• Sublime Core Feed
Medium Severity

Sender: IP address in local part

Description

Detects messages where the sender's email local part contains an IPv4 address, which is commonly used in malicious campaigns to bypass filters or appear legitimate.

References

No references.

Sublime Security
Created Mar 12th, 2026 • Last updated Mar 12th, 2026
Source
type.inbound
and length(body.current_thread.text) > 100
and regex.icontains(sender.email.local_part,
                    '(?:\d{1,3}\.){3}\d{1,3}[^\.][[:alpha:]]+',
                    '[[:alpha:]]+(?:\d{1,3}\.){3}\d{1,3}[^\.]'
)
and not (
  strings.ilike(sender.email.local_part, "*report*", "*abuse*")
  or any(ml.nlu_classifier(body.current_thread.text).topics,
         .name == "Bounce Back and Delivery Failure Notifications"
         and .confidence != "low"
  )
)
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