Brand impersonation: Square

name: "Brand impersonation: Square"
description: "Impersonation of Square, typically containing security-related language, secure message notifications, or credential theft indicators from unauthorized senders."
type: "rule"
severity: "medium"
source: |
  type.inbound
  and (
    // levenshtein distance similar to Square
    (
      strings.ilevenshtein(strings.replace_confusables(sender.display_name),
                           'square'
      ) <= 1
      and sender.display_name not in ("SquareX")
    )
    or any(ml.logo_detect(file.message_screenshot()).brands,
           .name == "Square" and .confidence == "high"
    )
  )
  and (
    (
      any(ml.nlu_classifier(body.current_thread.text).topics,
          .name in (
            "Security and Authentication",
            "Secure Message",
            "Reminders and Notifications"
          )
          and .confidence in ("medium", "high")
      )
      and not any(ml.nlu_classifier(body.current_thread.text).topics,
                  .name in ("Newsletters and Digests", "Entertainment and Sports")
                  and .confidence in ("medium", "high")
      )
    )
    or (
      any(ml.nlu_classifier(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 != ""
      )
      and not any(ml.nlu_classifier(beta.ocr(file.message_screenshot()).text).topics,
                  .name in ("Newsletters and Digests", "Entertainment and Sports")
                  and .confidence in ("medium", "high")
      )
    )
    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 Square domains and passes auth
  and not (
    sender.email.domain.root_domain in $org_domains
    or (
      sender.email.domain.root_domain in (
        "square.com",
        "squareup.com",
        "block.com"
      )
      and headers.auth_summary.dmarc.pass
    )
  )
  // 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
    or not headers.auth_summary.dmarc.pass
    or not headers.auth_summary.spf.pass
  )

attack_types:
  - "Credential Phishing"
tactics_and_techniques:
  - "Impersonation: Brand"
  - "Social engineering"
detection_methods:
  - "Computer Vision"
  - "Content analysis"
  - "Header analysis"
  - "Natural Language Understanding"
  - "Optical Character Recognition"
  - "Sender analysis"
id: "63f9b449-b2f3-50be-a284-5448b8f75ebf"