that was then, this is now: a security evaluation of password … · evaluation of password...
TRANSCRIPT
That Was Then, This Is Now: A Security Evaluation of Password
Generation, Storage, and Autofill in Browser-Based Password Managers
Scott RuotiSean Oesch
Motivation
• Passwords are still the dominant form of authentication, but they have serious shortcomings
• Password managers can help users generate strong, unique passwords, but how secure are the password managers themselves?
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Generation
Storage
Autofill
The password lifecycle
Standalone App Password Managers
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Extension Based Password Managers
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Browser Password Managers
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Autofill, Generation, and StorageRecommended behaviors and security concerns
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Autofill
• Require user interaction before filling credential• Prevents automatic credential scraping
• Increases the probably the user can detect attacks
• Refuse to fill forms in iframes• Significantly reduces the attack surface
• Refuse to submit password over insecure connections
• Avoid filling suspicious forms
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Firefox Credential Scraping Demo
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Generation
• Generate passwords that are resilient to online/offline attack• Resist ~106 guesses for online resilience
• Resist ~1014 guesses for offline resilience
• Preserve safe settings− Default: length 20, all character sets
− Modify: length 8, letters and digits
− Should restore default secure settings after modification
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Random But Weak Passwords
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• Most randomly generated passwords are resilient to online and offline attacks
• A small portion will be trivially guessed by brute force attacks• LastPass - 17M users, generate 1
password each, 730 weak passwords
• Probability is negligible for sufficiently long passwords• 10 characters for online resistance• 18 characters for offline resistance
Storage
• Master password should be strong• Single point of failure
• Strong Key Derivation Function (KDF) should be used
• Metadata should be encrypted
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Wrap-upRecommendations and future work
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Conclusion• Recommendations• Require user interaction for autofill• Filter weak passwords during generation• Better master password policies for storage
• Future Work• Browser-supported password managers− Safer autofill
• Research-derived character sets• HTML-supported password generation• Mobile password managers
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