alert http $EXTERNAL_NET any -> $HOME_NET any (
msg:"ET POLICY Externally Hosted Fortinet Endpoint Management Server (EMS) FortiClient Onboarding URI Scheme Observed";
flow:established,to_client;
http.response_body;
content:"fabricagent|3a 2f 2f|ems/onboarding?username="; fast_pattern;
reference:url,www.sonarsource.com/blog/caught-in-the-fortinet-how-attackers-can-exploit-forticlient-to-compromise-organizations-1-3/;
classtype:misc-activity;
sid:2066504; rev:1;
metadata:affected_product FortiClient_EMS, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2025_12_30, deployment Perimeter, deployment SSLDecrypt, confidence High, signature_severity Informational, updated_at 2025_12_30;
target:dest_ip;
)