alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Small.NMZ CnC Checkin"; flow:established,to_server; http.request_line; content:"GET|20|/O.htm|20|"; fast_pattern; http.user_agent; content:"|3b 2b|SV1|3b|"; http.header_names; content:"|0d 0a|Cache-Control|0d 0a|Connection|0d 0a|Pragma|0d 0a|User-Agent|0d 0a|Host|0d 0a 0d 0a|"; startswith; reference:md5,4a8af3635882ee62d67ec9dd47c87796; classtype:command-and-control; sid:2037879; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_08_01, deployment Perimeter, malware_family Win32_Small_NMZ, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_08_01, reviewed_at 2024_12_24;)