“It’s all too common that Web (and other) applications use MD5, SHA1, or SHA-256 to hash user passwords, and more enlightened developers even salt the password. And over the years I’ve seen heated discussions on just how salt values should be generated and on how long they should be. Unfortunately in most cases people overlook the fact that MD and SHA hash families are designed for computational speed, and the quality of your salt values doesn’t really matter when an attacker has gained full control, as happened with rootkit.com. When an attacker has root access, they will get your passwords, salt, and the code that you use to verify the passwords.”

So, I pulled several 14 character complex passwords hashes from a compromised Windows XP SP3 test machine, to see how they would stand up to Objectif’s free online XP hash cracker.

The results were stunning.

Let’s start out with an easy one. Here is the Administrator password hash from the machine:

aad3b435b51404eeaad3b435b51404ee:31d6cfe0d16ae931b73c59 d7e0c089c0

And putting this into Objectif’s tool we get this response:

Password: Empty password…
Time: 2 seconds

Administrator didn’t set a password, that’s not good…

Okay, that wasn’t 14 characters, let’s try a hard one.

How about this one:

Hash: 17817c9fbf9d272af44dfa1cb95cae33:6bcec2ba2597f089189735 afeaa300d4

And the response:

Password: 72@Fee4S@mura!
Time: 5 Seconds

Wow! that took only 5 seconds and that is a decent password.

Let’s try a few more:

Hash: ac93c8016d14e75a2e9b76bb9e8c2bb6:8516cd0838d1a4dfd1ac3e 8eb9811350
Password: (689!!!”QTHp
Time: 8 Seconds

Hash: d4b3b6605abec1a16a794128df6bc4da:14981697efb5db5267236c 5fdbd74af6
Password: *mZ?9%^jS743:!
Time: 5 Seconds (Try typing that in every day!)

And Finally:

Hash: 747747dc6e245f78d18aebeb7cabe1d6:43c6cc2170b7a4ef851a62 2ff15c6055
Password: T&p/E$v-O6,1@}
Time: Okay, this one really pushed it to the limits, it took a whole 11 seconds to crack!

Very impressive, it took only five to eleven seconds in this test to crack 14 character complex passwords.

“After almost three years online, the admin of Free Rainbow Tables has decided to call it a day, citing a lack of time to keep it running. (I’m sure that you all know a rainbow table is essentially a giant list of precomputed hashes.) This is a shame, as the site is a useful resource for those occasions when you really need an existing password exposed, rather than simply changing it. I’m a Windows admin, and this site has come in very handy in the past. The currently computed tables weigh in at well over half a terabyte, are available as torrents from the site, or from a couple of mirrors (and alternatives are available). When the site was active, it featured a downloadable BOINC client to put your idle cycles to work computing ever-greater tables, and a space-saving format for storing the tables. The admin is willing to hand over source code if you wish to take over, though I suspect hosting is not included!”

…

[T]he current Vista release does include support for the LM hash, although it is disabled by default.

…

Because LM hash does not include salt, a time-memory trade-off cryptanalysis attack, such as rainbow tables, is also feasible. In 2003, Ophcrack, an implementation of the rainbow table technique, was published. It specifically targets the weaknesses of LM encryption, and includes pre-computed data sufficient to crack virtually all alphanumeric LM hashes in a few seconds. Many cracking tools, e.g. RainbowCrack, L0phtCrack and Cain, now incorporate similar attacks and make cracking of LM hashes trivial.

…

Rainbow tables are easy to beat. For each password, generate a random number (a nonce). Hash the password with the nonce, and store both the hash and the nonce. The server has enough information to verify passwords (the nonce is stored in the clear). But even with a small random value, say, 16 bits, rainbow tables are infeasible: there are now 65,536 “variants” of each hash, and instead of 300 billion rainbow table entries, you need quadrillions. The nonce in this scheme is called a “salt”.