alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Possible Fake AV Checkin"; flow:established,to_server; http.method; content:"POST"; nocase; http.uri; content:".php"; http.user_agent; content:"Mozilla/4.0 (compatible|3b 20|MSIE 6.0|3b 20|Windows NT 5.0)"; endswith; http.request_body; content:"data="; fast_pattern; depth:5; pcre:"/^data=[a-zA-Z0-9+\/]{64}/"; http.header_names; content:!"Referer"; classtype:command-and-control; sid:2011912; rev:9; metadata:created_at 2010_11_09, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_09_15;)