ET POLICY IRC Channel JOIN on non-standard port

Query · suricata

flow:established,to_server;
dsize:<64;
content:"JOIN "; nocase; depth:5;
pcre:"/&|#|\+|!/R";
target:src_ip;
Raw source ET POLICY IRC Channel JOIN on non-standard port · 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 $HOME_NET any -> $EXTERNAL_NET ![25,587,6666:7000,8076] (
    msg:"ET POLICY IRC Channel JOIN on non-standard port";
    flow:established,to_server;
    dsize:<64;
    content:"JOIN "; nocase; depth:5;
    pcre:"/&|#|\+|!/R";
    reference:url,www.rfc-editor.org/rfc/rfc1459#section-4.2.1;
    classtype:unusual-client-port-connection;
    sid:2000348; rev:18;
    metadata:attack_target Client_and_Server, created_at 2010_07_30, deployment Perimeter, performance_impact Moderate, confidence Medium, signature_severity Informational, updated_at 2023_05_09, reviewed_at 2024_09_16;
    target:src_ip;
)

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