alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE RedFlick DNSObserver CnC Check-In"; reference:url,dslua.org/publications/spearphishing-via-fake-urc-2026-invitations-targets-ukrainian-csos/; reference:url,community.emergingthreats.net/t/sig-malware-redflick-dnsobserver-http-c2-check-in/3527; classtype:trojan-activity; sid:2072753; rev:1; metadata:affected_product Windows_Client, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2026_11_13, deployment Perimeter, deployment SSLDecrypt, malware_family RedFlick, confidence High, signature_severity Critical, tag c2, updated_at 2026_11_13, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)