How to disable SSLv3

Revision as of 18:01, 15 October 2014 by Fmarques (talk | contribs)
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.
Admin Article

Article Information

This article applies to the following ZCS versions.

ZCS 8.0 Article ZCS 8.0 ZCS 8.5 Article ZCS 8.5

How to disable SSLv3

Due to the recent discovery of a new SSL vulnerability (CVE-2014-3566: Poodle SSLv3), this protocol has been considered unsafe. This is a protocol flaw and Zimbra might include patches or configuration changes in future releases. Please check existing Bug https://bugzilla.zimbra.com/show_bug.cgi?id=95976.

As a workaround, this guide will help you on how to disable SSLv3 with Zimbra. This has been tested on both ZCS 8.0.8 and 8.5.0 releases.

Postfix

8.5.x

zmprov mcf zimbraMtaSmtpdTlsProtocols '\!SSLv3'

8.0.x

postconf -e smtpd_tls_protocols=\!SSLv3

Run "zmmtactl stop ; zmmtactl start" to force the changes or wait for mailboxd to rewrite Postfix config from LDAP after 2 minutes.

If you are already disabling ciphers by following http://wiki.zimbra.com/wiki/Postfix_PCI_Compliance_in_ZCS, please also include SSLv3:

8.5.x

zmprov mcf zimbraMtaSmtpdTlsCiphers high zmprov mcf zimbraMtaSmtpdTlsProtocols '\!SSLv3,\!SSLv2,TLSv1,TLSv2' zmprov mcf zimbraMtaSmtpdTlsMandatoryCiphers high zmprov mcf zimbraMtaSmtpdTlsExcludeCiphers 'aNULL,MD5,DES'

8.0.x

zmlocalconfig -e smtpd_tls_ciphers=high postconf -e smtpd_tls_protocols=\!SSLv3,\!SSLv2,TLSv1,TLSv2 zmlocalconfig -e smtpd_tls_mandatory_ciphers=high postconf -e smtpd_tls_exclude_ciphers=aNULL,MD5,DES

Run "zmmtactl stop ; zmmtactl start" to apply the changes.

Note that smtpd_tls_protocols and smtpd_tls_exclude_ciphers will need to be set after every upgrade as there is no way to preserve them in ZCS 8.0 and previous.

Nginx

8.5.x

For https and Admin UI:

Please edit /opt/zimbra/conf/nginx/templates/nginx.conf.web.https.default.template

and include the following line under the servers { } configuration:

ssl_protocols TLSv1 TLSv1.1 TLSv1.2;

Example:

  1. HTTPS Proxy Default Configuration

server {

   ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
   ${core.ipboth.enabled}listen                  [::]:${web.https.port} default;

[...]

Apply the same change at /opt/zimbra/conf/nginx/templates/nginx.conf.web.admin.default.template

If you are using SSO with Client certificates, also edit /opt/zimbra/conf/nginx/templates/nginx.conf.web.sso.default.template.

For imaps and pop3s:

Please edit /opt/zimbra/conf/nginx/templates/nginx.conf.mail.pop3s.default.template

Example:

  1. POP3S proxy default configuration

server {

   ssl_protocols TLSv1 TLSv1.1 TLSv1.2;

[...]

Apply the same change at /conf/nginx/templates/nginx.conf.mail.imaps.default.template

Restart the proxy servers with: "zmproxyctl stop ; zmproxyctl start"

Jump to: navigation, search