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Description

Detects messages from senders impersonating Mailchimp through display name spoofing or brand logo usage, combined with security-themed content and suspicious authentication patterns.

References

No references.

Sublime Security
Created May 5th, 2025 • Last updated Sep 22nd, 2025
Source
type.inbound
and (
  // display name contains Mailchimp
  (
    strings.ilike(strings.replace_confusables(sender.display_name),
                  '*mailchimp*'
    )
    // levenshtein distance similar to Mailchimp
    or strings.ilevenshtein(strings.replace_confusables(sender.display_name),
                            'mailchimp'
    ) <= 1
    or any(ml.logo_detect(file.message_screenshot()).brands,
           .name == "Mailchimp" and .confidence == "high"
    )
  )
)
and (
  any(beta.ml_topic(body.current_thread.text).topics,
      .name in (
        "Security and Authentication",
        "Secure Message",
        "Reminders and Notifications"
      )
      and .confidence in ("medium", "high")
  )
  or any(beta.ml_topic(beta.ocr(file.message_screenshot()).text).topics,
         .name in (
           "Security and Authentication",
           "Secure Message",
           "Reminders and Notifications"
         )
         and .confidence in ("medium", "high")
         and beta.ocr(file.message_screenshot()).text != ""
  )
  or any(ml.nlu_classifier(body.current_thread.text).intents,
         .name == "cred_theft" and .confidence == "high"
  )
  or any(ml.nlu_classifier(beta.ocr(file.message_screenshot()).text).intents,
         .name == "cred_theft" and .confidence == "high"
  )
)

// and the sender is not in org_domains or from Mailchimp domains and passes auth
and not (
  sender.email.domain.root_domain in $org_domains
  or (
    sender.email.domain.root_domain in ("intuit.com", "mailchimp.com")
    and headers.auth_summary.dmarc.pass
  )
)
and not strings.ends_with(headers.message_id, ".mailchimp.com>")
// and the sender is not from high trust sender root domains
and (
  (
    sender.email.domain.root_domain in $high_trust_sender_root_domains
    and not headers.auth_summary.dmarc.pass
  )
  or sender.email.domain.root_domain not in $high_trust_sender_root_domains
)
and not profile.by_sender().solicited
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