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Francesco (frodsan) [email protected]

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Web Security 101

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Passwords

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How not to!

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#1 Just store it!

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#2 Encryption

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Encryption is reversible

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DES 3DES AES

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#3 Hashing

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Hashing is irreversible

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hash(“mypassword”) “34819d7beeabb9260a5c854bc85b3e44”

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hash(?) “e10adc3949ba59abbe56e057f20f883e”

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Hashing is deterministic

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hash(“mypassword”) “34819d7beeabb9260a5c854bc85b3e44” ! hash(“mypassword”) “34819d7beeabb9260a5c854bc85b3e44”

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hash(“mypassword”) “34819d7beeabb9260a5c854bc85b3e44” ! hash(“mupassword”) “b11d7ccaee763e5840f9d906e0bf2edf”

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Hashing is deterministic

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hash(“mypassword”) “34819d7beeabb9260a5c854bc85b3e44” ! hash(“mypassword”) “34819d7beeabb9260a5c854bc85b3e44”

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thelonelyones.heroku.com/passwords.csv
 thelonelyones.heroku.com/login Exercise

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Lookup tables

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Adobe Security Breach (2013) 38 million active users
 passwords, credit card information

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http://xkcd.com/1286/

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MD5
 SHA1 SHA2

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✓ Hashing + Salting

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hash(“mypassword”) “34819d7beeabb9260a5c854bc85b3e44”

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hash(“mypassword”, salt)

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hash(“mypassword”, e8ed4834c7dd0…) “21b9558e8920bddb04949c068181c…”

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hash(“mypassword”, e8ed4834c7dd0…) “21b9558e8920bddb04949c068181c…
 
 hash(“mypassword”, 1bc1fa3bc1d5d85…)
 e92a46f76d413ce73ab5796756bc92…

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1976 - crypt(3)

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GPU
 FPGA

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PBKDF2
 Bcrypt Scrypt

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PBKDF2 (armor, pbkdf2)
 Bcrypt (bcrypt) Scrypt (scrypt)

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How to do it

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ʕ•ᴥ•ʔ ! • Don’t do it (leave it to GitHub, Google, etc.) • If you must do it, use pbkdf2 or bcrypt or scrypt. • Keep password length between 8 and 50. • Nothing can save you easy to guess passwords.

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Cross Site Scripting - XSS

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1993

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!

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Web Security 101

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?

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Escaping

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Angle brackets: > <

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1995

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JavaScript

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!

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var message = "Web Security 101"; ! alert(message);

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var message = "<b>Web Security 101</b>"; ! document.write(message);

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JavaScript == DANGER

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“Samy is my hero” (2005) • XSS attack propagated by Myspace profiles. ! • Over one million affected users within the first 20 hours. ! • 3 years without computer.

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How to do it

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Escaping

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UNSAFE = /[&"'><\/]/ ! HTML_ESCAPE = { "&" => "&", ">" => ">", "<" => "<", '"' => """, "'" => "'", "/" => "/" } ! string.gsub(UNSAFE, HTML_ESCAPE)

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UNSAFE = /[&"'><\/]/ ! HTML_ESCAPE = { "&" => "&", ">" => ">", "<" => "<", '"' => """, "'" => "'", "/" => "/" } ! string.gsub(UNSAFE, HTML_ESCAPE)

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github.com/frodsan/hache

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References

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• OWASP Top 10:
 https://www.owasp.org
 
 • Adobe 10GB database passwords leak:
 http://bit.ly/188ctZL
 • MySpace XSS vulnerability:
 http://bit.ly/1urMIbG
 • Tweetdeck XSS vulnerability:
 http://bit.ly/1urMGAy


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thanks ʕ•ᴥ•ʔ