1.5.78. How to Manage SSL Protocols and Ciphers used with Virtuoso?
What?
As of Virtuoso 7.2, SSL protocol and cipher support is now configurable for connections from all HTTP, ODBC, JDBC, ADO.NET, and OLE-DB clients.
Why?
Default binding to OpenSSL can expose Virtuoso instances to version- and cipher-specific SSL vulnerabilities (e.g., recent Poodle exploit ). Being able to scope Virtuoso's use of SSL to one or more specific versions provides instance administrators better protection against a moving target.
How?
Basic SSL Protocol Configuration
Basic configuration is through the SSL_Protocols
values in the [Parameters]
and
[HTTP]
sections of the Virtuoso INI file. These are comma+space-separated (", ") value lists. Including a
protocol name explicitly enables it; preceding the protocol name with an exclamation point ("!
")
explicitly disables it.
Basic SSL Protocol Configuration
Table 1.1. Supported SSL Protocols and INI keyword values List
| SSL/TLS Version | Value for INI file | Notes |
|---|---|---|
| SSLv2 | - | Permanently disabled. |
| SSLv3 |
SSLv3
|
Disabled by default. To our knowledge, only required by IE6/Windows XP clients. |
| TLSv1 |
TLSv1
|
Enabled by default. |
| TLSv1.1 |
TLSv1.1
|
Enabled by default, supported if available in local openssl
library. |
| TLSv1.2 |
TLSv1.2
|
Enabled by default, supported if available in local openssl
library. |
Advanced SSL Cipher List Configuration
The SSL_Cipher_List
values in the [Parameters]
and [HTTP]
stanzas of the
Virtuoso INI file may also be adjusted, to disable particular ciphers when there are security reports about some new
attack that breaks them. These are colon-separated (":
") value lists.
Including a protocol name or groupname explicitly enables it; preceding the protocol name with an exclamation point
("!
") explicitly disables it. You can review the ciphers supported by your local OpenSSL
library
with the command:
openssl ciphers -v ALL
For instance, we recommend explicitly forbidding anonymous cipher suites (i.e., ones that do not use certificates,
and are therefore susceptible to man-in-the-middle attacks) using !aNULL
.
We also recommend including @STRENGTH
at the end of the list, so that OpenSSL
will
prioritize the enabled ciphers by key length, regardless of the list order.
Recommended Settings
The sample settings below provide a reasonable tradeoff of security versus flexibility. As shown, we have enabled
SSLv3
on the HTTPS ports for IE6 users, but left this disabled on the SQL data port.
[Parameters] SSL_Protocols = TLSv1, TLSv1.1, TLSv1.2 SSL_Cipher_List = HIGH:!aNULL:!eNULL:!RC4:!DES:!MD5:!PSK:!SRP:!KRB5:!SSLv2:!EXP:!MEDIUM:!LOW:!DES-CBC-SHA:@STRENGTH [HTTP] SSL_Protocols = SSLv3, TLSv1, TLSv1.1, TLSv1.2 SSL_Cipher_List = HIGH:!aNULL:!eNULL:!RC4:!DES:!MD5:!PSK:!SRP:!KRB5:!SSLv2:!EXP:!MEDIUM:!LOW:!DES-CBC-SHA:@STRENGTH