Word is slowly coming through industry channels that the attackers in the Heartland breach exfiltrated sniffed data via an outbound network connection. While not surprising, I did hear that the connection wasn’t encrypted- the bad guys sent the data out in cleartext (I’ll leave it to the person who passed this on to identify themselves if they want). Rumor from 2 independent sources is the bad guys are an organized group out of St. Petersburg (yes, Russia, as cliche as that is).
This is similar to a whole host of breaches- including (probably) TJX. While I’m not so naive as to think you can stop all malicious outbound connections, I do think there’s a lot we can do to make life harder on the bad guys.
First, you need to lock down your outbound connections using a combination of current and next-generation firewalls. You should isolate out your transaction network to enforce tighter controls on it than on the rest of your business network. Traditional firewalls can lock down most outbound port/protocols, but struggle with nested/stealth channels or all the stuff shoveled over port 80. Next-gen firewalls and web gateways (I hate the name, but don’t have a better one) like Palo Alto Networks or Mi5 Networks can help. Regular web gateways (Websense and McAfee/Secure Computing) are also good, but vary more on their outbound control capabilities and tend to be more focused on malware prevention (not counting their DLP products, which we’ll talk about in a second).
The web gateway and next gen firewalls will focus on your overall network, while you can lock of the transaction side with tighter traditional firewall rules and segmenting that thing off.
Next, use DLP to sniff for outbound cardholder data. The bad guys don’t seem to be encrypting, and DLP will alert on that in a heartbeat (and maybe block it, depending on the channel). You’ll want to proxy with your web gateway to sniff SSL (and only some web gateways can do this) and set the DLP to alert on unauthorized encryption usage. That might be a real pain in the ass, if you have a lot of unmanaged encryption outside of SSL. Also, to do the outbound SSL proxy you need to roll out a gateway certificate to all your endpoints and suppress browser alerts via group policies.
I also recommend DLP content discovery to reduce where you have unencrypted stored data (yes, you do have it, even if you think you don’t).
As you’ve probably figured out by now, if you are starting from scratch some of this will be very difficult to implement on an existing network, especially one that hasn’t been managed tightly. Thus I suggest you focus on any of your processing/transaction paths and start walling those off first. In the long run, that will reduce both your risks and your compliance and audit costs.