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Description

This rule flags messages with QR codes in attachments when there are three or fewer attachments. If no attachments are present, the rule captures a screenshot of the message for analysis. Additional triggers include: sender's name containing the recipient's SLD, recipient's email mentioned in the body, an empty message body, a suspicious subject, or undisclosed recipients.

References

No references.

Sublime Security
Created Oct 5th, 2023 • Last updated Dec 12th, 2025
Source
type.inbound
and (
  (
    length(attachments) <= 3
    or (
      any(attachments, length(ml.logo_detect(.).brands) > 0)
      and length(attachments) <= 10
    )
  )
  and (
    any(attachments,
        (
          .file_type in $file_types_images
          or .file_extension in $file_extensions_macros
          or .file_type == "pdf"
        )
        and (
          any(file.explode(.),
              (
                .scan.qr.type is not null
                and regex.contains(.scan.qr.data, '\.')
                and not strings.starts_with(.scan.qr.data,
                                            "https://qr.skyqr.co.za/"
                )
                and not (
                  strings.icontains(.scan.qr.data, ',')
                  and .scan.qr.type == 'undefined'
                )
                // not a json string
                and not (
                  strings.starts_with(.scan.qr.data, '{')
                  and strings.ends_with(.scan.qr.data, '}')
                )
                // exclude images taken with mobile cameras and screenshots from android
                and not any(.scan.exiftool.fields,
                            .key == "Model"
                            or (
                              .key == "Software"
                              and strings.starts_with(.value, "Android")
                            )
                )
                // exclude images taken with mobile cameras and screenshots from Apple
                and not any(.scan.exiftool.fields,
                            .key == "DeviceManufacturer"
                            and .value == "Apple Computer Inc."
                )
                // exclude images from WhatsApp (mobile)
                and not regex.match(.file_name,
                                    'WhatsApp Image \d\d\d\d-\d\d-\d\d at.*.jpe?g'
                )
                and not (
                  (
                    .scan.exiftool.image_height > 3000
                    and .scan.exiftool.image_height is not null
                  )
                  or (
                    .scan.exiftool.image_width > 3000
                    and .scan.exiftool.image_width is not null
                  )
                )
                // exclude contact cards
                and not strings.istarts_with(.scan.qr.data, "BEGIN:VCARD")

                // negate QR codes to legit Servicio de Administración Tributaria (SAT) Gov links
                and not (
                  .scan.qr.url.domain.root_domain is not null
                  and .scan.qr.url.domain.root_domain in ('sat.gob.mx')
                )
                and not (
                  .scan.qr.data is not null
                  and strings.icontains(.scan.qr.data, 'sat.gob.mx')
                )
              )
              or (
                regex.icontains(.scan.ocr.raw, 'scan|camera')
                and regex.icontains(.scan.ocr.raw, '\bQR\b|Q\.R\.|barcode')
              )
          )
        )
    )
    or (
      length(attachments) == 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 (
        (
          beta.parse_exif(file.message_screenshot()).image_height < 2000
          and beta.parse_exif(file.message_screenshot()).image_width < 2000
        )
        // ignore image height/width if there is excessive whitespace padding
        or regex.contains(body.html.raw,
                          '\"padding:0px 0px \d{3,4}px 0px'
        )
      )
      and any(beta.scan_qr(file.message_screenshot()).items,
              .type is not null
              and regex.contains(.data, '\.')
              // exclude contact cards
              and not strings.istarts_with(.data, "BEGIN:VCARD")
      )
    )
  )
  and (
    any(recipients.to,
        strings.icontains(sender.display_name, .email.domain.sld)
    )
    or length(body.current_thread.text) is null
    or (
      body.current_thread.text == ""
      and (
        (
          (length(headers.references) > 0 or headers.in_reply_to is null)
          and not (
            (
              strings.istarts_with(subject.subject, "RE:")
              or strings.istarts_with(subject.subject, "RES:")
              or strings.istarts_with(subject.subject, "R:")
              or strings.istarts_with(subject.subject, "ODG:")
              or strings.istarts_with(subject.subject, "答复:")
              or strings.istarts_with(subject.subject, "AW:")
              or strings.istarts_with(subject.subject, "TR:")
              or strings.istarts_with(subject.subject, "FWD:")
              or regex.imatch(subject.subject,
                              '(\[[^\]]+\]\s?){0,3}(re|fwd?|automat.*)\s?:.*'
              )
            )
          )
        )
        or length(headers.references) == 0
      )
    )
    or regex.contains(subject.subject,
                      "(Authenticat(e|or|ion)|2fa|Multi.Factor|(qr|bar).code|action.require|alert|Att(n|ention):)"
    )
    or (any(recipients.to, strings.icontains(subject.subject, .display_name)))
    or (
      regex.icontains(subject.subject,
                      "termination.*notice",
                      "38417",
                      ":completed",
                      "[il1]{2}mit.*ma[il1]{2} ?bo?x",
                      "[il][il][il]egai[ -]",
                      "[li][li][li]ega[li] attempt",
                      "[ng]-?[io]n .*block",
                      "[ng]-?[io]n .*cancel",
                      "[ng]-?[io]n .*deactiv",
                      "[ng]-?[io]n .*disabl",
                      "action.*required",
                      "abandon.*package",
                      "about.your.account",
                      "acc(ou)?n?t (is )?on ho[li]d",
                      "acc(ou)?n?t.*terminat",
                      "acc(oun)?t.*[il1]{2}mitation",
                      "access.*limitation",
                      "account (will be )?block",
                      "account.*de-?activat",
                      "account.*locked",
                      "account.*re-verification",
                      "account.*security",
                      "account.*suspension",
                      "account.has.been",
                      "account.has.expired",
                      "account.will.be.blocked",
                      "account v[il]o[li]at",
                      "activity.*acc(oun)?t",
                      "almost.full",
                      "app[li]e.[il]d",
                      "authenticate.*account",
                      "been.*suspend",
                      "bonus",
                      "clos.*of.*account.*processed",
                      "confirm.your.account",
                      "courier.*able",
                      "crediential.*notif",
                      "deactivation.*in.*progress",
                      "delivery.*attempt.*failed",
                      "document.received",
                      "documented.*shared.*with.*you",
                      "dropbox.*document",
                      "e-?ma[il1]+ .{010}suspen",
                      "e-?ma[il1]{1} user",
                      "e-?ma[il1]{2} acc",
                      "e-?ma[il1]{2}.*up.?grade",
                      "e.?ma[il1]{2}.*server",
                      "e.?ma[il1]{2}.*suspend",
                      "email.update",
                      "faxed you",
                      "fraud(ulent)?.*charge",
                      "from.helpdesk",
                      "fu[il1]{2}.*ma[il1]+[ -]?box",
                      "has.been.*suspended",
                      "has.been.limited",
                      "have.locked",
                      "he[li]p ?desk upgrade",
                      "heipdesk",
                      "i[il]iega[il]",
                      "ii[il]ega[il]",
                      "incoming e?mail",
                      "incoming.*fax",
                      "lock.*security",
                      "ma[il1]{1}[ -]?box.*quo",
                      "ma[il1]{2}[ -]?box.*fu[il1]",
                      "ma[il1]{2}box.*[il1]{2}mit",
                      "ma[il1]{2}box stor",
                      "mail on.?hold",
                      "mail.*box.*migration",
                      "mail.*de-?activat",
                      "mail.update.required",
                      "mails.*pending",
                      "messages.*pending",
                      "missed.*shipping.*notification",
                      "missed.shipment.notification",
                      "must.update.your.account",
                      "new [sl][io]g?[nig][ -]?in from",
                      "new voice ?-?mail",
                      "notifications.*pending",
                      "office.*3.*6.*5.*suspend",
                      "office365",
                      "on google docs with you",
                      "online doc",
                      "password.*compromised",
                      "payment advice",
                      "periodic maintenance",
                      "potential(ly)? unauthorized",
                      "refund not approved",
                      "report",
                      "revised.*policy",
                      "scam",
                      "scanned.?invoice",
                      "secured?.update",
                      "security breach",
                      "securlty",
                      "seguranca",
                      "signed.*delivery",
                      "status of your .{314}? ?delivery",
                      "susp[il1]+c[il1]+ous.*act[il1]+v[il1]+ty",
                      "suspicious.*sign.*[io]n",
                      "suspicious.activit",
                      "temporar(il)?y deactivate",
                      "temporar[il1]{2}y disab[li]ed",
                      "temporarily.*lock",
                      "un-?usua[li].activity",
                      "unable.*deliver",
                      "unauthorized.*activit",
                      "unauthorized.device",
                      "undelivered message",
                      "unread.*doc",
                      "unusual.activity",
                      "upgrade.*account",
                      "upgrade.notice",
                      "urgent message",
                      "urgent.verification",
                      "v[il1]o[li1]at[il1]on security",
                      "va[il1]{1}date.*ma[il1]{2}[ -]?box",
                      "verification ?-?require",
                      "verification( )?-?need",
                      "verify.your?.account",
                      "web ?-?ma[il1]{2}",
                      "web[ -]?ma[il1]{2}",
                      "will.be.suspended",
                      "your (customer )?account .as",
                      "your.office.365",
                      "your.online.access"
      )
      or any($suspicious_subjects, strings.icontains(subject.subject, .))
      or regex.icontains(sender.display_name,
                         "Accounts.?Payable",
                         "Admin",
                         "Administrator",
                         "Alert",
                         "Assistant",
                         "Billing",
                         "Benefits",
                         "Bonus",
                         "CEO",
                         "CFO",
                         "CIO",
                         "CTO",
                         "Chairman",
                         "Claim",
                         "Confirm",
                         "Critical",
                         "Customer Service",
                         "Deal",
                         "Discount",
                         "Director",
                         "Exclusive",
                         "Executive",
                         "Fax",
                         "Free",
                         "Gift",
                         "/bHR/b",
                         "Helpdesk",
                         "Human Resources",
                         "Immediate",
                         "Important",
                         "Info",
                         "Information",
                         "Invoice",
                         '\bIT\b',
                         "Legal",
                         "Lottery",
                         "Management",
                         "Manager",
                         "Member Services",
                         "Notification",
                         "Offer",
                         "Operations",
                         "Order",
                         "Partner",
                         "Payment",
                         "Payroll",
                         "President",
                         "Premium",
                         "Prize",
                         "Receipt",
                         "Refund",
                         "Registrar",
                         "Required",
                         "Reward",
                         "Sales",
                         "Secretary",
                         "Security",
                         "Service",
                         "Signature",
                         "Storage",
                         "Support",
                         "Sweepstakes",
                         "System",
                         "Tax",
                         "Tech Support",
                         "Update",
                         "Upgrade",
                         "Urgent",
                         "Validate",
                         "Verify",
                         "VIP",
                         "Webmaster",
                         "Winner",
      )
    )
    or (
      (
        length(recipients.to) == 0
        or all(recipients.to, .display_name == "Undisclosed recipients")
      )
      and length(recipients.cc) == 0
      and length(recipients.bcc) == 0
    )
    or any(beta.scan_qr(file.message_screenshot()).items,
           (
             .url.domain.tld in $suspicious_tlds
             and .url.domain.root_domain != "app.link"
           )
           // linkanalysis phishing disposition
           or ml.link_analysis(.url).credphish.disposition == "phishing"
    )
    or any(attachments,
           (
             .file_type in $file_types_images
             or .file_extension in $file_extensions_macros
             or .file_type == "pdf"
           )
           and any(file.explode(.),
                   (
                     .scan.qr.url.domain.tld in $suspicious_tlds
                     and .scan.qr.url.domain.root_domain != "app.link"
                     and .scan.qr.url.domain.root_domain != "qr.link"
                     and .scan.qr.url.domain.root_domain != "skyqr.co.za"
                   )
                   and .scan.qr.url.domain.root_domain not in $org_domains
           )
    )
    or sender.email.domain.tld in $suspicious_tlds
  )
)

// sender profile is new or outlier
and (
  profile.by_sender_email().any_messages_malicious_or_spam
  or (
    sender.email.domain.domain in $org_domains
    and not coalesce(headers.auth_summary.dmarc.pass, false)
  )
  or (
    profile.by_sender_email().prevalence in ("new", "outlier")
    and not profile.by_sender_email().solicited
  )
)
and not profile.by_sender_email().any_messages_benign
// negate highly trusted sender domains unless they fail DMARC authentication
and not (
  sender.email.domain.root_domain in $high_trust_sender_root_domains
  and coalesce(headers.auth_summary.dmarc.pass, false)
)
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