alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET ATTACK_RESPONSE ASP.NET Web BackDoor Webshell Title Banner Observed"; flow:established,to_client; http.stat_code; content:"200"; http.response_body; content:"|3C|title|3E|ASP.NET Web BackDoor|3C|/title|3E|"; fast_pattern; reference:url,github.com/tennc/webshell/blob/master/net-friend/aspx/Aspx%EF%BC%88%E5%85%8D%E6%9D%80%EF%BC%89.aspx; reference:url,blog.talosintelligence.com/uat-8099-chinese-speaking-cybercrime-group-seo-fraud/; classtype:trojan-activity; sid:2068142; rev:1; metadata:affected_product Microsoft_IIS, attack_target Web_Server, tls_state TLSDecrypt, created_at 2026_03_10, deployment Perimeter, malware_family Web_BackDoor, performance_impact Low, confidence High, signature_severity Major, tag WebShell, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2026_03_10, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1105, mitre_technique_name Ingress_Tool_Transfer; target:src_ip;)