Wednesday, 13 March 2013

Nice write-up on issues in TLS/SSL

Haven't blogged in a while due to studying for the CISSP certification and working on other fun projects. Amazon EC2 instances are enormous fun to play with, and free to get started with, wish i had this type of stuff when i was in uni.

Came across this great story on RC4 and TLS:
Attack of the week: RC4 is kind of broken in TLS
Cipher suites in the TLS/SSL implementations have been an interesting area of late with a number of attacks being published in the last few months.
A fun thing to do is to scan a website using the TLSSLED shell script and see what cipher suites it supports.
Here's the output for google.com:

         Accepted  SSLv3  256 bits  ECDHE-RSA-AES256-SHA
    Accepted  SSLv3  256 bits  AES256-SHA
    Accepted  SSLv3  168 bits  ECDHE-RSA-DES-CBC3-SHA
    Accepted  SSLv3  168 bits  DES-CBC3-SHA
    Accepted  SSLv3  128 bits  ECDHE-RSA-AES128-SHA
    Accepted  SSLv3  128 bits  AES128-SHA
    Accepted  SSLv3  128 bits  ECDHE-RSA-RC4-SHA
    Accepted  SSLv3  128 bits  RC4-SHA
    Accepted  SSLv3  128 bits  RC4-MD5
    Accepted  TLSv1  256 bits  ECDHE-RSA-AES256-SHA
    Accepted  TLSv1  256 bits  AES256-SHA
    Accepted  TLSv1  168 bits  ECDHE-RSA-DES-CBC3-SHA
    Accepted  TLSv1  168 bits  DES-CBC3-SHA
    Accepted  TLSv1  128 bits  ECDHE-RSA-AES128-SHA
    Accepted  TLSv1  128 bits  AES128-SHA
    Accepted  TLSv1  128 bits  ECDHE-RSA-RC4-SHA
    Accepted  TLSv1  128 bits  RC4-SHA
    Accepted  TLSv1  128 bits  RC4-MD5

The interesting listing in this case is "RC4-MD5", considering the MD5 is considered broken and should have been retired by now. 

Compared this to api.square.com:443:

    Accepted  SSLv3  256 bits  AES256-SHA
    Accepted  SSLv3  168 bits  DES-CBC3-SHA
    Accepted  SSLv3  128 bits  AES128-SHA
    Accepted  SSLv3  128 bits  RC4-SHA
    Accepted  TLSv1  256 bits  AES256-SHA
    Accepted  TLSv1  168 bits  DES-CBC3-SHA
    Accepted  TLSv1  128 bits  AES128-SHA
    Accepted  TLSv1  128 bits  RC4-SHA
Which is in line with FIPS 140-2 Annex A.





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