Cracking
FileVault
Cracking FileVault is a bit of a misnomer. As of this
writing, here is not a known flaw in the 128 bit AES
encryption that is being used. When attempting to open a
FileVault encrypted Home directory, there are two methods
which can be used:
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Brute Force
Brute Force with a dictionary attack
When the Brute Force method is used, this means that every
combination of every letter, number, special character, etc.
is being tried until the correct password is found. If you
choose this method, good luck! This is VERY time consuming.
When a dictionary attack is used, we narrow the scope of the
tries with a crafted list of words. The attack is using the
human flaw of weak passwords OR the potential that the user
left their very strong password “just lying around” thru
careless web browsing and caching or passwords and forms.
Cracking FileVault in Tiger was an "easier" task (NOT EASY),
because of the availability of some well crafted attack
utilities that you can download. I do not have them available
here because I have not received permission to post them.
Simply search
MacUpdate.com or
VersionTracker.com for "filevault"
and you will locate something to try.
To deal with each format Apple might use (DMG, sparseimage,
sparsebundle), utilities have now been developed to
dictionary attack with tremendous speed.
Spartan, our utility, is available for
download. This utility is the slowest
in what it attempts to do, because of the way it will
try to do it. It is a true dictionary attack on the
"sparsebundle" by a mount/fail methodology until we get
to a mount/success. Once mounted, Spartan will mount the
"sparsebundle" to the desktop using a shadowfile,
display the password on the screen and quit.
Much faster utilities such as crowbarDMG and Mac Marshal are
now available which will give you speeds Spartan will never
attain in its current form. See the
Mac Forensic Tools page
for all of the latest offerings.
If you are dealing with evidence, lock your "sparsebundle"
before starting!
As with any good examination, don’t let your evidence get
encrypted in the first place! Before shutting down a powered
on Macintosh, collect as much data as possible! This includes
data from the Keychain. Once such utility,
MacLockPick II from Subrosasoft, will
collect the passwords for you, making the “cracking” a
simple task.