alert dns $HOME_NET any -> any any (msg:"ET INFO External IP Lookup Domain in DNS Lookup (ipcalf .com)"; dns.query; bsize:10; content:"ipcalf.com"; nocase; reference:url,github.com/chubin/awesome-console-services; classtype:external-ip-check; sid:2054138; rev:1; metadata:affected_product Any, attack_target Client_Endpoint, created_at 2024_06_28, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag External_IP_Lookup, updated_at 2024_06_28, reviewed_at 2024_10_04, mitre_tactic_id TA0007, mitre_tactic_name Discovery, mitre_technique_id T1614, mitre_technique_name System_Location_Discovery;)