Service Abuse: Box file sharing with credential phishing intent

name: "Service Abuse: Box file sharing with credential phishing intent"
description: "Detects abuse of Box's legitimate infrastructure for credential phishing attacks."
type: "rule"
severity: "medium"
source: |
  type.inbound
  
  // Legitimate Box sending infrastructure
  and sender.email.domain.root_domain == "box.com"
  
  // ML classification indicates credential theft with high confidence
  and (
    any(ml.nlu_classifier(body.current_thread.text).intents,
        .name == "cred_theft" and .confidence == "high"
    )
    // Link analysis for credential phishing detection
    or any(filter(body.links,
                  // target the box link
                  (
                    .href_url.domain.domain == "app.box.com"
                  )
           ),
           ml.link_analysis(., mode="aggressive").credphish.disposition == "phishing"
           and ml.link_analysis(., mode="aggressive").credphish.confidence in (
             "medium",
             "high"
           )
    )
  )
  // Box file sharing patterns
  and (
    strings.icontains(subject.subject, 'invited you to')
    or strings.icontains(subject.subject, 'shared')
    or strings.icontains(subject.subject, 'has sent you')
    or strings.icontains(body.current_thread.text, 'Go to File')
    or any(body.links, strings.icontains(.display_text, 'Go to File'))
  )
  
  // Suspicious document patterns or VIP impersonation
  and (
    // Financial document patterns
    (
      regex.icontains(subject.subject,
                      '\b(fund|portfolio|agreement|contract|proposal|invoice|payment|wire|settlement|billing|timesheet|hr)\b'
      )
      or regex.icontains(body.current_thread.text,
                         '\b(fund|portfolio|agreement|contract|proposal|invoice|payment|wire|settlement|billing|timesheet|hr)\b'
      )
      or any(body.links,
             regex.icontains(.display_text,
                             '\b(fund|portfolio|agreement|contract|proposal|invoice|payment|wire|settlement|billing|timesheet|hr)\b'
             )
      )
    )
    // Corporate document patterns
    or (
      regex.icontains(subject.subject,
                      '\b(urgent|important|confidential|secure|encrypted|document|file)\b'
      )
      and regex.icontains(subject.subject,
                          '\b(review|approval|signature|verification|validation)\b'
      )
    )
  )
attack_types:
  - "Credential Phishing"
  - "BEC/Fraud"
  - "Callback Phishing"
tactics_and_techniques:
  - "Evasion"
  - "Social engineering"
  - "Impersonation: Employee"
  - "Impersonation: VIP"
detection_methods:
  - "Content analysis"
  - "Natural Language Understanding"
  - "Sender analysis"
  - "Header analysis"
id: "5bd0cb25-5984-5f52-9b7b-d7d337eacf7a"