Why doesn't this work to fix POODLE in Dovecot 2.0?

Question

Why doesn't this work to fix POODLE in Dovecot 2.0?

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forum:dee4 10 years, 2 months ago

I'm on Ubuntu 12.04 and the latest version of Dovecot it has is 2.0.19. It doesn't go up to 2.1.

According to

https://www.linode.com/docs/security/se … for-poodle">https://www.linode.com/docs/security/security-patches/disabling-sslv3-for-poodle

there is no easy way to patch Dovecot 2.0 for Poodle (I supposedly have to change Dovecot's source code).

According to another website

https://zmap.io/sslv3/servers.html#dovecot

this line should work for Dovecot 2.0:

ssl_cipher_list = ALL:!LOW:!SSLv2:!SSLv3:!EXP:!aNULL

It makes a lot of sense. It also does seem to work, in the sense that "openssl s_client -connect mail.example.com:993 -ssl3" gives me the right output according to the above Linode doc.

The problem is that my Mail.app client on OS X Yosemite can no longer connect to my mail server.

Why is this? Is this a problem with the Dovecot fix, or is it a problem with Mail.app?

3 Replies

forum:Main Street James · Answer 1 · Oct. 19, 2014, 1:38 p.m.

forum:Main Street James 10 years, 2 months ago

The problem is probably that Mail requires SSLv3.

Read more, and check sites & ports, at: http://poodlebleed.com

dwfreed · Answer 2 · Oct. 19, 2014, 4:09 p.m.

dwfreed 10 years, 2 months ago

TLS 1.0 and TLS 1.1 do not define any new ciphers, and so use the SSLv3 ciphers. Since you're disabling the SSLv3 ciphers, the only thing left is the TLS 1.2 ciphers. I don't have Yosemite yet, but Mavericks' Mail.app reports its highest supported TLS version is 1.0, even though the system crypto library supports TLS 1.2, which I found from dissecting the ClientHello in the TLS handshake. As a result, there are no ciphers the client supports in the server's provided cipher list, so the connection cannot continue.

IIRC, Wireshark can dissect the TLS handshake, and tell you the client's maximum supported TLS version. If Yosemite's Mail.app is also showing TLS 1.0 or 1.1 as the maximum supported version, then your options are to patch Dovecot yourself (not fun), wait until Ubuntu has released a patched version of Dovecot for 12.04 (see https://bugs.launchpad.net/ubuntu/+sour … ug/1381537">https://bugs.launchpad.net/ubuntu/+source/dovecot/+bug/1381537), or update to 14.04 (there are a lot of changes, so this won't be a simple upgrade).

forum:centminmod · Answer 3 · Oct. 19, 2014, 9:20 p.m.

what dwfreed said

reason why -SSLv3 doesn't work at cipher level is because OpenSSL tags TLSv1 as SSLv3 ciphers ~~[https://community.centminmod.com/threads/poodle-attacks-on-sslv3-vulnerability.1651/page-3#post-8189" target="_blank">](https://community.centminmod.com/thread … #post-8189">https://community.centminmod.com/threads/poodle-attacks-on-sslv3-vulnerability.1651/page-3#post-8189](. So if you try to disable SSLv3 at cipher level, you end up disabling TLSv1 too.

Hence SSLv3 needs to be disabled at SSL protocol level only which Linode suggests at https://www.linode.com/docs/security/se … for-poodle">https://www.linode.com/docs/security/security-patches/disabling-sslv3-for-poodle i.e. for dovecot

ssl_protocols = !SSLv2 !SSLv3

list of TLSv1 ciphers

openssl ciphers -v 'TLSv1' | sort
ADH-AES128-SHA          SSLv3 Kx=DH       Au=None Enc=AES(128)  Mac=SHA1
ADH-AES256-SHA          SSLv3 Kx=DH       Au=None Enc=AES(256)  Mac=SHA1
ADH-CAMELLIA128-SHA     SSLv3 Kx=DH       Au=None Enc=Camellia(128) Mac=SHA1
ADH-CAMELLIA256-SHA     SSLv3 Kx=DH       Au=None Enc=Camellia(256) Mac=SHA1
ADH-DES-CBC3-SHA        SSLv3 Kx=DH       Au=None Enc=3DES(168) Mac=SHA1
ADH-DES-CBC-SHA         SSLv3 Kx=DH       Au=None Enc=DES(56)   Mac=SHA1
ADH-RC4-MD5             SSLv3 Kx=DH       Au=None Enc=RC4(128)  Mac=MD5
ADH-SEED-SHA            SSLv3 Kx=DH       Au=None Enc=SEED(128) Mac=SHA1
AECDH-AES128-SHA        SSLv3 Kx=ECDH     Au=None Enc=AES(128)  Mac=SHA1
AECDH-AES256-SHA        SSLv3 Kx=ECDH     Au=None Enc=AES(256)  Mac=SHA1
AECDH-DES-CBC3-SHA      SSLv3 Kx=ECDH     Au=None Enc=3DES(168) Mac=SHA1
AECDH-NULL-SHA          SSLv3 Kx=ECDH     Au=None Enc=None      Mac=SHA1
AECDH-RC4-SHA           SSLv3 Kx=ECDH     Au=None Enc=RC4(128)  Mac=SHA1
AES128-SHA              SSLv3 Kx=RSA      Au=RSA  Enc=AES(128)  Mac=SHA1
AES256-SHA              SSLv3 Kx=RSA      Au=RSA  Enc=AES(256)  Mac=SHA1
CAMELLIA128-SHA         SSLv3 Kx=RSA      Au=RSA  Enc=Camellia(128) Mac=SHA1
CAMELLIA256-SHA         SSLv3 Kx=RSA      Au=RSA  Enc=Camellia(256) Mac=SHA1
DES-CBC3-SHA            SSLv3 Kx=RSA      Au=RSA  Enc=3DES(168) Mac=SHA1
DES-CBC-SHA             SSLv3 Kx=RSA      Au=RSA  Enc=DES(56)   Mac=SHA1
DH-DSS-AES128-SHA       SSLv3 Kx=DH/DSS   Au=DH   Enc=AES(128)  Mac=SHA1
DH-DSS-AES256-SHA       SSLv3 Kx=DH/DSS   Au=DH   Enc=AES(256)  Mac=SHA1
DH-DSS-CAMELLIA128-SHA  SSLv3 Kx=DH/DSS   Au=DH   Enc=Camellia(128) Mac=SHA1
DH-DSS-CAMELLIA256-SHA  SSLv3 Kx=DH/DSS   Au=DH   Enc=Camellia(256) Mac=SHA1
DH-DSS-DES-CBC3-SHA     SSLv3 Kx=DH/DSS   Au=DH   Enc=3DES(168) Mac=SHA1
DH-DSS-DES-CBC-SHA      SSLv3 Kx=DH/DSS   Au=DH   Enc=DES(56)   Mac=SHA1
DH-DSS-SEED-SHA         SSLv3 Kx=DH/DSS   Au=DH   Enc=SEED(128) Mac=SHA1
DHE-DSS-AES128-SHA      SSLv3 Kx=DH       Au=DSS  Enc=AES(128)  Mac=SHA1
DHE-DSS-AES256-SHA      SSLv3 Kx=DH       Au=DSS  Enc=AES(256)  Mac=SHA1
DHE-DSS-CAMELLIA128-SHA SSLv3 Kx=DH       Au=DSS  Enc=Camellia(128) Mac=SHA1
DHE-DSS-CAMELLIA256-SHA SSLv3 Kx=DH       Au=DSS  Enc=Camellia(256) Mac=SHA1
DHE-DSS-RC4-SHA         SSLv3 Kx=DH       Au=DSS  Enc=RC4(128)  Mac=SHA1
DHE-DSS-SEED-SHA        SSLv3 Kx=DH       Au=DSS  Enc=SEED(128) Mac=SHA1
DHE-RSA-AES128-SHA      SSLv3 Kx=DH       Au=RSA  Enc=AES(128)  Mac=SHA1
DHE-RSA-AES256-SHA      SSLv3 Kx=DH       Au=RSA  Enc=AES(256)  Mac=SHA1
DHE-RSA-CAMELLIA128-SHA SSLv3 Kx=DH       Au=RSA  Enc=Camellia(128) Mac=SHA1
DHE-RSA-CAMELLIA256-SHA SSLv3 Kx=DH       Au=RSA  Enc=Camellia(256) Mac=SHA1
DHE-RSA-SEED-SHA        SSLv3 Kx=DH       Au=RSA  Enc=SEED(128) Mac=SHA1
DH-RSA-AES128-SHA       SSLv3 Kx=DH/RSA   Au=DH   Enc=AES(128)  Mac=SHA1
DH-RSA-AES256-SHA       SSLv3 Kx=DH/RSA   Au=DH   Enc=AES(256)  Mac=SHA1
DH-RSA-CAMELLIA128-SHA  SSLv3 Kx=DH/RSA   Au=DH   Enc=Camellia(128) Mac=SHA1
DH-RSA-CAMELLIA256-SHA  SSLv3 Kx=DH/RSA   Au=DH   Enc=Camellia(256) Mac=SHA1
DH-RSA-DES-CBC3-SHA     SSLv3 Kx=DH/RSA   Au=DH   Enc=3DES(168) Mac=SHA1
DH-RSA-DES-CBC-SHA      SSLv3 Kx=DH/RSA   Au=DH   Enc=DES(56)   Mac=SHA1
DH-RSA-SEED-SHA         SSLv3 Kx=DH/RSA   Au=DH   Enc=SEED(128) Mac=SHA1
ECDH-ECDSA-AES128-SHA   SSLv3 Kx=ECDH/ECDSA Au=ECDH Enc=AES(128)  Mac=SHA1
ECDH-ECDSA-AES256-SHA   SSLv3 Kx=ECDH/ECDSA Au=ECDH Enc=AES(256)  Mac=SHA1
ECDH-ECDSA-DES-CBC3-SHA SSLv3 Kx=ECDH/ECDSA Au=ECDH Enc=3DES(168) Mac=SHA1
ECDH-ECDSA-NULL-SHA     SSLv3 Kx=ECDH/ECDSA Au=ECDH Enc=None      Mac=SHA1
ECDH-ECDSA-RC4-SHA      SSLv3 Kx=ECDH/ECDSA Au=ECDH Enc=RC4(128)  Mac=SHA1
ECDHE-ECDSA-AES128-SHA  SSLv3 Kx=ECDH     Au=ECDSA Enc=AES(128)  Mac=SHA1
ECDHE-ECDSA-AES256-SHA  SSLv3 Kx=ECDH     Au=ECDSA Enc=AES(256)  Mac=SHA1
ECDHE-ECDSA-DES-CBC3-SHA SSLv3 Kx=ECDH     Au=ECDSA Enc=3DES(168) Mac=SHA1
ECDHE-ECDSA-NULL-SHA    SSLv3 Kx=ECDH     Au=ECDSA Enc=None      Mac=SHA1
ECDHE-ECDSA-RC4-SHA     SSLv3 Kx=ECDH     Au=ECDSA Enc=RC4(128)  Mac=SHA1
ECDHE-RSA-AES128-SHA    SSLv3 Kx=ECDH     Au=RSA  Enc=AES(128)  Mac=SHA1
ECDHE-RSA-AES256-SHA    SSLv3 Kx=ECDH     Au=RSA  Enc=AES(256)  Mac=SHA1
ECDHE-RSA-DES-CBC3-SHA  SSLv3 Kx=ECDH     Au=RSA  Enc=3DES(168) Mac=SHA1
ECDHE-RSA-NULL-SHA      SSLv3 Kx=ECDH     Au=RSA  Enc=None      Mac=SHA1
ECDHE-RSA-RC4-SHA       SSLv3 Kx=ECDH     Au=RSA  Enc=RC4(128)  Mac=SHA1
ECDH-RSA-AES128-SHA     SSLv3 Kx=ECDH/RSA Au=ECDH Enc=AES(128)  Mac=SHA1
ECDH-RSA-AES256-SHA     SSLv3 Kx=ECDH/RSA Au=ECDH Enc=AES(256)  Mac=SHA1
ECDH-RSA-DES-CBC3-SHA   SSLv3 Kx=ECDH/RSA Au=ECDH Enc=3DES(168) Mac=SHA1
ECDH-RSA-NULL-SHA       SSLv3 Kx=ECDH/RSA Au=ECDH Enc=None      Mac=SHA1
ECDH-RSA-RC4-SHA        SSLv3 Kx=ECDH/RSA Au=ECDH Enc=RC4(128)  Mac=SHA1
EDH-DSS-DES-CBC3-SHA    SSLv3 Kx=DH       Au=DSS  Enc=3DES(168) Mac=SHA1
EDH-DSS-DES-CBC-SHA     SSLv3 Kx=DH       Au=DSS  Enc=DES(56)   Mac=SHA1
EDH-RSA-DES-CBC3-SHA    SSLv3 Kx=DH       Au=RSA  Enc=3DES(168) Mac=SHA1
EDH-RSA-DES-CBC-SHA     SSLv3 Kx=DH       Au=RSA  Enc=DES(56)   Mac=SHA1
EXP1024-DES-CBC-SHA     SSLv3 Kx=RSA(1024) Au=RSA  Enc=DES(56)   Mac=SHA1 export
EXP1024-DHE-DSS-DES-CBC-SHA SSLv3 Kx=DH(1024) Au=DSS  Enc=DES(56)   Mac=SHA1 export
EXP1024-DHE-DSS-RC4-SHA SSLv3 Kx=DH(1024) Au=DSS  Enc=RC4(56)   Mac=SHA1 export
EXP1024-RC4-SHA         SSLv3 Kx=RSA(1024) Au=RSA  Enc=RC4(56)   Mac=SHA1 export
EXP-ADH-DES-CBC-SHA     SSLv3 Kx=DH(512)  Au=None Enc=DES(40)   Mac=SHA1 export
EXP-ADH-RC4-MD5         SSLv3 Kx=DH(512)  Au=None Enc=RC4(40)   Mac=MD5  export
EXP-DES-CBC-SHA         SSLv3 Kx=RSA(512) Au=RSA  Enc=DES(40)   Mac=SHA1 export
EXP-DH-DSS-DES-CBC-SHA  SSLv3 Kx=DH/DSS   Au=DH   Enc=DES(40)   Mac=SHA1 export
EXP-DH-RSA-DES-CBC-SHA  SSLv3 Kx=DH/RSA   Au=DH   Enc=DES(40)   Mac=SHA1 export
EXP-EDH-DSS-DES-CBC-SHA SSLv3 Kx=DH(512)  Au=DSS  Enc=DES(40)   Mac=SHA1 export
EXP-EDH-RSA-DES-CBC-SHA SSLv3 Kx=DH(512)  Au=RSA  Enc=DES(40)   Mac=SHA1 export
EXP-RC2-CBC-MD5         SSLv3 Kx=RSA(512) Au=RSA  Enc=RC2(40)   Mac=MD5  export
EXP-RC4-MD5             SSLv3 Kx=RSA(512) Au=RSA  Enc=RC4(40)   Mac=MD5  export
IDEA-CBC-SHA            SSLv3 Kx=RSA      Au=RSA  Enc=IDEA(128) Mac=SHA1
NULL-MD5                SSLv3 Kx=RSA      Au=RSA  Enc=None      Mac=MD5
NULL-SHA                SSLv3 Kx=RSA      Au=RSA  Enc=None      Mac=SHA1
PSK-3DES-EDE-CBC-SHA    SSLv3 Kx=PSK      Au=PSK  Enc=3DES(168) Mac=SHA1
PSK-AES128-CBC-SHA      SSLv3 Kx=PSK      Au=PSK  Enc=AES(128)  Mac=SHA1
PSK-AES256-CBC-SHA      SSLv3 Kx=PSK      Au=PSK  Enc=AES(256)  Mac=SHA1
PSK-RC4-SHA             SSLv3 Kx=PSK      Au=PSK  Enc=RC4(128)  Mac=SHA1
RC4-MD5                 SSLv3 Kx=RSA      Au=RSA  Enc=RC4(128)  Mac=MD5
RC4-SHA                 SSLv3 Kx=RSA      Au=RSA  Enc=RC4(128)  Mac=SHA1
SEED-SHA                SSLv3 Kx=RSA      Au=RSA  Enc=SEED(128) Mac=SHA1
SRP-3DES-EDE-CBC-SHA    SSLv3 Kx=SRP      Au=SRP  Enc=3DES(168) Mac=SHA1
SRP-AES-128-CBC-SHA     SSLv3 Kx=SRP      Au=SRP  Enc=AES(128)  Mac=SHA1
SRP-AES-256-CBC-SHA     SSLv3 Kx=SRP      Au=SRP  Enc=AES(256)  Mac=SHA1
SRP-DSS-3DES-EDE-CBC-SHA SSLv3 Kx=SRP      Au=DSS  Enc=3DES(168) Mac=SHA1
SRP-DSS-AES-128-CBC-SHA SSLv3 Kx=SRP      Au=DSS  Enc=AES(128)  Mac=SHA1
SRP-DSS-AES-256-CBC-SHA SSLv3 Kx=SRP      Au=DSS  Enc=AES(256)  Mac=SHA1
SRP-RSA-3DES-EDE-CBC-SHA SSLv3 Kx=SRP      Au=RSA  Enc=3DES(168) Mac=SHA1
SRP-RSA-AES-128-CBC-SHA SSLv3 Kx=SRP      Au=RSA  Enc=AES(128)  Mac=SHA1
SRP-RSA-AES-256-CBC-SHA SSLv3 Kx=SRP      Au=RSA  Enc=AES(256)  Mac=SHA1

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Why doesn't this work to fix POODLE in Dovecot 2.0?

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