alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Final1stspy CnC Checkin (Reaper/APT37 Stage 1 Payload)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:".php?MachineId="; content:"&InfoSo="; distance:0; content:"&Index="; distance:0; content:"&Account="; distance:0; content:"&List="; distance:0; pcre:"/^(?:[A-Z0-9+/]{4})*(?:[A-Z0-9+/]{2}==|[A-Z0-9+/]{3}=|[A-Z0-9+/]{4})$/Ri"; http.user_agent; content:"Host|20|Process|20|Update"; fast_pattern; endswith; http.header_names; content:!"Referer"; reference:url,researchcenter.paloaltonetworks.com/2018/10/unit42-nokki-almost-ties-the-knot-with-dogcall-reaper-group-uses-new-malware-to-deploy-rat/; reference:md5,0f1d3ed85fee2acc23a8a26e0dc12e0f; reference:md5,a2fe5dcb08ae8b72e8bc98ddc0b918e7; classtype:targeted-activity; sid:2026431; rev:4; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2018_10_01, deployment Perimeter, malware_family Final1stspy, performance_impact Low, confidence High, signature_severity Major, tag APT37, tag ReaperGroup, updated_at 2020_09_16;)