ET POLICY Outbound SMTP NTLM Authentication Observed

Query · suricata

flow:established,to_server;
content:"AUTH|20|ntlm|20|"; depth:10; nocase; fast_pattern;
pcre:"/^(?:[A-Z0-9+/]{4})*(?:[A-Z0-9+/]{2}==|[A-Z0-9+/]{3}=|[A-Z0-9+/]{4})$/Ri";
Raw source ET POLICY Outbound SMTP NTLM Authentication Observed · 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 -> $EXTERNAL_NET any (
    msg:"ET POLICY Outbound SMTP NTLM Authentication Observed";
    flow:established,to_server;
    content:"AUTH|20|ntlm|20|"; depth:10; nocase; fast_pattern;
    pcre:"/^(?:[A-Z0-9+/]{4})*(?:[A-Z0-9+/]{2}==|[A-Z0-9+/]{3}=|[A-Z0-9+/]{4})$/Ri";
    classtype:policy-violation;
    sid:2027152; rev:1;
    metadata:attack_target Client_and_Server, created_at 2019_04_04, deployment Perimeter, performance_impact Low, confidence High, signature_severity Minor, updated_at 2019_07_26;
)

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