sublimelowRule

Service abuse: Evernote link

Detects inbound messages containing a link whose effective destination resolves to evernote.com, where the link text uses document-sharing or e-signature language (e.g., view, open, download, review) and the sender is not from evernote.com. The message body is also classified by an NLU model as exhibiting credential theft or business email compromise intent, indicating abuse of Evernote's legitimate hosting infrastructure to deliver malicious content.

MITRE ATT&CK

T1566 T1566.001 T1566.002 T1598 T1534 T1656

initial-access

Detection Query

type.inbound
// a link whose effective destination is evernote
and any(body.current_thread.links,
        (
          .href_url.domain.root_domain == "evernote.com"
          or .display_url.domain.root_domain == "evernote.com"
          or any(.href_url.query_params_decoded["domain"],
                 strings.iends_with(., "evernote.com")
          )
        )
        and (
          any(ml.nlu_classifier(.display_text).topics, .name == 'E-Signature')
          or regex.icontains(.display_text,
                             '\b(?:view|open|review|access|download|see|shared?)\b[^\n]{0,30}\b(?:document|doc|file|contract|invoice|statement|agreement|draft|attachment|folder)\b'
          )
        )
)
and any(ml.nlu_classifier(body.current_thread.text).intents,
        .name in ('cred_theft', 'bec') and .confidence != 'low'
)
and not (
  sender.email.domain.root_domain == 'evernote.com'
  and coalesce(headers.auth_summary.dmarc.pass, false)
)

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

Raw Content

name: "Service abuse: Evernote link"
description: "Detects inbound messages containing a link whose effective destination resolves to evernote.com, where the link text uses document-sharing or e-signature language (e.g., view, open, download, review) and the sender is not from evernote.com. The message body is also classified by an NLU model as exhibiting credential theft or business email compromise intent, indicating abuse of Evernote's legitimate hosting infrastructure to deliver malicious content."
type: "rule"
severity: "low"
source: |
  type.inbound
  // a link whose effective destination is evernote
  and any(body.current_thread.links,
          (
            .href_url.domain.root_domain == "evernote.com"
            or .display_url.domain.root_domain == "evernote.com"
            or any(.href_url.query_params_decoded["domain"],
                   strings.iends_with(., "evernote.com")
            )
          )
          and (
            any(ml.nlu_classifier(.display_text).topics, .name == 'E-Signature')
            or regex.icontains(.display_text,
                               '\b(?:view|open|review|access|download|see|shared?)\b[^\n]{0,30}\b(?:document|doc|file|contract|invoice|statement|agreement|draft|attachment|folder)\b'
            )
          )
  )
  and any(ml.nlu_classifier(body.current_thread.text).intents,
          .name in ('cred_theft', 'bec') and .confidence != 'low'
  )
  and not (
    sender.email.domain.root_domain == 'evernote.com'
    and coalesce(headers.auth_summary.dmarc.pass, false)
  )
attack_types:
  - "Credential Phishing"
  - "BEC/Fraud"
tactics_and_techniques:
  - "Social engineering"
detection_methods:
  - "URL analysis"
  - "Natural Language Understanding"
id: "72a4e9ba-fd02-5f7b-ac0f-af9b3ae8f35e"