CIS Business Computer Forensics and Incident Response. Lab Protocol 06: Password Cracking with Cain and Abel

Transcription

1 CIS 8630 Business Computer Forensics and Incident Response Lab Protocol 06: Password Cracking with Cain and Abel Purpose: Ensure every student gains first-hand experience with password cracking tools. Students will also develop first-hand knowledge in distinguishing brute-force versus dictionary attacks. Students will also experience the distinction between the security of various password parameters such as password length and character set. Materials required: (all downloadable files) passwordhash.txt, dict.zip, ca_setup.exe Deliverable: This lab protocol with answers. Be sure your name and team name is on the material delivered. 1. If you are using your own Windows machine, Download Cain and Abel from It may be necessary to override your Internet security. Download lastest version for Windows NT/2000/XP onto your desktop. 2. If you are using your VM machine, use windows explorer to open the directory, C:\dayspace\Tools\Password Cracking. 3. Run the installer (casetup.exe). Note that your virus checker s active scanner is likely to issue warnings that a password cracker is being accessed. If possible, dismiss the messages without deleting or blocking the files. Be sure to also install the winpcap packet driver when the CA installer prompts. 4. If you are using your own Windows machine, go to download the medium sized dictionary (dict.zip) onto your desktop. Unzip the contents (DICT.TXT) onto your desktop. 5. If you are using your VM machine, unzip C:\dayspace\Tools\Password Cracking\dict.zip onto your desktop. 6. Prior to running the Cain program on your own machine, it may be necessary to suspend the virus checker s active scanning. 1 of 9

2 7. Run Cain using the desktop icon. ( Ignore message Windows firewall is enabled. Some features will not work correctly if received). 8. Click on the cracker tab (if users are listed, right-click and delete them). 2 of 9

3 9. right click in the blank area and chose add to list 10. Now you can add hashes that you want to crack. For now, choose import hashes from local system. Check Include Password History Hashes 11. Answer the following questions: a. How many user accounts are there on your machine? 3 of 9

4 b. Did you find your user account? c. Which accounts have you never used before? 12. If you are using your own Windows achine, download the file Unzip the file to your desktop. 13. If you are using your VM machine, copy the file C:\dayspace\Tools\Password Cracking\dict.zip onto your desktop 14. This file contains the hashes from another system. 15. In Cain and Abel, right click in main pane and select remove all, to take the current information out. Right click again and select add to list like before. This time, choose import hashes from a text file and browse for the file you just saved. Click next 16. The program should now look like the screen below 4 of 9

5 17. Select all the rows then right click and choose brute force attack and then, NTLM hashes. The other options are for other types of password hashes. 5 of 9

6 18. For now, leave the default settings in the form. Look at the options you have to change the predefined character sets, password lengths, and start point. Click on start and let the program run for about a minute. 19. Answer the following questions a. How many hashes were you able to crack in 1 minute? b. Write down the plain text passwords here (you may have more or less) c. How many characters were in the longest plain text password? d. Are the plain text passwords secure or not? Why? 20. After stopping the cracker, experiment with the optional settings and see how they affect the keyspace. Answer the following questions. a. What is the keyspace for a 6 digit password made up of numbers only? 6 of 9

7 _ b. What is the keyspace for a 6 digit password made up of lower case letters only? _ c. What is the keyspace for a 6 digit password made up of upper and lower letters, numbers, symbols and everything else in the last predefined character set? _ d. What do you recommend systems allow in their passwords? _ e. What do you recommend systems require in their passwords? 21. Pretend you listen when someone logs into a machine and you hear them type 5 characters when they enter their password. Adjust the settings and run the cracker again. 22. Select the largest character set and then adjust the max and min length to equal 5. Click start and write below the estimated time left. Do this again with the max and min equal to 6, 7, 8 and 9. a. What recommendations do these results imply for password policies? Exit the brute force cracker 24. Right click and remove all, then reload the hash file. (right click, add to list, import hashes from text file) 25. Select all the accounts (right click, select all) 26. Right click on the hashes and select the dictionary attack, then NTLM hashes 7 of 9

8 27. The dictionary attack dialog box will open. Right click on the (empty) Dictionary listing at the top of the box, and select Add to list. Open the DICT.TXT file that you earlier extracted to your desktop. 28. Leave the defaults and click start 29. Answer the following questions. a. How does the speed of the dictionary attack compare with the brute force attack? 8 of 9

9 b. What is the longest password found? c. Which of the passwords cracked in the brute force attack were discovered in the discovered in the dictionary attack and vice-versa Brute Force Attack Passwords Dictionary Attack Passwords d. What are the advantages and disadvantages of dictionary attacks? e. What recommendations do these results imply for password policies? 9 of 9