Brand impersonation: Microsoft with embedded logo and credential theft language

name: "Brand impersonation: Microsoft with embedded logo and credential theft language"
description: "This rule detects messages impersonating Microsoft via a logo and contains credential theft language. From a new and unsolicited sender."
type: "rule"
severity: "high"
source: |
  type.inbound
  and (
    (
      length(attachments) > 0
      and all(attachments,
              .file_type in $file_types_images or .file_type == "pdf"
      )
    )
    or length(attachments) == 0
  )
  and any(ml.logo_detect(file.message_screenshot()).brands,
          strings.starts_with(.name, "Microsoft")
  )
  and (
    any(ml.nlu_classifier(body.current_thread.text).intents,
        .name == "cred_theft" and .confidence in ("medium", "high")
    )
    or (
      length(body.current_thread.text) == 0
      //
      // This rule makes use of a beta feature and is subject to change without notice
      // using the beta feature in custom rules is not suggested until it has been formally released
      //
      and any(ml.nlu_classifier(beta.ocr(file.message_screenshot()).text).intents,
              .name == "cred_theft" and .confidence in ("medium", "high")
      )
    )
  )
  and (
    not (
      headers.auth_summary.dmarc.pass
      and headers.auth_summary.dmarc.details.from.domain in (
        "azureadnotifications.us",
        "microsoft.com",
        "sharepointonline.com",
        "cloudappsecurity.com",
        "microsoftsupport.com",
        "microsoft.onmicrosoft.com",
        "yammer.com"
      )
    )
    or headers.auth_summary.dmarc.pass is null
    or headers.auth_summary.dmarc.details.from.domain is null
  )
  and not (
    sender.email.domain.domain == "planner.office365.com"
    and headers.return_path.email == "noreply@planner.office365.com"
    and headers.auth_summary.dmarc.details.from.root_domain == "office365.com"
  )
  // Microsoft has some legit onmicrosoft domains...
  and not (
    sender.email.domain.domain == "microsoft.onmicrosoft.com"
    and headers.auth_summary.spf.pass
    and all(body.links, .href_url.domain.root_domain == "microsoft.com")
  )
  // message is not from sharepoint actual (additional check in case DMARC check above fails to bail out)
  and not (
    (
      strings.ilike(headers.message_id,
                    '<Share-*',
                    '<MassDelete-*',
                    '<FileDeleteAfterExpiration-*',
                    '<NotifyOwnerSharedWithExternalUsers*',
                    '<OneTimePasscode*'
      )
      and strings.ends_with(headers.message_id, '@odspnotify>')
    )
    or (
      any(headers.hops,
          any(.fields,
              .name == "X-Google-Original-Message-ID"
              and strings.ilike(.value,
                                '<Share-*',
                                '<MassDelete-*',
                                '<FileDeleteAfterExpiration-*',
                                '<NotifyOwnerSharedWithExternalUsers*',
                                '<OneTimePasscode*'
              )
              and strings.ends_with(.value, '@odspnotify>')
          )
      )
    )
  )
  and (
    not profile.by_sender().solicited
    or (
      profile.by_sender().any_messages_malicious_or_spam
      and not profile.by_sender().any_messages_benign
    )
  )
  
  // negate org domains unless they fail DMARC authentication
  and (
    (
      sender.email.domain.root_domain in $org_domains
      and (
        not headers.auth_summary.dmarc.pass
        // MS quarantine digest emails from an org domain are router "internally" to MS, therefore, there is no authentication information
        or not (
          headers.auth_summary.dmarc.pass is null
          and all(headers.domains,
                  .root_domain in ("outlook.com", "office365.com")
          )
          // typical emails from freemail Outlook accounts are from prod.outlook.com
          and strings.ends_with(headers.message_id, "protection.outlook.com>")
        )
      )
    )
    or sender.email.domain.root_domain not in $org_domains
  )
  
  // negate highly trusted sender domains unless they fail DMARC authentication
  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().any_messages_benign

attack_types:
  - "Credential Phishing"
tactics_and_techniques:
  - "Impersonation: Brand"
  - "Social engineering"
detection_methods:
  - "Computer Vision"
  - "Natural Language Understanding"
  - "Sender analysis"
id: "3ee9ef3d-8ec4-5df0-a8a2-5c6d037eb17a"