ET WEB_CLIENT Generic Webshell Password Prompt Accessed on External Compromised Server

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET WEB_CLIENT Generic Webshell Password Prompt Accessed on External Compromised Server";
    flow:established,to_client;
    file_data;
    content:"<form method=post>password<br><input type=password name=pass style=|22|background-color:whitesmoke|3b|border:1px solid #fff|3b|outline:none|3b|' required>";
    content:"<input type=submit name=|22|watching|22 20|value=|22|submit|22 20|style=|22|border:none|3b|background-color:#56ad15|3b|color:#fff|3b|cursor:pointer|3b 22|></form>"; distance:0; fast_pattern;
    classtype:web-application-attack;
    sid:2029890; rev:2;
    metadata:affected_product Web_Server_Applications, attack_target Web_Server, created_at 2020_04_13, deployment Perimeter, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_04_13;
)