alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET USER_AGENTS EmailSiphon Suspicious User-Agent Inbound"; flow:established,to_server; http.user_agent; content:"EmailSiphon"; nocase; startswith; reference:url,www.useragentstring.com/pages/useragentstring.php; classtype:attempted-recon; sid:2013032; rev:5; metadata:affected_product Any, attack_target Client_Endpoint, created_at 2011_06_14, deployment Perimeter, confidence High, signature_severity Major, tag User_Agent, updated_at 2024_04_13;)