alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Cobalt Strike Malleable C2 (Custom)"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/api/2.0/modules?"; startswith; fast_pattern; http.header_names; content:!"Referer"; http.header; content:"Content-Type|3a 20|application/x-www-form-urlencoded|0d 0a|Accept|3a 20|*/*|0d 0a|Content-Transfer-Encoding|3a 20|base64|0d 0a|"; http.request_body; pcre:"/^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/"; reference:url,twitter.com/CyberRaiju/status/1249272772963864576; reference:md5,79bbe1365fb7532613823ce3e0cac499; classtype:command-and-control; sid:2029978; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_04_20, deployment Perimeter, malware_family Cobalt_Strike, confidence Medium, signature_severity Major, updated_at 2020_04_20, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1001, mitre_technique_name Data_Obfuscation;)