ET ATTACK_RESPONSE Probably Evil Long Unicode string only string and unescape 2

Query · suricata

flow:established,from_server;
file_data;
content:"unescape";
content:"|27|%u"; nocase;
content:!"|27|"; within:120;
pcre:"/^[a-f0-9]{4}([\%\\]u[a-f0-9]{4}){20}/Ri";
Raw source ET ATTACK_RESPONSE Probably Evil Long Unicode string only string and unescape 2 · Suricata
Esc
Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET ATTACK_RESPONSE Probably Evil Long Unicode string only string and unescape 2";
    flow:established,from_server;
    file_data;
    content:"unescape";
    content:"|27|%u"; nocase;
    content:!"|27|"; within:120;
    pcre:"/^[a-f0-9]{4}([\%\\]u[a-f0-9]{4}){20}/Ri";
    classtype:bad-unknown;
    sid:2017500; rev:3;
    metadata:created_at 2013_09_20, deployment alert_only, signature_severity Minor, updated_at 2023_04_19;
)

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