alert http $HOME_NET any -> $EXTERNAL_NET 443 (msg:"ET MALWARE FormerFirstRAT HTTP POST CnC Beacon"; flow:established,to_server; urilen:1; http.method; content:"POST"; http.header; content:"|3a|443|0d 0a|"; http.user_agent; content:"Mozilla/4.0 (compatible|3b 20|MSIE 6.0|3b 20|Windows NT 5.0|3b 20|.NET CLR 1.1.4322)"; depth:69; endswith; fast_pattern; http.request_body; pcre:"/^[\x20-\x7e\r\n]{0,20}[^\x20-\x7e\r\n]/"; http.header_names; content:!"Accept-"; content:!"Referer|0d 0a|"; content:!"Content-Type|0d 0a|"; reference:url,researchcenter.paloaltonetworks.com/2015/04/unit-42-identifies-new-dragonok-backdoor-malware-deployed-against-japanese-targets/; classtype:command-and-control; sid:2020926; rev:5; metadata:attack_target Client_Endpoint, created_at 2015_04_16, deployment Perimeter, signature_severity Major, tag c2, updated_at 2020_10_14, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)