alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE CoreDn CnC Checkin M2"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/lib.asp?search="; fast_pattern; pcre:"/^[a-z0-9]{5,30}$/Ri"; http.accept; content:"*/*"; http.accept_enc; content:"gzip, deflate"; http.header_names; content:!"Referer"; content:!"Cache"; reference:url,blog.talosintelligence.com/2019/01/fake-korean-job-posting.html; classtype:command-and-control; sid:2026866; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_01_31, deployment Perimeter, malware_family CoreDn, performance_impact Low, confidence High, signature_severity Major, tag APT, updated_at 2020_08_27;)