dovecot - Mar 2015 - New FREAK SSL Attack CVE-2015-0204

On 04.03.2015 18:19, Emmanuel Dreyfus wrote:
> On Wed, Mar 04, 2015 at 06:13:31PM +0200, Adrian Minta wrote:
>> Hello,
>> about the CVE-2015-0204, in apache the following config seems to
disable
>> this vulnerability:
>>   SSLProtocol All -SSLv2 -SSLv3
>>   SSLCipherSuite
>> HIGH:MEDIUM:!aNULL:!eNULL:!EXPORT:!CAMELLIA:!DES:!MD5:!PSK:!RC4
>>
>> Is something similar possible with dovecot ?
> I use this with some succes:
>
> # dovecot has built-in protection against BEAST, therefore no need
> # to remove -SSLv2-SHA1:-TLSv10-SHA1
> ssl_protocols = !SSLv2 !SSLv3
> ssl_cipher_list = ECDH at STRENGTH:DH at
STRENGTH:HIGH:!RC4:!MD5:!DES:!aNULL:!eNULL
>
> I only had a single report of an old client being locked out. Oddly it
> was a recent Windows Phone that was perfectly capable of using
> latest protocol and ciphers.
>
> While there, I will self advertise my own paper on TLS hardening:
> http://arxiv.org/abs/1407.2168
>
Thank you for the answer.
The "!EXPORT" part is included in "ECDH at STRENGTH:DH at
STRENGTH:HIGH", or
it must be added as well ?

-- 
Best regards,
Adrian Minta

On Wed, Mar 04, 2015 at 06:36:07PM +0200, Adrian Minta
wrote:
> Thank you for the answer.
> The "!EXPORT" part is included in "ECDH at STRENGTH:DH at
STRENGTH:HIGH", or it
> must be added as well ?
This is not the cipher list I sent. It was:
ECDH at STRENGTH:DH at STRENGTH:HIGH:!RC4:!MD5:!DES:!aNULL:!eNUL

Mine does not contain any export cipher, yours does.
You can use openssl ciphers to compare cipher lists:

$ openssl ciphers EXPORT|tr ':' '\n' |sort > export
$ openssl ciphers ECDH at STRENGTH:DH at
STRENGTH:HIGH:!RC4:!MD5:!DES:!aNULL:!eNULL \
  |tr ':' '\n' |sort> manu
$ openssl ciphers ECDH at STRENGTH:DH at STRENGTH:HIGH |tr ':'
'\n' |sort > adrian
$ join export manu
(nothing)
$ join export adrian
EXP-ADH-DES-CBC-SHA
EXP-ADH-RC4-MD5
EXP-EDH-DSS-DES-CBC-SHA
EXP-EDH-RSA-DES-CBC-SHA


-- 
Emmanuel Dreyfus
manu at netbsd.org

On 04.03.2015 18:53, Emmanuel Dreyfus wrote:
> On Wed, Mar 04, 2015 at 06:36:07PM +0200, Adrian Minta wrote:
>> Thank you for the answer.
>> The "!EXPORT" part is included in "ECDH at STRENGTH:DH
at STRENGTH:HIGH", or it
>> must be added as well ?
> This is not the cipher list I sent. It was:
> ECDH at STRENGTH:DH at STRENGTH:HIGH:!RC4:!MD5:!DES:!aNULL:!eNUL
>
> Mine does not contain any export cipher, yours does.
> You can use openssl ciphers to compare cipher lists:
>
> $ openssl ciphers EXPORT|tr ':' '\n' |sort > export
> $ openssl ciphers ECDH at STRENGTH:DH at
STRENGTH:HIGH:!RC4:!MD5:!DES:!aNULL:!eNULL \
>    |tr ':' '\n' |sort> manu
> $ openssl ciphers ECDH at STRENGTH:DH at STRENGTH:HIGH |tr ':'
'\n' |sort > adrian
> $ join export manu
> (nothing)
> $ join export adrian
> EXP-ADH-DES-CBC-SHA
> EXP-ADH-RC4-MD5
> EXP-EDH-DSS-DES-CBC-SHA
> EXP-EDH-RSA-DES-CBC-SHA
>
>
I was using 
HIGH:MEDIUM:!aNULL:!eNULL:!EXPORT:!CAMELLIA:!DES:!MD5:!PSK:!RC4 in apache.
You are using 
ECDH at STRENGTH:DH at STRENGTH:HIGH:!RC4:!MD5:!DES:!aNULL:!eNULL for dovecot.

I didn't know how to compare both settings. Now I know, and I see that 
my "!EXPORT" part is covered by your "ECDH at STRENGTH:DH at
STRENGTH:HIGH" part.

$openssl ciphers 
HIGH:MEDIUM:\!aNULL:\!eNULL:\!EXPORT:\!CAMELLIA:\!DES:\!MD5:\!PSK:\!RC4 
| tr ':' '\n' |sort > /tmp/adrian
$openssl ciphers 
ECDH at STRENGTH:DH at STRENGTH:HIGH:\!RC4:\!MD5:\!DES:\!aNULL:\!eNULL | tr 
':' '\n' |sort > /tmp/manu
$diff adrian manu
  6a7,8
  > CAMELLIA128-SHA
  > CAMELLIA256-SHA
  13a16,17
  > DHE-DSS-CAMELLIA128-SHA
  > DHE-DSS-CAMELLIA256-SHA
  20a25,26
  > DHE-RSA-CAMELLIA128-SHA
  > DHE-RSA-CAMELLIA256-SHA
  52c58,60
  < SEED-SHA
  ---
  > PSK-3DES-EDE-CBC-SHA
  > PSK-AES128-CBC-SHA
  > PSK-AES256-CBC-SHA

The main difference is the support for CAMELLIA and PSK. Unfortunately I 
don't now enough to say if is good or bad to support any of those two.


Thank you !

-- 
Best regards,
Adrian Minta