• Sublime Core Feed

Description

Email contains a Constant Contact (mass mailing platform) tracking link but does not originate from Constant Contact sending infrastructure. The rs6.net domain has been abused by threat actors to attempt credential phishing.

References

No references.

Sublime Security
Created Jan 22nd, 2024 • Last updated Oct 17th, 2025
Source
type.inbound
and (
  (
    length(body.links) < 15
    and any(body.links,
            .href_url.domain.root_domain in (
              "rs6.net",
              "constantcontactpages.com"
            )
    )
  )
  or (
    length(attachments) <= 3
    and (
      any(attachments,
          (.file_type in $file_types_images or .file_type == "pdf")
          //
          // 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(beta.scan_qr(.).items,
                  .type is not null
                  and .url.domain.root_domain in (
                    "rs6.net",
                    "constantcontactpages.com"
                  )
          )
          //
          // 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
          //
          // exclude images taken with mobile cameras and screenshots from android
          and not any(beta.parse_exif(.).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(beta.parse_exif(.).fields,
                      .key == "DeviceManufacturer"
                      and .value == "Apple Computer Inc."
          )
      )
      or (
        length(attachments) == 0
        and (
          //
          // 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
          //
          beta.parse_exif(file.message_screenshot()).image_height < 2000
          and beta.parse_exif(file.message_screenshot()).image_width < 2000
          and beta.scan_qr(file.message_screenshot()).found
          and any(beta.scan_qr(file.message_screenshot()).items,
                  .type is not null and .url.domain.root_domain == "rs6.net"
          )
        )
      )
    )
  )
)
and not (
  any(headers.hops,
      strings.icontains(.authentication_results.spf_details.designator,
                        "constantcontact.com"
      )
  )
  or any(headers.hops,
         strings.icontains(.received_spf.designator, "constantcontact.com")
  )
  or (
    (
      any(headers.hops,
          any(.authentication_results.dkim_details,
              .domain == "auth.ccsend.com"
          )
      )
    )
    and headers.auth_summary.dmarc.pass
  )
  or any(headers.references, strings.iends_with(., "ccsend.com"))
)
// negating legit replies
and not (
  (
    strings.istarts_with(subject.subject, "RE:")
    or strings.istarts_with(subject.subject, "FW:")
    or strings.istarts_with(subject.subject, "FWD:")
    or strings.istarts_with(subject.subject, "Automatic reply:")
    or regex.imatch(subject.subject,
                    '(\[[^\]]+\]\s?){0,3}(re|fwd?|automat.*)\s?:.*'
    )
  )
  and (
    length(headers.references) > 0
    or any(headers.hops, any(.fields, strings.ilike(.name, "In-Reply-To")))
  )
)
// 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 profile.by_sender().prevalence in ("new", "outlier", "rare")
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