ZeroNights2013 testing of password policy
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Anton Dedov tested several popular password meters to evaluate their security effectiveness and user-friendliness. He found that passwdqc and zxcvbn were most balanced, blocking common attacks while still accepting passwords users find intuitive. All meters protected against online attacks, and likely offline attacks with slow hashes and unique salts. However, most denied more passwords than necessary, including strong, uncommon passwords. Larger dictionaries and real user studies could provide more insights. Special thanks were given to security experts who advance password protection.
![Motivation
• It is hard for application developers to choose
between existing password meters reasonably.
• Worse, some implement their own [or
customize existing] without understanding of
security and psychological implications.
• Need some framework/criteria that would
help reasonable choice.
3](https://image.slidesharecdn.com/zn2013testingofpasswordpolicyabridged-131108075726-phpapp02/85/ZeroNights2013-testing-of-password-policy-3-320.jpg)
ZeroNights2013 testing of password policy
- 1. Testing of Password Policy Anton Dedov ZeroNights 2013
- 2. Who Am I • Software Developer and Security Engineer @ Parallels Automation • Open source developer • Mail: adedov@gmail.com • Twitter: @brutemorse
- 3. Motivation • It is hard for application developers to choose between existing password meters reasonably. • Worse, some implement their own [or customize existing] without understanding of security and psychological implications. • Need some framework/criteria that would help reasonable choice. 3
- 5. Untargeted Online Attacks User base Common passwords 100 K • 1 guess per user / day • 2 days to find first password • 100 days to find 50 passwords 10 K 100 K 2.5 K 5K • 1 guess per user / day • 10 days to find first password • 1.5yr to find 50 passwords
- 6. Targeted Online Attacks • • • • • 10 failed attempts 1 hour block 240 attempts per user / day 7200 attempts per user / month 86400 attempts per user / year More IP-s scale linearly
- 7. Offline Attacks • Huge dictionaries • Specialized hardware and clusters • No time/complexity limitations except – Enforced password quality – Hash speed – Salt uniqueness 7
- 10. Method • • • • Apply meters to password bases Dictionary attacks with JtR Rule-based attacks with JtR Collect essential parameters
- 11. Apply Meters • Requirement: meter should provide unambiguous signal about if password is accepted or not. • Passwdqc tells straight “OK” or “Bad”. • Others return score. Minimal accepted score documented. 11
- 12. Password Bases • • • • • Real customers RockYou all CMIYC-2010 not cracked Random passphrases Random 10-char passwords Red for attacks; blue for psychological acceptance. 12
- 13. Dictionaries Dictionary Tiny English RockYou top Common-passwords English Tiny English crossed / 8 chars Size, words 817 1438 3546 54316 72100 13
- 14. Rules Rule JtR defaults JtR jumbo m3g9tr0n-2048512 m3g9tr0n-2048517 Factor ~ 40 ~ 5500 = 3510 ~ 860 14
- 15. Cracking Sessions None JtR default Tiny 817 words 41K words JtR jumbo 4M words m3g9tr0n2048512 2.8M words m3g9tr0n2048517 707K words 15
- 16. Cracking Sessions • 25 attacks per password base per meter • Min dictionary size 817 • Max dictionary size 396M RockYou dictionary was not used against RockYou password base. 16
- 17. Parameters • M – passwords approved by meter • D – attack dictionary size • C – # of guessed passwords during attack • Attack effectiveness • Attack economy C M C D 17
- 18. Online Attacks Effectiveness For dictionaries < 100K Max guess rate 0.007% 18
- 22. Guesses Totals Meter plesk passwdqc zxcvbn complexify libpwquality RockYou Customer 1 Customer 2 0.08% 0.18% 0.54% 0.54% 1.16% 0.28% 0.23% 0.26% 1.06% 0.50% 0.28% 0.12% 0.06% 0.40% 0.45%
- 24. Psy. Acceptance: User Passwords Meter plesk passwdqc zxcvbn complexify libpwquality RockYou Customer 1 Customer 2 0.21% 1.60% 5.43% 2.03% 4.32% 3.45% 14.90% 16.29% 7.05% 11.88% 5.53% 40.62% 43.16% 27.18% 34.27%
- 25. Psy. Acceptance: User Passwords 70.00% 60.00% 50.00% 40.00% customer2 customer1 30.00% rockyou-all 20.00% 10.00% 0.00% passwdqc plesk zxcvbn complexify pwquality 25
- 26. Psy. Acceptance: Hard Passwords Meter plesk passwdqc zxcvbn complexify libpwquality CMYIC-2010 Pass-Phrases 24% 59% 42% 3% 10% 0% 99.98% 99.76% 99.94% 99.82% Random 10 chars 42% 100% 99.99% 0% 81% 26
- 27. Psy. Acceptance: Hard Passwords 100.00% 90.00% 80.00% 70.00% 60.00% CMIYC2010-uncracked 50.00% phrases-rand39 40.00% random10 30.00% 20.00% 10.00% 0.00% passwdqc plesk zxcvbn complexify pwquality 27
- 29. Conclusions • • • • Test your security tools for security Avoid write your own security tools All tested meters protect from online attacks Also seem protect from offline attacks (for slow hashes and unique salts) • But most tend to deny more passwords than it is necessary, including known to be hard ones • Passwdqc and zxcvbn look best
- 30. Where to go? • Bigger dictionaries and brute force • Testing on real people to – Learn evolution of “common passwords” lists – Test psychological acceptance empirically • More meters? 30
- 31. Special thanks Alexander Peslyak Solar Designer 31
- 32. Bonus: time to process RockYou… (MBP 2011) 3:15 zxcvbn pwquality plesk passwdqc complexify 5:48 0:13 0:26 0:16 0:00 1:12 2:24 3:36 Hours 4:48 6:00 7:12