modernize default smtp_deliver TLS options

Author: Brent Cook

lib/msf/core/exploit/smtp_deliver.rb

@@ -228,12 +228,9 @@ def swap_sock_plain_to_ssl(nsock=self.sock)
   end
 
   def generate_ssl_context
-    ctx = OpenSSL::SSL::SSLContext.new
-    ctx.key = OpenSSL::PKey::RSA.new(1024){ }
-
-    ctx.session_id_context = Rex::Text.rand_text(16)
-
-    return ctx
+    ctx = OpenSSL::SSL::SSLContext.new(:SSLv23)
+    ctx.ciphers = "ALL:!ADH:!EXPORT:!SSLv2:!SSLv3:+HIGH:+MEDIUM"
+    ctx
   end
 
 end