Sublime Security medium experimental mql

Business Email Compromise (BEC) attempt from unsolicited sender

Detects potential Business Email Compromise (BEC) attacks by analyzing text within the email body from unsolicited senders.

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Detection Logic

type.inbound
and any(ml.nlu_classifier(body.current_thread.text).intents,
        .name in ("bec") and .confidence == "high"
)
and 
// mismatched From and Reply-to
(
  (
    length(headers.reply_to) > 0
    and all(headers.reply_to,
            .email.domain.root_domain != sender.email.domain.root_domain
    )
  )
  or not headers.auth_summary.dmarc.pass
  or not headers.auth_summary.spf.pass
)

// negate "via" senders via dmarc authentication or gmail autoforwards
and not (
  strings.ilike(headers.return_path.local_part, "*+caf_=*")
  and strings.contains(sender.display_name, "via")
  and (headers.auth_summary.dmarc.pass)
)
and (
  not profile.by_sender().solicited
  or (
    profile.by_sender().any_messages_malicious_or_spam
    and not profile.by_sender().any_messages_benign
  )
)

Field Validations

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