alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE NSIS/TrojanDownloader.Agent.NZK Server Response"; flow:established,to_client; file.data; content:"|ce f8 f4 fc fb c8 98 9f|"; startswith; fast_pattern; content:"|98 9f|"; content:"|98 9f|"; endswith; reference:md5,168feb87d7264b4ee2b39cffd7d3b5e3; classtype:command-and-control; sid:2033992; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2021_09_21, deployment Perimeter, performance_impact Low, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_09_21;)