ET HUNTING HTTP Response Containing Base64-Encoded Powershell Payload Keywords

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET HUNTING HTTP Response Containing Base64-Encoded Powershell Payload Keywords";
    flow:established,to_client;
    http.stat_code;
    content:"200";
    http.response_body;
    content:"new-object"; nocase;
    content:"io.memorystream"; nocase; distance:0;
    content:"frombase64string"; fast_pattern; distance:0; nocase;
    content:"iex"; distance:0; nocase;
    reference:url,www.huntress.com/blog/malware-deep-dive-examining-a-powershell-payload;
    classtype:trojan-activity;
    sid:2062888; rev:1;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Windows_11, attack_target Client_and_Server, tls_state plaintext, created_at 2025_06_11, deployment Perimeter, performance_impact Low, confidence Medium, signature_severity Major, updated_at 2025_06_11, mitre_tactic_id TA0002, mitre_tactic_name Execution, mitre_technique_id T1059, mitre_technique_name Command_And_Scripting_Interpreter;
)