| 1 | <?xml version='1.0' encoding='UTF-8'?>
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| 2 | <!DOCTYPE topic PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
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| 3 | <topic xml:lang="en-us" id="diskencryption-limitations">
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| 4 | <title>Limitations of Disk Encryption</title>
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| 5 |
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| 6 | <body>
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| 7 | <p>There are some limitations the user needs to be aware of when using this feature: </p>
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| 8 | <ul>
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| 9 | <li>
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| 10 | <p>This feature is part of the <ph conkeyref="vbox-conkeyref-phrases/vbox-ext"/>, which needs to be installed.
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| 11 | Otherwise disk encryption is unavailable. </p>
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| 12 | </li>
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| 13 | <li>
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| 14 | <p>Since encryption works only on the stored user data, it is currently not possible to check for metadata
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| 15 | integrity of the disk image. Attackers might destroy data by removing or changing blocks of data in the image
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| 16 | or change metadata items such as the disk size. </p>
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| 17 | </li>
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| 18 | <li>
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| 19 | <p>Exporting appliances which contain encrypted disk images is not possible because the OVF specification does
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| 20 | not support this. All images are therefore decrypted during export. </p>
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| 21 | </li>
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| 22 | <li>
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| 23 | <p>The DEK is kept in memory while the VM is running to be able to decrypt data read and encrypt data written by
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| 24 | the guest. While this should be obvious the user needs to be aware of this because an attacker might be able
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| 25 | to extract the key on a compromised host and decrypt the data. </p>
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| 26 | </li>
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| 27 | <li>
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| 28 | <p>When encrypting or decrypting the images, the password is passed in clear text using the <ph
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| 29 | conkeyref="vbox-conkeyref-phrases/product-name"/> API. This needs to be kept in mind, especially when using
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| 30 | third party API clients which make use of the webservice where the password might be transmitted over the
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| 31 | network. The use of HTTPS is mandatory in such a case. </p>
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| 32 | </li>
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| 33 | <li>
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| 34 | <p>Encrypting images with differencing images is only possible if there are no snapshots or a linear chain of
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| 35 | snapshots. This limitation may be addressed in a future <ph conkeyref="vbox-conkeyref-phrases/product-name"/>
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| 36 | version. </p>
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| 37 | </li>
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| 38 | <li>
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| 39 | <p>The disk encryption feature can protect the content of the disks configured for a VM only. It does not cover
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| 40 | any other data related to a VM, including saved state or the configuration file itself. </p>
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| 41 | </li>
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| 42 | </ul>
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| 43 | </body>
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| 44 |
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| 45 | </topic>
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