alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET CHAT MSN IM Poll via HTTP"; flow:established,to_server; content:"/gateway/gateway.dll?Action=poll&SessionID="; http_uri; nocase; threshold:type limit, track by_src, count 10, seconds 3600; classtype:policy-violation; sid:2001682; rev:10; metadata:created_at 2010_07_30, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)