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TEST - Update suspicious_request_for_quote_or_purchase.yml #921

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TEST - Update suspicious_request_for_quote_or_purchase.yml #921

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52 changes: 43 additions & 9 deletions detection-rules/suspicious_request_for_quote_or_purchase.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -6,17 +6,27 @@ type: "rule"
severity: "medium"
source: |
type.inbound
and 1 of (
(
(length(recipients.to) == 0 or all(recipients.to, .display_name == "Undisclosed recipients"))
and length(recipients.cc) == 0
and length(recipients.bcc) == 0
),
and (
(
length(recipients.to) == 0
or all(recipients.to,
.display_name == "Undisclosed recipients"
and length(recipients.cc) == 0
and length(recipients.bcc) == 0
)
)
or (
sender.email.domain.root_domain in $free_email_providers
and any(headers.reply_to, .email.email != sender.email.email)
and any(headers.reply_to, .email.email not in $recipient_emails)
)
or (
profile.by_sender().prevalence in ("new", "outlier")
or (
profile.by_sender().any_messages_malicious_or_spam
and not profile.by_sender().any_false_positives
)
)
)
and 2 of (
(
Expand All @@ -29,9 +39,21 @@ source: |
'(sign(ed?)|view).{0,10}(purchase order)|Request for a Quot(e|ation)'
)
),
(regex.icontains(coalesce(body.html.display_text, body.plain.raw), '(please|kindly).{0,30}quote')),
(regex.icontains(subject.subject, '(request for (purchase|quot(e|ation))|\bRFQ\b|\bRFP\b)')),
(any(attachments, regex.icontains(.file_name, "(purchase.?order|Quot(e|ation))"))),
(
regex.icontains(coalesce(body.html.display_text, body.plain.raw),
'(please|kindly).{0,30}quote'
)
),
(
regex.icontains(subject.subject,
'(request for (purchase|quot(e|ation))|\bRFQ\b|\bRFP\b)'
)
),
(
any(attachments,
regex.icontains(.file_name, "(purchase.?order|Quot(e|ation))")
)
),
(
any(ml.nlu_classifier(coalesce(body.html.display_text, body.plain.raw)).entities,
.name == "request"
Expand All @@ -46,6 +68,18 @@ source: |
)
)
)
// negate highly trusted sender domains unless they fail DMARC authentication
and (
(
sender.email.domain.root_domain in $high_trust_sender_root_domains
and (
any(distinct(headers.hops, .authentication_results.dmarc is not null),
strings.ilike(.authentication_results.dmarc, "*fail")
)
)
)
or sender.email.domain.root_domain not in $high_trust_sender_root_domains
)
attack_types:
- "BEC/Fraud"
tactics_and_techniques:
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