ET INFO Possible SMTP Data Exfiltration - File Attachment Named Files.zip

Query · suricata

flow:established,to_server;
content:"Content-Type|3a 20|application/x-zip-compressed|3b 0d 0a|";
content:"name|3d 22|Files.zip|22 0d 0a|"; distance:0; fast_pattern;
content:"Content-Transfer-Encoding|3a 20|base64|0d 0a|"; distance:0;
content:"Content-Disposition|3a 20|attachment|3b 0d 0a|"; distance:0;
content:"filename|3d 22|Files.zip|22 0d 0a 0d 0a|"; distance:0;
Raw source ET INFO Possible SMTP Data Exfiltration - File Attachment Named Files.zip · 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 smtp $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET INFO Possible SMTP Data Exfiltration - File Attachment Named Files.zip";
    flow:established,to_server;
    content:"Content-Type|3a 20|application/x-zip-compressed|3b 0d 0a|";
    content:"name|3d 22|Files.zip|22 0d 0a|"; distance:0; fast_pattern;
    content:"Content-Transfer-Encoding|3a 20|base64|0d 0a|"; distance:0;
    content:"Content-Disposition|3a 20|attachment|3b 0d 0a|"; distance:0;
    content:"filename|3d 22|Files.zip|22 0d 0a 0d 0a|"; distance:0;
    reference:md5,1d9be2dfd54bf4a986c6cd1b7b630750;
    classtype:bad-unknown;
    sid:2044136; rev:1;
    metadata:affected_product Any, attack_target Client_Endpoint, created_at 2023_02_06, deployment Perimeter, performance_impact Low, confidence Low, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_02_06;
)

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