alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Ursa Loader CnC Checkin"; flow:established,to_server; urilen:1; http.method; content:"POST"; http.user_agent; content:"Mozilla/3.0 (compatible|3b 20|Indy Library)"; fast_pattern; http.request_body; pcre:"/^[a-z]{1,10}=[A-Z]+(?:&[a-z]{1,10}=[A-Z]+){2,}$/s"; http.request_line; content:"POST / HTTP/1.0"; depth:15; endswith; http.content_type; content:"application/x-www-form-urlencoded"; http.header_names; content:!"Referer"; reference:md5,d05af060e3e104dea638f17c4bceb5ac; classtype:command-and-control; sid:2026756; rev:4; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2018_12_07, deployment Perimeter, malware_family Ursa_Loader, performance_impact Moderate, confidence Medium, signature_severity Major, updated_at 2020_09_16;)