alert dns $HOME_NET any -> any any (msg:"ET MALWARE ALFA Shell APT33 DNS Lookup (solevisible .com)"; dns.query; content:"solevisible.com"; nocase; endswith; threshold:type limit,count 1,track by_src,seconds 120; reference:url,fireeye.com/blog/threat-research/2017/09/apt33-insights-into-iranian-cyber-espionage.html; classtype:domain-c2; sid:2033095; rev:2; metadata:attack_target Client_Endpoint, created_at 2021_06_04, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_06_04;)