alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO DYNAMIC_DNS HTTP Request to a *.dyndns.* domain"; flow:established,to_server; http.host; content:".dyndns."; fast_pattern; content:!"checkip."; depth:8; content:!"update."; depth:7; pcre:"/\.dyndns\.(biz|info|org|tv)$/"; classtype:bad-unknown; sid:2013097; rev:16; metadata:attack_target Client_and_Server, created_at 2011_06_22, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, updated_at 2024_12_01, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1568, mitre_technique_name Dynamic_Resolution;)