Fake email quarantine notification

  1name: "Fake email quarantine notification"
  2description: "Detects phishing messages implying that emails have been delayed or blocked, prompting users to view, release, or delete pending messages."
  3type: "rule"
  4severity: "high"
  5source: |
  6  type.inbound
  7  and length(body.links) < 10
  8  and (
  9    any(ml.nlu_classifier(body.current_thread.text).intents,
 10        .name == "cred_theft" and .confidence == "high"
 11    )
 12    or (
 13      length(body.current_thread.text) < 250
 14      and any(recipients.to,
 15              strings.icontains(body.current_thread.text, .email.domain.sld)
 16              or strings.icontains(body.current_thread.text, .email.local_part)
 17      )
 18    )
 19  )
 20  and 3 of (
 21    strings.ilike(body.current_thread.text, "*review*"),
 22    strings.ilike(body.current_thread.text, "*incoming*"),
 23    strings.ilike(body.current_thread.text, "*release*"),
 24    strings.ilike(body.current_thread.text, "*quarantine*"),
 25    strings.ilike(body.current_thread.text, "*messages*"),
 26    strings.ilike(body.current_thread.text, "*server error*"),
 27    strings.ilike(body.current_thread.text, "*blocked*"),
 28    strings.ilike(body.current_thread.text, "*prevented*"),
 29    strings.ilike(body.current_thread.text, "*notification*"),
 30    strings.ilike(body.current_thread.text, "*kindly*"),
 31    strings.ilike(body.current_thread.text, "*on hold*"),
 32    strings.ilike(body.current_thread.text, "*held*"),
 33    strings.ilike(body.current_thread.text, "*pending*")
 34  )
 35  and (
 36    any(body.links,
 37        regex.icontains(.display_text, "view", "release", "messages", "delete", "recover")
 38    )
 39    or (
 40      length(body.links) < 3
 41      and any(body.links,
 42              any(recipients.to,
 43                  .email.domain.root_domain == ..display_url.domain.root_domain
 44                  and ..mismatched
 45              )
 46      )
 47    )
 48  )
 49  and not any(body.links,
 50              regex.icontains(.display_text,
 51                              "view document",
 52                              "review (&|and) sign document"
 53              )
 54  )
 55  and sender.email.domain.root_domain not in (
 56    "bing.com",
 57    "microsoft.com",
 58    "microsoftonline.com",
 59    "microsoftsupport.com",
 60    "microsoft365.com",
 61    "office.com",
 62    "office365.com",
 63    "onedrive.com",
 64    "sharepointonline.com",
 65    "yammer.com",
 66    "ppops.net"
 67  )
 68  
 69  // negate org domains unless they fail DMARC authentication
 70  and (
 71    (
 72      sender.email.domain.root_domain in $org_domains
 73      and (
 74        not headers.auth_summary.dmarc.pass
 75        // MS quarantine digest emails from an org domain are router "internally" to MS, therefore, there is no authentication information
 76        or not (
 77          headers.auth_summary.dmarc.pass is null
 78          and all(headers.domains,
 79                  .root_domain in ("outlook.com", "office365.com")
 80          )
 81          // typical emails from freemail Outlook accounts are from prod.outlook.com
 82          and strings.ends_with(headers.message_id, "protection.outlook.com>")
 83        )
 84      )
 85    )
 86    or sender.email.domain.root_domain not in $org_domains
 87  )
 88  
 89  // negate highly trusted sender domains unless they fail DMARC authentication
 90  and (
 91    (
 92      sender.email.domain.root_domain in $high_trust_sender_root_domains
 93      and not headers.auth_summary.dmarc.pass
 94    )
 95    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
 96  )
 97  and not profile.by_sender().solicited
 98  and not profile.by_sender().any_false_positives
 99    
100attack_types:
101  - "Credential Phishing"
102tactics_and_techniques:
103  - "Social engineering"
104detection_methods:
105  - "Content analysis"
106  - "Natural Language Understanding"
107  - "Sender analysis"
108id: "73f26a3d-b7a5-5b85-83e6-45f1b40f78fb"