrypt to encrypt the entire hard disk. The user has a password such as "monkey", but there's also another string that gets appended to it, and this string is stored on the hard disk. This extra string might be "backtrack". So to decrypt the Truecrypt volume, the password is "monkeybacktrack". The computer can have a countdown clock that destroys the "backtrack" password stored on the harddisk. Everytime you connect to the internet, the countdown clock gets refreshed to 1 week. So if the computer were to disappear and never be seen on the internet again, it would still time out after 1 week.

    By the way, another way of doing this is by having the delicate data on a remoter server accessed by remote shell, but that's not practical if the person has to work in the arsehole of nowhere where there's no internet for hours or days on end.

    Quote Originally Posted by komseh View Post
    Either way you have his IP address and if you find that he used the data you can have the feds up his ass in a heartbeat.
    It still bemuses me when Americans think that the law enforcement of the USA encompasses the entire globe
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  5. #45
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    Quote Originally Posted by Virchanza View Post
    Let's imagine you used Truecrypt to encrypt the entire hard disk. The user has a password such as "monkey", but there's also another string that gets appended to it, and this string is stored on the hard disk. This extra string might be "backtrack". So to decrypt the Truecrypt volume, the password is "monkeybacktrack".
    Hmm... I detect some circular reasoning. The second half of the key that is needed to decrypt the drive resides on the actual hard drive and cannot be obtained in clear text before the drive already is decrypted.

    I think a better approach would be to use Truecrypt to encrypt the entire HDD, and as the password use a strong alphanumeric phrase accompanied by a file that is stored on an USB drive. This is a very secure set-up which woul virtually ensure that as long as the USB drive is not stolen along with the laptop the encrypted data is safe. And even if the USB drive is stolen as well the thief has no way of knowing neither that one of the files on the flash drive is needed or the actual password that the user has to input along with the file.
    Quote Originally Posted by Virchanza View Post
    The computer can have a countdown clock that destroys the "backtrack" password stored on the harddisk. Everytime you connect to the internet, the countdown clock gets refreshed to 1 week. So if the computer were to disappear and never be seen on the internet again, it would still time out after 1 week.
    In my ears this sounds more of a hassle for the user, remember to connect at least once a week no matter what or all your data is lost, than a working security measure. Since the thief would not be able to boot the computer in the first place without decrypting the data on it, he would most wipe the HDD himself in order to be able to use his newly obtained toy. If he on the other hand did manage to do this, he could easily backup all of your sensitive data long before this self destruct function would ever kick in.
    -Monkeys are like nature's humans.

  6. #46
    Very good friend of the forum Virchanza's Avatar
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    Quote Originally Posted by =Tron= View Post
    Hmm... I detect some circular reasoning. The second half of the key that is needed to decrypt the drive resides on the actual hard drive and cannot be obtained in clear text before the drive already is decrypted.
    No, the second part of the password is stored in clear text outside of the Truecrypt archive. Or, you have the option of using the first part of the password to decrypt a file that contains the second part.

    When you want the data to be inaccessible, you simply overwrite the "second part password file". You can do this one of two ways:
    1) As I've described already, using a countdown method whereby if the machine doesn't connect to the internet in 3 consequetive days, it automatically shreds the second part of the password.
    2) You could set the computer up to receive remote instructions to shred the "second part of the password file".

    Just one option of many. To be honest I'd just tell the man I know where his family lives.

    In my ears this sounds more of a hassle for the user, remember to connect at least once a week no matter what or all your data is lost, than a working security measure.
    It wouldn't be lost, just inaccessible until he connects to the internet again and gets the second part of the password again.
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  7. #47
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    Quote Originally Posted by Virchanza View Post
    No, the second part of the password is stored in clear text outside of the Truecrypt archive. Or, you have the option of using the first part of the password to decrypt a file that contains the second part.
    Yes naturally this is how it has to be done, that is what I was trying to point out in my last post. However, any security measure is only as strong as its weakest link which means that the "monkey" part is essentially the only thing protecting your data. If you on the other hand physically separate the second part of the required input, see my example of using a keyfile stored on an USB drive, you have an additional security layer.

    Quote Originally Posted by Virchanza View Post
    When you want the data to be inaccessible, you simply overwrite the "second part password file". You can do this one of two ways:
    1) As I've described already, using a countdown method whereby if the machine doesn't connect to the internet in 3 consequetive days, it automatically shreds the second part of the password.
    2) You could set the computer up to receive remote instructions to shred the "second part of the password file".

    Just one option of many. To be honest I'd just tell the man I know where his family lives.

    It wouldn't be lost, just inaccessible until he connects to the internet again and gets the second part of the password again.
    Once again I feel all of this would be more of a hassle than an actual security measure. Why go through the process of destroying and re-obtaining the second part of the password at all when you can simply separate it from the protected data in the first place. Looking at it in a simplified version you are simply choosing to store the keyfile on a remote location accessible only through an internet connection, instead of having it on an USB drive. This along with the fact that the self destruct mechanism and the retrieval option would only provide a smart thief with clues that this keyfile is important and perhaps lead him to the conclusion that it is part of the encryption mechanism. Having the keyfile stored separately in the first place gets rid of these clues, without actually weakening the system in any way.
    -Monkeys are like nature's humans.

  8. #48
    Very good friend of the forum Virchanza's Avatar
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    Quote Originally Posted by =Tron= View Post
    Looking at it in a simplified version you are simply choosing to store the keyfile on a remote location accessible only through an internet connection, instead of having it on an USB drive. This along with the fact that the self destruct mechanism and the retrieval option would only provide a smart thief with clues that this keyfile is important and perhaps lead him to the conclusion that it is part of the encryption mechanism. Having the keyfile stored separately in the first place gets rid of these clues, without actually weakening the system in any way.
    I just realised I don't think we're on the same page... I was talking about protecting against theft by an employee rather than some junkie running around pulling laptops off people's shoulders. I think you were talking about junkie theft.

    Protecting against junkies is easy, you just encrypt the data, and Mr Junky doesn't have the password. Protecting against employees is harder, which is why I suggest getting the "second part" from the internet (because it's too easy for an employee to rob the USB stick along with the laptop).
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  9. #49
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    Quote Originally Posted by Virchanza View Post
    I just realised I don't think we're on the same page... I was talking about protecting against theft by an employee rather than some junkie running around pulling laptops off people's shoulders. I think you were talking about junkie theft.

    Protecting against junkies is easy, you just encrypt the data, and Mr Junky doesn't have the password. Protecting against employees is harder, which is why I suggest getting the "second part" from the internet (because it's too easy for an employee to rob the USB stick along with the laptop).
    Yes you are correct I was talking about theft in general by a person who does not have authorized access to the computer in the first place and realize that I thereby was getting sidetracked from the actual topic. But as far as protecting the data from employees goes I see no benefit at all in encrypting the data. As the employee naturally will have to have access to the encrypted data as long as he is employed in order to be able to do his work it would be trivial to simply copy the sensitive data if this is what he is after.
    -Monkeys are like nature's humans.

  10. #50
    My life is this forum Barry's Avatar
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    When it comes down to it, there's really no way to protect company data from the company employees. Short of disabling the usb/cdr/firewire/serial/parallel/ir/bluetooth/wifi, they're going to be able to copy the data to some external source. Technically they could just take photo's of the screen. If you knew the employee was getting the boot, you could disable their account making it more difficult to log in, but for those "I quit" situations you're really sol. That's why they make lawyers.
    Of course, if you really wanted to have some fun, go to Wal-Mart late at night and ask the greeter if they could help you find trashbags, roll of carpet, rope, quicklime, clorox and a shovel. See if they give you any strange looks. --Streaker69

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