alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Backdoor.Elise CnC Beacon 2"; flow:to_server,established; http.method; content:"POST"; http.uri; content:".html"; nocase; fast_pattern; pcre:"/\/\d{8,10}\.html$/i"; http.content_len; byte_test:0,=,0,0,string,dec; http.host; content:!"www.youdao.com"; startswith; http.header_names; content:!"Content-Type|0d 0a|"; content:!"Accept-"; content:!"Referer|0d 0a|"; reference:md5,cfa7954722d4277d26e96edc3289a4ce; reference:url,github.com/pan-unit42/iocs/tree/master/lotusblossom; classtype:command-and-control; sid:2021276; rev:7; metadata:attack_target Client_Endpoint, created_at 2015_06_16, deployment Perimeter, performance_impact Significant, signature_severity Major, tag c2, updated_at 2024_04_29, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)