alert tcp $HOME_NET any -> $EXTERNAL_NET 1024: (msg:"ET MALWARE Win32/Kryptik.GSKY CnC Checkin"; flow:established,to_server; stream_size:server,<,5; content:"|45 36 27 18|"; startswith; fast_pattern; content:"|23|"; distance:0; content:"Api"; distance:0; reference:md5,0d6118f766b0d75a5085bced64793d76; classtype:command-and-control; sid:2037822; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_07_25, deployment Perimeter, malware_family Win32_Kryptik_GSKY, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_10_17;)