High Severity
Attachment: Microsoft impersonation via PDF with link and suspicious language
Description
Attached PDF contains a Microsoft-affilated logo, suspicious language or keywords, and a link. Known malware delivery method.
References
No references.
Sublime Security
Created Dec 19th, 2023 • Last updated May 2nd, 2024
Feed Source
Sublime Core Feed
Source
type.inbound
and (
any(attachments,
(.file_extension == "pdf" or .file_type == "pdf")
and any(ml.logo_detect(.).brands, strings.starts_with(.name, "Microsoft"))
)
)
and any(attachments,
(.file_extension == "pdf" or .file_type == "pdf")
and any(file.explode(.),
(
length(filter([
"password",
"unread messages",
"Shared Documents",
"expiration",
"expire",
"expiring",
"kindly",
"renew",
"review",
"emails failed",
"kicked out",
"prevented",
"storage",
"required now",
"cache",
"qr code",
"security update",
"invoice",
"retrieve",
'engine failed',
'OneDrive Error',
'problem connecting',
'secure file',
'access'
],
strings.icontains(..scan.ocr.raw, .)
)
) >= 2
or any(ml.nlu_classifier(.scan.ocr.raw).intents,
.name == "cred_theft" and .confidence == "high"
)
)
and (length(.scan.url.urls) > 0 or length(.scan.pdf.urls) > 0)
)
)
and (
not any(headers.hops,
.authentication_results.compauth.verdict is not null
and .authentication_results.compauth.verdict == "pass"
and sender.email.domain.domain in (
"microsoft.com",
"sharepointonline.com"
)
)
)
and (
not profile.by_sender().solicited
or (
profile.by_sender().any_messages_malicious_or_spam
and not profile.by_sender().any_false_positives
)
)
// negate highly trusted sender domains unless they fail DMARC authentication
and (
(
sender.email.domain.root_domain in $high_trust_sender_root_domains
and not headers.auth_summary.dmarc.pass
)
or sender.email.domain.root_domain not in $high_trust_sender_root_domains
)
and not profile.by_sender().any_false_positives
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