Your Passwords

are being sold

why?

• Direct access to the affected account
• May compromise other accounts (email, bank, etc)
• Add password cracking corpus

how?

• Server Hacked (Gawker 2010)
• Vulnerability in Site (RockYou 2009)
• Database Backup Stolen (Bitly 2014)

let's look at how

passwords are being stored...

Plaintext

but why would you ever?

• Really easy to implement (lazy)
• Allows for easy password recovery
• Straightforward, simple comparison

NEVER use plaintext

but who is that stupid?

• 30% of websites store passwords in plaintext
• MySpace, RockYou, Hotmail
• If they know your password, they're storing plaintext

Reversible Encryption

now what?

Hashing

Hashing

Specifically, a "one-way cryptographic hash"

password123

8640bd46

password123

8640bd46

but what about password?

 how do it know?

We don't know the password, but we can still authenticate the user with her password

win?

Cracking Passwords

brute force

• Hash every password combination
• If any digest matches, you know the input password

0000000

0000001

0000002

0000003

0000004

0000005

0000006

00000A5

00000A6

00000A7

00000A8

00000A9

00000B0

00000Ba

0000ga0

0000gaa

0000gab

0000gac

0000gad

0000gae

0000gaf

0001dFk

0001dFl

0001dFm

0001dFn

0001dFo

0001dFp

0001dFq

000h4xu

000h4xv

000h4xw

000h4xx

000h4xy

000h4xz

000h4xA

• 180 billion MD5 hashes per sec
• Alphanumeric: 
  • 26 lowercase
  • 26 uppercase
  • 10 numbers
• 8 character password:
  • (26 + 26 + 10) ^ 8 = 280 trillion
• 280 trillion / 180 billion = 1555 secs
• or just 25 minutes!!!

dictionary

• Have a corpus of common passwords
• If any digest matches, you know the input password

rainbow tables

Salting

password123

8640bd46

digest

input

Salting

• Salts are public, stored as plaintext
• Every user has a different, random salt

Salting

why is this better?

• You have to try every combination on each user 
• a hit only applies to one user

password123

7fc7c392

e73f51aa

password123

a778eef2

53026489

password123

b8d12a9a

160bba71

user 1:

user 2:

user 3:

Slow Hash Algorithms

MD5 vs bcrypt

• MD5​
  • Designed to be fast and efficient
  • GPU accelerated
• bcrypt
  • Designed to be slow and resource intensive
  • CPU only (can't be accelerated)

MD5 vs bcrypt

Case Study

Ashley Madison used bcrypt

Lessons

• Many sites are dumb enough to store plaintext passwords
• Even if hashed, they are still vulnerable to being cracked
• Even if using the best tools, human error (stupidity) can leave you and your password vulnerable.  

/giphy shrug

fin.