Physically securing FreeBSD workstations & /boot/boot2

Tim Judd tajudd at gmail.com
Thu Aug 6 19:35:56 UTC 2009


On 8/6/09, Nerius Landys <nlandys at gmail.com> wrote:
> Hi.  I am attempting to secure some workstations in such a way that a
> user would not be able gain full control of the computer (only user
> access). However, they are able to see and touch the physical
> workstation.  Things I'm trying to avoid, to list a couple of
> examples:
>
> 1. Go to BIOS settings and configure it to boot from CD first, then
> stick in a CD.  To prevent this I've put BIOS to only boot from hard
> drive and I've password-locked the BIOS.


You can't beat physical security.  If you have access to the hardware,
you can TAKE the box, saw it open, unmount the hard drive, slave it
into another system, mount it as a data drive and steal the info.
geli encryping the drive can secure the data on the disk, but they
have your disk.  it's as good as stolen data, even if they are unable
to decrypt it.


After sawing open the case, move the jumper to reset CMOS data, power
up, change boot order, and boot off CD.


After BIOS is back to normal, stick in a USB drive, boot off the HDD,
which is self-decrypting the geli encryption, copy the data off, and
scrub the HDD and install Windows on it.  The hacker's OS  (Just
Kidding, all.  Little humor is all I'm doing).



> 2. Go to loader menu and load (boot kernel) with some custom
> parameters or something.  I've secured the loader menu by
> password-protecting it (/boot/loader.conf has password) and
> /boot/loader.conf is not world-readable.

If you can do the above, even booting from alternate medium, no other
means of security will apply.

> And I'm sure there are other things, I just forgot them.
>
> So my question is: Is this [securing of the workstation] worthwhile,
> or should I just forget about this kind of security?  I want to make
> it so that the only way to gain full control of the computer is by
> physically opening up the box.
>
> I noticed that boot2 brings up a menu like this one when I press space
> during the initial boot blocks:
>
>>> FreeBSD/i386 BOOT
> Default: 0:ad(0,a)/boot/loader
> boot:
>
> I guess it would be possible to stick in a floppy disk or something
> and boot from there?  So my question is, is this a threat to my plan,
> and if so, how can I disable this prompt?



Only security in these days is to physically secure the box and leave
it off the network.  Flaws and security problems will always allow
unauthorized access.  But a computer that's not on the network is of
no use.  So it's a loose-loose situation.


Best effort is to know your people, and either trust them, or fire them.


--TJ


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