• Sublime Core Feed

Description

Detects spam emails where the 'To' and 'CC' fields match, using indicators such as short body length with spam keywords, unsolicited content, dmarc failures, fake threads, and suspicious links.

References

No references.

Sublime Security
Created May 24th, 2024 • Last updated Jan 12th, 2026
Source
type.inbound

// one recipient and 1 cc
and length(recipients.to) == 1
and length(recipients.cc) == 1

// unsolicited
and not profile.by_sender().solicited

// recipients email matches the cc email
and any(recipients.to, any(recipients.cc, .email.email == ..email.email))

// body is short with spam keywords
and (
  (
    length(body.current_thread.text) < 150
    and strings.ilike(body.current_thread.text,
                      "*congrat*",
                      "*win*",
                      "*expired*",
                      "*subscription*",
                      "*won*",
                      "*gift*",
                      "*CARTE CADEAU*",
                      "*Votre chance*",
                      "*survey*",
                      "*livraison*",
                      "*delivery*",
                      "*package*"
    )
  )

  // body is super short
  or length(body.current_thread.text) < 10

  // body has no spaces
  or regex.imatch(body.current_thread.text, '[^ ]+')

  // subject is null
  or subject.subject == ""

  // dmarc failure
  or not headers.auth_summary.dmarc.pass

  // or display text contains suspicious terms
  or any(body.links,
         regex.icontains(.display_text,
                         'Congrat|Survey|package|delivery|\bclaim\b'
         )
         and not .href_url.domain.root_domain == "surveymonkey.com"
  )

  // compauth failure
  or any(headers.hops,
         .authentication_results.compauth.verdict not in (
           "pass",
           "softpass",
           "none"
         )
  )

  // all links display text is null or aka.ms
  or (
    length(filter(body.links,
                  (
                    (
                      .display_text is null
                      and .href_url.domain.root_domain != sender.email.domain.root_domain
                    )
                    or .href_url.domain.root_domain in (
                      "aka.ms",
                      "mimecast.com",
                      "mimecastprotect.com",
                      "cisco.com"
                    )
                  )
           )
    ) == length(body.links)
  )
  or (
    // fake thread check
    regex.imatch(subject.subject, '(\[[^\]]+\]\s?){0,3}(re|fwd?)\s?:.*')
    and (
      (length(headers.references) == 0 and headers.in_reply_to is null)
      or not any(headers.hops,
                 any(.fields, strings.ilike(.name, "In-Reply-To"))
      )
    )
  )
)
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