If you have ever worked in security operations before you should be pretty familiar with the daily pains of trying to detect and stop malware before it gets into your network environment. Theres plenty of sources out there to help you out. Last year I toyed with the concept of correlating my Snort alert sources with the spamhaus DNS blacklist. The results were pretty much what I expected. A lot of the unsolicited attacks and probes picked up by my IDS were coming from hosts that were on the spamhaus black list. This is presumably because the same hosts on botnets that are sending spam are also scanning for other victims and hosting malicious client side exploits. This really isn't 'news' - but what I find disturbing is that there doesn't seem to be any correlation in some of these defenses. Specifically, when my mail filter rejects a spam due to a hit on Spamhaus XBL (exploits/trojans list etc...), it stops. Why not send that offending IP to my firewall and blacklist it? I know there are IDS's that will send this type of information to the firewall when an alert is triggered. Are there any anti-spam technologies out there doing this? If any big anti-spam vendors start doing this, be sure to send me consulting work :)
I updated the Spamhaus-Snort correlation script today. I hope you find it useful.