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    SubjectRe: NFS4 authentification / fsuid


    On Wed, 19 Sep 2007, Kyle Moffett wrote:
    >
    > On Sep 18, 2007, at 19:44:59, Satyam Sharma wrote:
    > >
    > > The whole *point* here is to secure against physical access -- then how can
    ^^^^^^^^^^^^^^^
    > > you assume "barring disassembling the system"? If you're not considering
    > > attacks such as those, then how _are_ you solving the physical access
    > > problem in the first place? :-)
    >
    > [snip lots of totally irrelevant stuff]

    ???

    What is your point, really?

    Let me repeat the situation:

    I own a computer (maybe portable one, such as a laptop) that I want to
    protect from attackers with physical access to my system. You're proposing
    a scheme that claims to secure it (against attackers with physical access)
    but assumes: "barring disassembling the system".

    Dude, looks like you're selling snake oil here.


    > > > Under this setup, tinkering with my BIOS does virtually nothing; the only
    > > > avenues of attack are strictly of the "Install a hardware keylogger"
    > > > variety.
    > >
    > > Doesn't flashing/replacing your BIOS firmware/chip count as tinkering? Then
    > > I don't really need a "hardware keylogger", do I ...
    >
    > Ok, so you are saying your plan of attack on this system would be:
    > 1) Steal the laptop such that I don't notice it has been stolen
    > 2) Open it up
    > 3) Replace the very-vendor-specific BIOS chip with a reflashed one with
    > sufficient storage to do all the things the old BIOS could *AND* have enough
    > storage for an entire replacement kernel binary with a built-in keylogger, as
    > well as some storage for the logged password
    > 4) Return the laptop, again such that I don't notice it has been missing
    > 5) Wait for me to boot and type my password
    > 6) Somehow recover the laptop *yet* *again* to get the password back off of
    > it and decrypt the disk

    Precisely. Do you think the above attack is "fantastical"?

    Wow, you're amazingly naive ... good luck ;-)

    [ See, if it's only your kid sister that you want to "protect" your
    36GB worth of porn from, then you might as well use Windoze and one of
    those cute little "folder-locking" tool that we wrote back in 5th grade.

    However, if "hapless North Korean spy in Washington" describes you more
    accurately, then you better be ready for all sorts of attacks -- from
    exploding cigars [1], to poisoned ballpoint pens [2] :-)

    In short, you have no clue what you're talking about, and thankfully
    I'm not using any security software you had any part in designing :-) ]


    > Yes it "can be done", but so can dumping the firmware for an iPod out through
    > the built-in piezo clicker[1]. USE SOME COMMON SENSE HERE PEOPLE!!! The only
    > "unbreakable" computer is one always disconnected and off under armed guard in
    > a bank vault, and even then it's only as secure as the bank in which it is
    > stored (which get broken into on occasion).

    Thanks for repeatedly making *my* point :-)

    _You_ are the one who claimed protecting systems from attackers with
    physical access to be a "fairly simple" problem ... and here you're
    mentioning how *difficult* it is ...


    > I am assuming that if the laptop has sufficiently important data on it to
    > warrant the above steps then I am also clueful enough to:
    > (A) Not carry the laptop around unsecured areas,

    You might carry it home, might you not? What if your lover/girlfriend/wife
    is one of them? [3]


    > (B) Keep a close enough eye on it and be aware that it's gone by the time
    > they get to step 2, OR

    Hmm, you'd need to be a mutant to keep "close enough eyes" on your stuff
    while you're sleeping ... or drugged (?)


    > (C) Pay somebody to build me a better physical chassis for my laptop

    ROTFL ... these "workarounds" above are even more hilarious than your
    earlier "fairly simple" claim.


    > We are talking about *STANDARD* laptop systems with reasonably alert users.
    > If the user doesn't know how to properly protect the stuff on the laptop then
    > they probably don't know how to properly protect the other copy in their
    > heads, either.

    Dude, if the data in there is really that important, then better not
    store it on a computer / disk at all :-)


    > Besides, if some government wanted the data on your laptop
    > that bad they'd just pick you up in the middle of the night and torture your
    > password out of you.

    Surprisingly, you have (somewhat of) a point (!)


    > On Sep 18, 2007, at 19:48:16, Satyam Sharma wrote:
    > > On Fri, 7 Sep 2007, Kyle Moffett wrote:
    > > > So you can't draw any relationships between "Protect the end-user" with
    > > > "Protect the device FROM the end-user", the former can be done very
    > > > reliably to whatever level of risk-reduction you need and the latter can't
    > > > practically be done at all.
    > >
    > > Well, you're the one who called solving the physical access problem "easy"
    > > here ... :-)
    >
    > If your system equates end-user with attacker
    ^^

    "If"? Was there ever any doubt?

    Heh, did you even read the thread you just replied to?

    We're talking of consoles / hardware sold by commercial companies to
    users here, where they want explicitly want to prevent the users from
    being able to hack it. So yes, end user == attacker.

    > then you are *screwed* regardless!

    Ah, finally you make my point again for me :-)


    Thanks for the laughs,

    Satyam


    [1] }
    [2] } All real "attacks". History pop quiz: on whom? ;-)
    [3] }
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