ET HUNTING Possible Covid19 Themed Email Spam Outbound M4

Query · suricata

flow:to_server,established;
content:"corona virus"; nocase; fast_pattern;
threshold:type threshold, count 5, seconds 120, track by_src;
Raw source ET HUNTING Possible Covid19 Themed Email Spam Outbound M4 · Suricata
Esc
Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert smtp $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET HUNTING Possible Covid19 Themed Email Spam Outbound M4";
    flow:to_server,established;
    content:"corona virus"; nocase; fast_pattern;
    threshold:type threshold, count 5, seconds 120, track by_src;
    classtype:bad-unknown;
    sid:2029779; rev:2;
    metadata:created_at 2020_03_31, confidence Medium, signature_severity Minor, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_03_31;
)

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