alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE APT-C-23 Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.cookie; content:"btst="; startswith; fast_pattern; pcre:"/\|\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\|/"; http.header_names; content:"|0d 0a|User-Agent|0d 0a|Host|0d 0a|Connection|0d 0a|Cookie|0d 0a 0d 0a|"; content:!"Referer"; reference:md5,f9854aa5bc138498a12af8a45f89dd84; classtype:trojan-activity; sid:2033198; rev:3; metadata:attack_target Client_Endpoint, created_at 2021_06_25, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_07_15;)