How to disable TLS 1.1 & 1.2 in Apache?
Solution 1:
Intrigued by this bug (and yes, I've been able to reproduce it) I've taken a look at the source code for the latest stable version of mod_ssl and found an explanation. Bear with me, this is gonna get amateur-stack-overflowish:
When the SSLProtocol has been parsed, it results in a char looking something like this:
0 1 0 0
^ ^ ^ ^
| | | SSLv1
| | SSLv2
| SSLv3
TLSv1
Upon initiating a new server context, ALL available protocols will be enabled, and the above char is inspected using some nifty bitwise AND operations to determine what protocols should be disabled. In this case, where SSLv3 is the only protocol to have been explicitly enabled, the 3 others will be disabled.
OpenSSL supports a protocol setting for TLSv1.1, but since the SSLProtocol does not account for this options, it never gets disabled. OpenSSL v1.0.1 has some known issues with TLSv1.2 but if it's supported I suppose the same goes for that as for TLSv1.1; it's not recognized/handled by mod_ssl and thus never disabled.
Source Code References for mod_ssl:
SSLProtocol gets parsed at line 925 in pkg.sslmod/ssl_engine_config.c
The options used in the above function is defined at line 444 in pkg.sslmod/mod_ssl.h
All protocols gets enabled at line 586 in pkg.sslmod/ssl_engine_init.c whereafter specific protocols gets disabled on the subsequent lines
How to disable it then?
You have a few options:
- Disable it in the OpenSSL config file with:
Protocols All,-TLSv1.1,-TLSv1.2 - Rewrite
mod_ssl;-)
Solution 2:
The issue is also addressed at the comments on the mod_ssl Apache page: http://httpd.apache.org/docs/2.2/mod/mod_ssl.html#comment_1136
If Ubuntu 12.04 had Apache 2.2.23, the problem would not have occurred. According to the comments, it is possible to enable TLSv1.1 and TLSv1.2, but TLSv1.0 is then enabled as well:
SSLProtocol All -SSLv2 -SSLv3