The Dog’s Biggest Bite
Overview
 History
 Start Communication
 Protocol Weakness
 POODLE
 Issues
History
 1994 – Netscape Communications Design SSL
 Version Never Released Publicly
 1995 – SSL 2.0 Release as Part of Netscape Navigator
 1996 – V3.0 Redesign of Protocol
 Address 2.0 Vulnerabilities
 First Version to Authenticate Handshake Messages

Prevents Attackers from Triggering Downgrade protocol
versions
 1999 – IETF Publishes TLS 1.0 Standard
Start Communication
 Handshake
 Agree on Shared Secret Key
 Includes

Cipher Algorithms
 Block Cipher Most Common Used
 If Both Cannot Agree On Protocol
 Downgrade Dance
Start Communication
 Handshake
 Client Hello


Information that the server needs to communicate with the
client using SSL.
Including SSL version number, cipher settings, sessionspecific data.
 Server Hello
 Information that the client needs to communicate with the
server using SSL.
 Including SSL version number, cipher settings, sessionspecific data.
 Including Server’s Certificate (Public Key)
Start Communication
 Authentication and Pre-Mater Secret



Client authenticates the server certificate. (e.g. Common
Name / Date / Issuer)
Client (depending on the cipher) creates the pre-master secret
for the session,
Encrypts with the server's public key and sends the encrypted
pre-master secret to the server
 Decryption and Master Secret


Server uses its private key to decrypt the pre-master secret,
Both Server and Client perform steps to generate the master
secret with the agreed cipher.
Start Communication
 Generate Session Keys

Both the client and the server use the master secret to
generate the session keys, which are symmetric keys used to
encrypt and decrypt information exchanged during the SSL
session
 Encryption with Session Keys

Both client and server exchange messages to inform that
future messages will be encrypted.
Protocol Weakness
 Today Agreement on Process to Produce
Authenticated Encrypted Data
 Not True When SSL was Created
 Today Encrypt-Then-Mac (Message Authentication
Code)
 SSL uses Mac-Then-Encrypt
POODLE
 POODLE –Padding Oracle On Downgraded Legacy
Encryption
 Attacker Takes Advantage of Downgrade Dance
 Works by Using Padding
 Padding is Created by Block Cipher
 Attacker Gets 1 byte out of Every 256 Requests
 Attacker Can Retrieve n Bytes of Data in 256 X n
Request
 Work as part of Man-In-The-Middle (MITM)
POODLE
Issues
 Turn Off SSL V3.0
 Could Lock Out 1% - 5% of Users (XP /IE 6)
 Must Achive MITM Before Using Attack Vector
 Exploit Not as Bad as HeartBleed, Implementation
Hard
References
 https://www.dfranke.us/posts/2014-10-14-how-poodle-




happened.html
http://www.theregister.co.uk/2014/10/16/poodle_analy
sis/
http://news.netcraft.com/archives/2014/10/15/googlespoodle-affects-oodles.html
http://www.symantec.com/connect/blogs/how-doesssl-work-what-ssl-handshake
http://security.stackexchange.com/questions/20803/h
ow-does-ssl-tls-work