Medium Severity
Credential Phishing via Dropbox comment abuse
Description
This rule detects Credential Phishing attacks exploiting familiar brands via Dropbox comments. These attacks originate from legitimate Dropbox infrastructure and attempt to pivot to external freemail addresses.
References
No references.
Sublime Security
Created Jan 16th, 2024 • Last updated Apr 23rd, 2024
Feed Source
Sublime Core Feed
Source
type.inbound
and length(attachments) == 0
// Legitimate Dropbox sending infratructure
and (
sender.email.domain.root_domain in ('dropbox.net', 'dropbox.com')
// check for DMARC fail for spoofs
and headers.auth_summary.dmarc.pass
)
// Dropbox Logo or text
and (
any(ml.logo_detect(beta.message_screenshot()).brands, .name == "Dropbox")
or strings.contains(body.current_thread.text, "Dropbox")
)
// Require common brand impersonation
and strings.ilike(body.current_thread.text,
"*mcafee*",
"*norton*",
"*geek*squad*",
"*paypal*",
"*ebay*",
"*symantec*",
"*best buy*",
"*lifelock*",
"*geek*support*"
)
and 3 of (
strings.ilike(body.current_thread.text, '*purchase*'),
strings.ilike(body.current_thread.text, '*payment*'),
strings.ilike(body.current_thread.text, '*transaction*'),
strings.ilike(body.current_thread.text, '*subscription*'),
strings.ilike(body.current_thread.text, '*antivirus*'),
strings.ilike(body.current_thread.text, '*order*'),
strings.ilike(body.current_thread.text, '*support*'),
strings.ilike(body.current_thread.text, '*help line*'),
strings.ilike(body.current_thread.text, '*receipt*'),
strings.ilike(body.current_thread.text, '*invoice*'),
strings.ilike(body.current_thread.text, '*call*'),
strings.ilike(body.current_thread.text, '*cancel*'),
strings.ilike(body.current_thread.text, '*renew*'),
strings.ilike(body.current_thread.text, '*refund*'),
strings.ilike(body.current_thread.text, '*transfer*'),
strings.ilike(body.current_thread.text, '*message*')
)
// there's an email in the body
and regex.contains(body.current_thread.text,
"[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}"
)
// and it's likely a freemail
and any($free_email_providers, strings.icontains(body.current_thread.text, .))
Playground
Test against your own EMLs or sample data.