alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE NSIS/TrojanDownloader.Agent.NZK CnC Activity M1"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/ntuser.txt"; bsize:11; fast_pattern; http.user_agent; content:"NSIS|5f|Inetc|20 28|Mozilla|29|"; bsize:20; reference:md5,168feb87d7264b4ee2b39cffd7d3b5e3; classtype:command-and-control; sid:2033990; 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, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_09_21;)