alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/ObserverStealer CnC Activity M2 (Check-in)"; flow:established,to_server; urilen:1; http.method; content:"POST"; http.user_agent; content:"HTTP/1.1"; bsize:8; fast_pattern; http.header; content:"|3a 20|HWID|0d 0a|"; http.request_body; pcre:"/^\x7b[0-9a-f]{8}-(?:([0-9a-f]{4}-){3})[0-9a-f]{12}\x7d$/"; http.header_names; content:!"Referer"; reference:md5,4a650883227d0f88b5e6b7c48a456939; classtype:trojan-activity; sid:2051447; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Windows_11, attack_target Client_Endpoint, tls_state plaintext, created_at 2024_03_04, deployment Perimeter, malware_family ObserverStealer, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_03_04, mitre_tactic_id TA0009, mitre_tactic_name Collection, mitre_technique_id T1005, mitre_technique_name Data_from_local_system; target:src_ip;)