Display name and subject impersonation using recipient SLD (new sender)

type.inbound
and (
  // recipient SLD is being impersonated in the subject + display name
  (
    // these are usually targeted with just 1 recipient,
    // but sometimes they CC themselves or have a blank CC
    (
      length(recipients.to) + length(recipients.cc) + length(recipients.bcc) <= 2
    )
    and any(recipients.to,
            length(.email.domain.sld) >= 4
            // ensure that we're checking the org SLD
            and .email.domain.sld in $org_slds
            and strings.icontains(subject.subject, .email.domain.sld)
            and strings.icontains(sender.display_name, .email.domain.sld)
    )
  )
  or (
    // accounts for BCC'd messages where the recipients are empty
    // if BCC, sometimes the recipient will be the attacker's email
    (
      length(recipients.to) + length(recipients.cc) + length(recipients.bcc) <= 2
    )
    and length(mailbox.email.domain.sld) >= 4
    and strings.icontains(subject.subject, mailbox.email.domain.sld)
    and strings.icontains(sender.display_name, mailbox.email.domain.sld)
  )
)
and (
  // at least 1 link or non-image attachment
  (
    length(body.links) > 0
    // these attacks all use compromosed senders, so we look for a domain
    // that doesn't match the sender's domain to weed out legit messages
    and any(body.links,
            .href_url.domain.root_domain != sender.email.domain.root_domain
    )
  )
  or length(filter(attachments, .file_type not in $file_types_images)) > 0
)
and not (
  strings.contains(sender.display_name, "on behalf of")
  and sender.email.domain.root_domain == "microsoftonline.com"
)
and all(recipients.to, .email.email != sender.email.email)

// negate org domain senders, which can often be misconfigured and fail
// authentication, causing them to be type.inbound instead of type.internal.
// this is fine because we should catch spoofs in other ways.
// also, we use root_domain here to account for subdomains used by internal tools that aren't connected to the tenant.
// this should also be safe because domains like onmicrosoft[.]com are tracked as FQDNs in $org_domains, so they won't match
and 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().solicited
  or (
    profile.by_sender().any_messages_malicious_or_spam
    and not profile.by_sender().any_messages_benign
  )
)
and not profile.by_sender().any_messages_benign