alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE NimPlant Register Activity (GET)"; flow:established,to_server; urilen:9; flowbits:set,ET.nimplant; flowbits:noalert; http.method; content:"GET"; http.uri; content:"/register"; fast_pattern; http.header_names; content:!"Referer"; reference:url,github.com/chvancooten/NimPlant; classtype:trojan-activity; sid:2044347; rev:1; metadata:attack_target Client_Endpoint, created_at 2023_02_27, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_02_27; target:src_ip;)