For you Snort Users:

alert tcp any any -> any any (msg:"Agobot/Phatbot Infection Successful"; flow:established; content:"221 Goodbye, have a good infection |3a 29 2e 0d 0a|"; dsize:40; classtype:trojan-activity; reference:url,www.lurhq.com/phatbot.html; sid:1000075; rev:1;)

alert tcp any any -> any any (msg:"Phatbot P2P Control Connection"; flow:established; content:"Wonk-"; content:"|00|#waste|00|"; within:15; classtype:trojan-activity; reference:url,www.lurhq.com/phatbot.html;
sid:1000076; rev:1;)

I would suggest this is best used on the internal sensors.