alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Cobalt Strike Activity"; flow:established,to_server; http.method; content:"GET"; http.start; content:".js|20|HTTP/1.1|0d 0a|Cookie|3a 20|SSID="; fast_pattern; pcre:"/^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})\r\n/R"; reference:md5,653b45c576c89c00a164b51e23732957; reference:url,twitter.com/z0ul_/status/1374724622508245008; classtype:trojan-activity; sid:2032330; rev:1; metadata:attack_target Client_Endpoint, created_at 2021_03_25, deployment Perimeter, performance_impact Low, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_03_25;)