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On Sun, Jun 17, 2012 at 4:30 PM, Florian Philipp <lists@×××××××××××.net> wrote: |
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> Am 17.06.2012 20:56, schrieb Sascha Cunz: |
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>> I was under the impression that it should at least help in that scenario. |
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>> OTOH, if it takes a compromised system or physical access to the machine in |
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>> order to manipulate the boot sequence, then I no longer understand what the |
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>> boot sequence in such a system must be protected against (Assuming that the |
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>> primary reason for boot sequence manipulation is to later on compromise the |
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>> system). |
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>> |
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> |
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> Well, it does help, especially when you also prevent changing UEFI |
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> settings with a password. However, there are so many variables and |
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> possibilities when talking about attacks on physically accessible |
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> systems, that you're usually screwed anyway. |
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|
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I'd view secure boot as complementary to TPM. |
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|
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TPM keeps somebody with physical access from being able to access |
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important information on your computer, since that data would be |
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encrypted and the keys would not be surrendered by the TPM module |
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without a proper chain of trust. |
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|
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TPM is potentially more secure, although it has a fatal flaw in that |
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if the OS is compromised then the keys can be obtained (since the OS |
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needs the keys to access the disk) and a trojan can be installed on |
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the bootloader. That trojan is difficult to remove or even detect |
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even if you update your virus scanners/etc. Secure boot keeps trojans |
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out of the early boot chain, making them easier to clean up once your |
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system is further updated. |
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|
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Secure boot is also somewhat easier to implement, and a bit more |
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recoverable if things go wrong. If you're using TPM and trusted grub |
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and all that, then if you mess up your trusted boot chain then you may |
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never get back the contents of your drive, unless you kept a copy of |
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various keys elsewhere. |
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|
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Rich |