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Update link_microsoft_low_reputation.yml #908

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merged 2 commits into from
Nov 7, 2023
Merged

Update link_microsoft_low_reputation.yml #908

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158fc62
Update link_microsoft_low_reputation.yml
morriscode Nov 3, 2023
98a130a
Merge branch 'main' into morriscode-patch-3
morriscode Nov 6, 2023
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69 changes: 53 additions & 16 deletions detection-rules/link_microsoft_low_reputation.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -14,10 +14,18 @@ source: |
or

// mass mailer link, masks the actual URL
.href_url.domain.root_domain in ("hubspotlinks.com", "mandrillapp.com", "sendgrid.net")
.href_url.domain.root_domain in (
"hubspotlinks.com",
"mandrillapp.com",
"sendgrid.net",
"rs6.net"
)

// Google AMP redirect
or (.href_url.domain.sld == "google" and strings.starts_with(.href_url.path, "/amp/"))
or (
.href_url.domain.sld == "google"
and strings.starts_with(.href_url.path, "/amp/")
)
)

// exclude sources of potential FPs
Expand Down Expand Up @@ -47,7 +55,9 @@ source: |
.file_type in $file_types_images
and any(ml.logo_detect(.).brands, strings.starts_with(.name, "Microsoft"))
)
or any(ml.logo_detect(beta.message_screenshot()).brands, strings.starts_with(.name, "Microsoft"))
or any(ml.logo_detect(beta.message_screenshot()).brands,
strings.starts_with(.name, "Microsoft")
)
)

// suspicious content
Expand Down Expand Up @@ -105,7 +115,34 @@ source: |
)
)
)
or (
any(file.explode(beta.message_screenshot()),
strings.ilike(.scan.ocr.raw,
"*password*",
"*document*",
"*voicemail*",
"*cache*",
"*fax*",
"*storage*",
"*quota*",
"*messages*"
)
and strings.ilike(.scan.ocr.raw,
"*terminated*",
"*review*",
"*expire*",
"*click*",
"*view*",
"*exceed*",
"*clear*",
"*only works*",
"*failed*",
"*deleted*"
)
)
)
)

and (
any(ml.nlu_classifier(body.current_thread.text).intents,
.name == "cred_theft" and .confidence in~ ("medium", "high")
Expand Down Expand Up @@ -136,20 +173,20 @@ source: |
"sharepointonline.com",
"yammer.com"
)

// 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
)

// 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:
- "Credential Phishing"
Expand Down
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