ET HUNTING Suspicious Percentage Symbol Usage in FTP Username

Query · suricata

flow:established,to_server;
content:"USER "; depth:5; nocase;
content:!"|0d 0a|"; within:50;
content:"%"; distance:0;
Raw source ET HUNTING Suspicious Percentage Symbol Usage in FTP Username · Suricata
Esc
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 HUNTING Suspicious Percentage Symbol Usage in FTP Username";
    flow:established,to_server;
    content:"USER "; depth:5; nocase;
    content:!"|0d 0a|"; within:50;
    content:"%"; distance:0;
    reference:url,www.checkpoint.com/defense/advisories/public/2010/sbp-16-Aug.html;
    classtype:bad-unknown;
    sid:2011487; rev:2;
    metadata:created_at 2010_09_29, confidence Medium, signature_severity Informational, updated_at 2019_07_26;
)

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