sublimemediumRule

New link domain (<=10d) from untrusted sender

Detects links in the body of an email where the linked domain is less than 10 days old from untrusted senders.

MITRE ATT&CK

T1566 T1566.001 T1566.002 T1598 T1204.002 T1486

Detection Query

type.inbound
and length(body.links) > 0
and any(body.links, network.whois(.href_url.domain).days_old <= 10)
and (
  (
    profile.by_sender().prevalence in ("new", "outlier")
    and not profile.by_sender().solicited
  )
  or profile.by_sender().any_messages_malicious_or_spam
)
// negate senders which have had previous messages marked as benign which pass auth
and not (
  profile.by_sender().any_messages_benign
  and profile.by_sender().auth_failed == false
)

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

Tags

Attack surface reduction

Raw Content

name: "New link domain (<=10d) from untrusted sender"
description: |
  Detects links in the body of an email where the linked domain is less than 10 days old from untrusted senders.
type: "rule"
severity: "medium"
source: |
  type.inbound
  and length(body.links) > 0
  and any(body.links, network.whois(.href_url.domain).days_old <= 10)
  and (
    (
      profile.by_sender().prevalence in ("new", "outlier")
      and not profile.by_sender().solicited
    )
    or profile.by_sender().any_messages_malicious_or_spam
  )
  // negate senders which have had previous messages marked as benign which pass auth
  and not (
    profile.by_sender().any_messages_benign
    and profile.by_sender().auth_failed == false
  )
tags:
  - "Attack surface reduction"
attack_types:
  - "Credential Phishing"
  - "Malware/Ransomware"
detection_methods:
  - "Sender analysis"
  - "URL analysis"
  - "Whois"
id: "4805b0e6-6d35-512b-8053-87dd0edacc8a"