alert tcp-pkt $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE W32.DarkVNC Variant Checkin"; flow:established,to_server; dsize:13; content:"|4a 01 4f 97 00|"; startswith; fast_pattern; reference:url,isc.sans.edu/diary/rss/28884; reference:url,www.malware-traffic-analysis.net/2022/07/26/index.html; classtype:command-and-control; sid:2037841; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_07_28, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, updated_at 2022_07_28;)