alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Voltron/Spectre Stealer Checkin Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/v4/api_t.php?id="; startswith; fast_pattern; http.user_agent; content:"UserAgent"; bsize:9; http.header_names; content:!"Referer"; classtype:trojan-activity; sid:2034038; rev:1; metadata:attack_target Client_Endpoint, created_at 2021_09_17, deployment Perimeter, malware_family Win32_Voltron_Spectre, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_09_17;)