ET HUNTING SUSPICIOUS SMTP EXE - RAR file with .exe filename inside

Query · suricata

flow:established;
content:"|0D 0A 0D 0A|UmFyI";
pcre:"/^[A-Za-z0-9\/\+\x0D\x0A]+?(5leG|LmV4|uZXhl)/R";
Raw source ET HUNTING SUSPICIOUS SMTP EXE - RAR file with .exe filename inside · Suricata
Esc
Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert smtp $EXTERNAL_NET any -> $SMTP_SERVERS any (
    msg:"ET HUNTING SUSPICIOUS SMTP EXE - RAR file with .exe filename inside";
    flow:established;
    content:"|0D 0A 0D 0A|UmFyI";
    pcre:"/^[A-Za-z0-9\/\+\x0D\x0A]+?(5leG|LmV4|uZXhl)/R";
    classtype:bad-unknown;
    sid:2017885; rev:5;
    metadata:created_at 2013_12_20, confidence Medium, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;
)

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