alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed MSIL/Heracles Variant CnC Domain (stainless .fun in TLS SNI)"; flow:established,to_server; tls.sni; content:"stainless.fun"; bsize:13; fast_pattern; reference:md5,e0c6208936aa0cccd6867214145433b3; reference:url,tria.ge/210728-48w5bjla3x; classtype:domain-c2; sid:2033593; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2021_07_28, deployment Perimeter, malware_family MSIL_Heracles, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_07_28, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)