alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE ArcDoor Intial Checkin"; flow:established,to_server; urilen:1; http.method; content:"POST"; http.header; header_lowercase; content:"content-length|3a 20|28|0d 0a|"; fast_pattern; http.request_body; pcre:"/^[a-z0-9]{11}=\d{16}$/"; http.header_names; to_lowercase; content:!"|0d 0a|accept"; reference:md5,71bae4762a6d2c446584f1ae991a8fbe; classtype:command-and-control; sid:2020345; rev:6; metadata:created_at 2015_02_03, signature_severity Major, updated_at 2024_04_21;)