ET EXPLOIT Unknown Target Application Command Injection Inbound

alert http any any -> [$HOME_NET,$HTTP_SERVERS] any (
    msg:"ET EXPLOIT Unknown Target Application Command Injection Inbound";
    flow:established,to_server;
    http.method;
    content:"GET";
    http.uri;
    content:"/nrdh.php?cmd"; fast_pattern;
    content:"="; distance:0; within:3;
    pcre:"/^.{0,5}(?:\x3b|\x0a|\x26|\x60|\x7C|\x24)/R";
    classtype:attempted-admin;
    sid:2033759; rev:1;
    metadata:attack_target Server, created_at 2021_08_22, deployment Perimeter, deployment Internal, confidence Medium, signature_severity Major, tag Exploit, updated_at 2021_08_22, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application;
)