ET HUNTING Request for Webshell in .well-known directory

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET HUNTING Request for Webshell in .well-known directory";
    flow:established,to_server;
    http.uri;
    content:"/.well-known/"; fast_pattern; startswith;
    pcre:"/^.*?\x2e(?:php|cfm|cgi|asp|aspx|jsp|rb|sh|p[yl])/R";
    http.user_agent;
    content:!"let|27|s encrypt validation server"; nocase;
    reference:url,url,isc.sans.edu/diary/32320;
    classtype:misc-attack;
    sid:2064917; rev:2;
    metadata:affected_product Web_Server_Applications, attack_target Web_Server, tls_state plaintext, created_at 2025_09_25, deployment Perimeter, performance_impact Low, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2026_02_18, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1567, mitre_technique_name Exfiltration_Over_Web_Service;
    target:dest_ip;
)