ET MALWARE PowerShell Downloader CnC Activity

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE PowerShell Downloader CnC Activity";
    flow:established,to_server;
    http.method;
    content:"POST";
    http.user_agent;
    content:".NET|20|";
    content:"E9PQ"; distance:2; within:4; fast_pattern;
    content:!"|20|"; distance:0;
    http.header_names;
    content:!"|0d 0a|Referer|0d 0a|";
    classtype:command-and-control;
    sid:2030151; rev:2;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_05_11, deployment Perimeter, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_05_11;
)