Attachment: HTML Smuggling Microsoft Sign In

type.inbound
and any(attachments,
        (
          .file_extension in~ ("html", "htm", "shtml", "dhtml")
          or .file_extension in~ $file_extensions_common_archives
          or .file_type == "html"
        )
        and any(file.explode(.),
                .scan.entropy.entropy >= 5.7
                and .flavors.mime == "text/html"
                and length(.scan.javascript.identifiers) == 0
                and any(.scan.url.urls,
                        .domain.domain not in $tranco_1m
                        or .domain.root_domain in $free_subdomain_hosts
                )

                // seen in the wild: "sign in to your account", "sign in to your microsoft account"
                and strings.ilike(.scan.html.title, "*sign in*", "*microsoft*")
        )
)
and (
  not profile.by_sender().solicited
  or (
    profile.by_sender().any_messages_malicious_or_spam
    and not profile.by_sender().any_false_positives
  )
)
// allow Microsoft domains just to be safe
and sender.email.domain.root_domain not in~ ('microsoft.com', 'microsoftsupport.com', 'office.com')