alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Backdoor.Elise CnC Beacon 1 M2"; flow:to_server,established; content:"Cookie|3a 20|A="; fast_pattern; http.method; content:"GET"; http.uri; content:"/"; offset:9; depth:1; content:".html"; nocase; endswith; pcre:"/^\/[a-f0-9]{8}\/\D+\d{8,10}\.html$/i"; http.header_names; content:!"Accept-"; content:!"Referer|0d 0a|"; reference:md5,23ace716ec34bfd9c98efd79b23a01af; reference:url,github.com/pan-unit42/iocs/tree/master/lotusblossom; classtype:command-and-control; sid:2021275; rev:9; metadata:attack_target Client_Endpoint, created_at 2015_06_16, deployment Perimeter, signature_severity Major, tag c2, updated_at 2022_03_24, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)