alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE MuddyWater APT Related Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/protocol/function.php?page="; fast_pattern; startswith; http.header; content:!"Referer"; http.host; pcre:"/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/"; reference:url,blog.talosintelligence.com/2022/03/iranian-supergroup-muddywater.html; classtype:trojan-activity; sid:2035426; rev:2; metadata:attack_target Client_Endpoint, created_at 2022_03_10, deployment Perimeter, malware_family MuddyWater, malware_family TA453, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_05_02;)