alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE CountLoader CnC Checkin"; flow:established,to_server; flowbits:set,ET.CountLoader; http.method; content:"GET"; http.uri; content:"|2f|connect|3f|hwid|3d|"; fast_pattern; content:"&buildId="; distance:0; content:"&av="; distance:0; content:"&username="; distance:0; reference:url,silentpush.com/blog/countloader; reference:md5,8beece81a6dca4e5a8483f56917344ff; classtype:trojan-activity; sid:2072401; rev:1; metadata:affected_product Windows_Client, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2026_10_08, deployment Perimeter, deployment SSLDecrypt, malware_family CountLoader, confidence High, signature_severity Critical, updated_at 2026_10_08, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol; target:src_ip;)