[Bro] Implementing a new script

Connor Borchgrevink borchgrevink at aggienetwork.com
Tue Jul 12 12:26:34 PDT 2016

Howdy all,

I recently began poking around Bro and had my first attempt of writing a 
script. The purpose of it was to detect whether or not traffic on port 
443 used SSL, the moment I implemented the script my CPU usage was at 
100% and the same happened to my memory. Without the script enabled, the 
machine runs fine and bro only uses about 50-60% of the resources. I 
also tried to turn off every other thing in local.bro but it was the 
same result. The code is as follows (be warned its pretty rough):

@load base/protocols/ssl
@load base/frameworks/notice
@load base/protocols/conn
@load base/utils/directions-and-hosts

module conn;

export {
         redef enum Notice::Type += {

         const List_of_Hosts = LOCAL_HOSTS &redef;
         const Encryption = "SSL" &redef;

event new_connection(c: connection) &priority=3
         if ( ! addr_matches_host(c$id$resp_h, List_of_Hosts) )

         local port_number=c$conn$id$resp_p;
         local ip_address=c$conn$id$resp_h;
         local encrypted=c$conn$service;

         if ( port_number != 443/tcp )

         if ( encrypted != Encryption )
                         $msg=fmt("Unencrypted traffic"),
                         $identifier=cat(c$id$resp_h, c$id$resp_p)

It is probably something I am not catching in my code or a limited 
knowledge of bro, but any help is much appreciated.


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