Attachment: PDF with Microsoft Purview message impersonation

type.inbound
and any(filter(attachments, .file_extension == 'pdf'),
        any(ml.nlu_classifier(beta.ocr(.).text).topics,
            .name == 'Secure Message' and .confidence == 'high'
        )
        and strings.icontains(beta.ocr(.).text, "Microsoft Purview Message")
)
// 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
)