Yesterday I wrote a post about disabling SSLv3 in Postfix and today we take a close look at Apache. While taking a closer look at the current installation of Apache and the version shipped with Debian 8 that was released a few days back it showed that or the Apache project or Debian has taken the responsibility to completely disable SSLv2. Hopefully SSLv3 will get the same treatment soon, as broken security is worse than no security due to the false sense of security.
First we see that the cipher suite are different between both and for now I’ll ignore them. Those will be touched in a later posting as RC4 also needs to be phased-out. For Debian Jessie installations everything is well on protocol level, but for Wheezy the option “-SSLv3” is missing and since TLS is compiled into Apache and OpenSSL on Debian Wheezy it is pretty safe to turn SSLv3 off unless you want to keep servicing Internet Explorer 6.
SSLProtocol all -SSLv3 -SSLv2
As with Postfix also for Apache a hard restart to enforce this on all connection from that point forward to make sure no one keeps an old connection with SSLv3.
$ sudo systemctl restart apache2.service
Keep in mind that these setting can be set also on a virtual host level within Apache and will override any global setting. So it may be wise to also verify other configuration files for Apache and/or run sslscan against your websites to verify the SSL protocol offered.
The POODLE attack was made public late 2014 and as most vendors have taken action to solve possible issues related to POODLE. The time definitely has come to close SSLv3 in all parts of public facing infrastructure. By default Postfixstill only disallows SSLv2 and hopefully this will change in the form of stricter default behaviour in Postfix or distributions/vendors that stop shipping SSLv3 libraries.
For now you can set with the postconf command restrictions which protocols shouldn’t be used by Postfix.
As this is a change to /etc/postfix/main.cf Postfix can be reloaded to reread the configuration, but it may be smarter to just restart Postfix to make it effective for all connection from the moment Postfix restarts.
$ sudo systemctl restart postfix.service
All encrypted sessions Postfix allows will require TLSv1+. The next step will be to disable the RC4 cipher suite, but will do that in another posting.