Hack Windows XP Password dengan Ophcrack

Intro

Sebelumnya saya pernah membuat tutorial mengenai Hack Windows XP (SP2) Passwords menggunakan pwdump6. Namun, cara tersebut mengharuskan user dengan status admin agar dapat ‘dump’ file HASH dari Windows. Sekarang saya akan menyampaikan cara lain untuk ‘cracking’ password Windows XP (semua versi) dengan menggunakan Ophcrack.

Ophcrack is a Windows password cracker based on rainbow tables. It is a very efficient implementation of rainbow tables done by the inventors of the method. It comes with a GTK+ Graphical User Interface and runs on Windows, Mac OS X (Intel CPU) as well as on Linux.

Hebatnya lagi, Ophcrack tersedia dalam bentuk LiveCD, sehingga tidak diperlukan proses instalasi dan tidak perlu password admin, hanya butuh akses agar komputer dapat booting dari CD (biasanya urutan booting default BIOS komputer saat ini dimulai dari CD/DVD ROM, so don’t worry) . Ophcrack LiveCD merupakan Linux yang berbasis SLAX (turunan dari Slackware) dan sudah terdapat Ophcrack dan Rainbow Table untuk cracking password alpanumerik.

Intinya hampir sama dengan cara kerja pwdump6, namun karena Ophcrack menggunakan linux LiveCD sehingga dapat langsung mount file sistem Windows tanpa perlu login ke Windows serta membaca file Hash (windows\system32\config) dan melakukan dump ke file text biasa yang kemudian dapat langsung di crack. Dan hebatnya, tidak perlu Tools seperti JTR lagi, karena crack dilakukan dengan Ophcrack menggunakan Rainbow Table dan memberikan hasil yang sangat cepat.
Ok.. langsung aja kita praktek, tapi sebelumnya pasang disclaimer dulu ah… biar bisa ‘lepas’ tanggung jawab kalau tutorial ini disalahgunakan oleh pihak lain

Disclaimer:
This document was written in the interest of education and care of awareness for unaware people. The author cannot be held responsible for how the topics discussed in this document are applied. 

Lets Begin
Pertama kali anda harus mendownload file ISO Ophcrack LiveCD dari sini. Lalu burn ke dalam CD. Dan selanjutnya boot Komputer ‘target’ dari Ophcrack LiveCD, maka akan tampak seperti ini :

Tekan Enter dan biarkan proses Booting berlangsung. Ophcrack akan otomatis masuk ke windows manager menggunakan fluxbox dan langsung menjalankan Ophcrack. Proses pertama adalah mendapatkan file HASH dari partisi yang berisi file Windows kemudian di dump ke file /tmp/ophcrack.tmp

Kemudian tunggu beberapa saat untuk melakukan cracking.

Saya melakukan pengujian menggunakan spesifikasi sebagai berikut : Prosessor AMD +2000 1.6 Ghz, Memori 256 Mb dan dijalankan menggunakan VM-Ware.

Lalu saya menggunakan password yang sangat sederhana, yaitu ‘password123′ dan ‘password’. Hasilnya, Ophcrack mampu menebak kedua password dengan tepat dan hanya membutuhkan waktu 1 Menit!! 

Lalu saya coba untuk mengkombinasikan huruf, angka dan simbol dengan memberikan password : ‘p4ssw0rd’ dan ‘p4ssw0rd~!@#’. Hasilnya, Ophcrack mampu menebak ‘p4ssw0rd’ dengan waktu 8 menit dan tidak dapat menemukan ‘p4ssw0rd~!@#’.


Selain menggunakan CD, dengan sedikit modifikasi, Ophcrack juga dapat dijalankan melalui USB Flashdisk. Caranya dengan menginstall SLAX ke dalam USB Flashdisk dan menambahkan modul ophcrack di SLAX serta menyalin Rainbow Tables ke dalam USB, maka Ophcrack LiveUSB sudah dapat dijalankan
Selain itu, untuk mempersingkat waktu, kita dapat mengambil file HASH terlebih dahulu yang terletak di /tmp/ophcrack.tmp kemudian baru di crack di tempat lain tanpa perlu menunggu lagi di komputer target.

Saran
Ibarat pisau bermata dua, Ophcrack dapat menjadi sangat berguna ketika ada seseorang yang lupa password Windows dan ingin me-recovery password dengan cepat dan mudah. Namun disisi lain, Ophcrack dapat juga menjadi ‘senjata’ ampuh bagi cracker untuk menjebol Windows dengan cara yang sangat mudah dan cepat. Bahkan kabarnya Ophcrack ini merupakan tools yang paling cepat untuk crack password Windows. Untuk itu ada beberapa hal yang dapat mengurangi resiko agar password komputer kita tidak ‘dibobol’ dengan mudah.

1. Setting password BIOS komputer dan atur urutan boot agar tidak melakukan booting pertama kali dari CD atau USB.

2. Gunakan password yang terdiri dari huruf+angka+simbol agar tidak mudah di crack.
Oph… Crack!!

This is a guide for cracking passwords in Windows under XP, 2000, 98, and 95, all of which use roughly the same architecture. As you know, passwords are stored in windows in a weak hash form, the first kind of which is called the LM (Lan Manager) Hash. Passwords longer than 7 characters are broken up into 7-character chunks, made uppercase, and then hashed with DES. This means there are only about 2³⁷ 8-bit hashes instead of 2⁸³ 16-bit hashes; a good thing for an attacker looking to break a password.

The tool we’ll be using is called Ophcrack, an open-source password cracker. The technology it uses to break Windows passwords is called “rainbow tables” and was described by Philippe Oechslin in Making a Faster Cryptanalytic Time-Memory Trade-Off. A rough way to describe this technique is to say that tables of possible hashes are precomputed so that you can iteratively compare the windows hashes to precomputed bits and piece together the hash and its value more quickly than brute-force guessing.

Please note that federal law prohibits the possession of unauthorized access codes to computer systems. If you want to try cracking passwords, please obtain hashes from your own machine, or use the example hashes I provide here.

1) Setting up shop
The first thing you need is the software and rainbow table sets. You can download Ophcrack 2.2 from Sourceforge, and then browse to LASEC to download the SSTIC04-5k rainbow table. You’ll need a significant amount of memory to load this rainbow table. If you have less than 1 GB of RAM, try the smaller table.
The installation of Ophcrack 2.2 should go smoothly. Make sure you choose to download the tables seperately:

You’ll notice a lot of GTK* files being installed–that’s nothing to worry about. GTK is the Graphical Tool Kit, a way for linux programs to create graphical interfaces.

2) Dude, where’s my hash?
Now that you’ve got Ophcrack and rainbow tables installed, you’ll need hashes. There are three places to find them on Windows XP:

• In the folder C:\windows\system32\config. This folder is locked to all accounts (including an Administrator account) while running, except the special System account.
• In a SAM file from C:\windows\repair if rdisk has ever run
• In the registry, under HKEY_LOCAL_MACHINESAM, which is locked to all accounts

This doesn’t look good for retreiving the windows hashes! Well, to work around the built-in windows protections, we can recover hashes by the following techniques:

• Boot to linux and copy the file directly from C:\windows\system32\config. This is probably too troublesome for most users, but with a liveCD it’s trivial.
• Run pwdump2, including in Ophcrack, to trick out the registry values. If you didn’t change any settings, it should be installed in C:\Program Files\ophcrack\win32_tools. Here’s an example session from the command line (start, run, type “cmd” and hit enter):

C:\Documents and Settings\Elliott Back>cd “C:\Program Files\ophcrack\win32_tools”
C:\Program Files\ophcrack\win32_tools>pwdump2
Administrator:499:aabbcc:3311dd:::
Elliott Back:234:aabbcc:3311dd:::
C:\Program Files\ophcrack\win32_tools>
Naturally, I’ve censored the hashes and the number of users. If you’d like some hashes to play with, here are hashes for users with passwords varying from length from 1 to 7 characters long: test-hashes.txt.

3) Let’s get cracking!
Hashes in hand, start up Ophcrack:

Then click “load, PWDump file,” and select either the hashes you got from pwdump2, my sample hash file, or some other source of SAM hashes:

The last thing we need to do is load our rainbow tables. Click “Tables” and select the location and type of rainbow hash table you’re using, in our case the 5k tables:

Now you can click the big “Launch” button and wait. It will first load the tables (0-3 in my case) into memory, a process that takes several minutes. When this is complete, it will begin trying passwords:

The final screen gives a breakdown on how long it takes to actually find these passwords–some of which are quite hard:

All in all, it took 178 seconds on average to crack a windows password–only 3 minutes per hash! In the process it performed 89,030,630 hash-redux calculations and 199,548 fseek operations. It also couldn’t find the password for one of the hashes, which is to be expected. Rainbow tables are non-deterministic and won’t always work. Still, our success rate of 6/7 or 86% is high.

Conclusion
Now you know how to crack windows passwords. When is this a good idea?

1. When you buy a computer on Ebay and the owner forgets to give you an Admin account
2. When you forget your password
3. When a friend forgets their password
4. When the security of the country is in danger

When is this a bad idea?

1. When you buy a computer from government surpluss and want to find its secrets
2. When you want to hack up your friends
3. When your little sister’s account is too tempting
4. When you go visit your girlfriend’s dorm room

Another problem with releasing a tool like Ophcrack is that it becomes usable by anyone. In fact, this guide or tutorial to cracking windows passwords even makes it easier. Pretty much anyone can crack any windows password now, which could be a problem if used the wrong way. However, windows passwords are by nature insecure; there are dozens of other tools to crack windows passwords. Ophcrack is just the fastest.