ET SCAN Multiple FTP Administrator Login Attempts from Single Source - Possible Brute Force Attempt

Query · suricata

flow:established,to_server;
content:"USER "; nocase; depth:5;
content:"administrator"; within:25; nocase;
threshold:type threshold, track by_src, count 5, seconds 60;
Raw source ET SCAN Multiple FTP Administrator Login Attempts from Single Source - Possible Brute Force Attempt · Suricata
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Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert tcp $EXTERNAL_NET any -> $HOME_NET 21 (
    msg:"ET SCAN Multiple FTP Administrator Login Attempts from Single Source - Possible Brute Force Attempt";
    flow:established,to_server;
    content:"USER "; nocase; depth:5;
    content:"administrator"; within:25; nocase;
    threshold:type threshold, track by_src, count 5, seconds 60;
    classtype:attempted-recon;
    sid:2010643; rev:3;
    metadata:created_at 2010_07_30, confidence Medium, signature_severity Informational, updated_at 2019_07_26;
)

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