alert http any any -> [$HOME_NET,$HTTP_SERVERS] any (msg:"ET MALWARE Webshell Execute Command Inbound - Possibly Iran-based M1"; flow:established,to_server; http.method; content:"POST"; http.request_body; content:"__VIEWSTATE="; startswith; content:"&txtAuthKey=20TyG6eQqEopbFMB&txtCommand="; fast_pattern; classtype:command-and-control; sid:2033419; rev:1; metadata:attack_target Server, created_at 2021_07_25, deployment Perimeter, confidence High, signature_severity Major, tag WebShell, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_07_25, mitre_tactic_id TA0003, mitre_tactic_name Persistence, mitre_technique_id T1505, mitre_technique_name Server_Software_Component;)