sublimemediumRule

Credential phishing: Tax form impersonation with payment request

Detects messages impersonating tax-related communications that contain payment requests and PDF links, excluding legitimate tax service providers. The rule identifies tax terminology combined with payment solicitation language and PDF link references, which is a common pattern in tax season scams.

MITRE ATT&CK

T1566.002 T1534 T1656 T1566 T1566.001 T1598 T1598.003

initial-access

Detection Query

type.inbound
and any([body.current_thread.text, subject.subject],
        regex.icontains(.,
                        'schedule.c\b',
                        'tax.form',
                        '1099\b',
                        '\bw-?2\b',
                        'tax.return',
                        'tax.preparation'
        )
        and (
          regex.icontains(body.current_thread.text,
                          "reply.with.your.payment",
                          "payment.details",
                          "send.payment.information",
                          "provide.payment",
                          "payment.method",
                          "billing.information",
                          "processing.fee",
                          "completion.fee"
          )
        )
        and any(body.links, strings.icontains(.display_text, "PDF"))
)
and not any(ml.nlu_classifier(body.current_thread.text).topics,
            .name in ("Events and Webinars", "Newsletters and Digests")
)
and not sender.email.domain.root_domain in (
  "intuit.com",
  "hrblock.com",
  "turbotax.com",
  "taxact.com",
  "freetaxusa.com",
  "geico.com",
  "eventshq.com",
  "square.com"
)
// 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
)

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

Raw Content

name: "Credential phishing: Tax form impersonation with payment request"
description: "Detects messages impersonating tax-related communications that contain payment requests and PDF links, excluding legitimate tax service providers. The rule identifies tax terminology combined with payment solicitation language and PDF link references, which is a common pattern in tax season scams."
type: "rule"
severity: "medium"
source: |
  type.inbound
  and any([body.current_thread.text, subject.subject],
          regex.icontains(.,
                          'schedule.c\b',
                          'tax.form',
                          '1099\b',
                          '\bw-?2\b',
                          'tax.return',
                          'tax.preparation'
          )
          and (
            regex.icontains(body.current_thread.text,
                            "reply.with.your.payment",
                            "payment.details",
                            "send.payment.information",
                            "provide.payment",
                            "payment.method",
                            "billing.information",
                            "processing.fee",
                            "completion.fee"
            )
          )
          and any(body.links, strings.icontains(.display_text, "PDF"))
  )
  and not any(ml.nlu_classifier(body.current_thread.text).topics,
              .name in ("Events and Webinars", "Newsletters and Digests")
  )
  and not sender.email.domain.root_domain in (
    "intuit.com",
    "hrblock.com",
    "turbotax.com",
    "taxact.com",
    "freetaxusa.com",
    "geico.com",
    "eventshq.com",
    "square.com"
  )
  // 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
  )

attack_types:
  - "BEC/Fraud"
  - "Credential Phishing"
tactics_and_techniques:
  - "Impersonation: Brand"
  - "Social engineering"
  - "PDF"
detection_methods:
  - "Content analysis"
  - "Header analysis"
  - "Sender analysis"
  - "URL analysis"
id: "717695cf-caf0-5673-a8a8-223bb56ec8e1"