alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Cloud Atlas CnC Beacon"; flow:established,to_server; urilen:10; threshold:type limit, count 1, seconds 120, track by_src; http.method; content:"POST"; http.uri; content:"/check.jsp"; fast_pattern; http.content_type; content:"application/octet-stream"; bsize:24; http.header_names; content:!"Referer|0d 0a|"; reference:url,securelist.com/blog/research/68083/cloud-atlas-redoctober-apt-is-back-in-style/; classtype:command-and-control; sid:2019919; rev:4; metadata:attack_target Client_Endpoint, created_at 2014_12_11, deployment Perimeter, signature_severity Major, tag c2, updated_at 2020_09_28, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)