Detection rules › Sublime MQL

Russia return-path TLD (untrusted sender)

Severity
low
Type
rule
Source
github.com/sublime-security/sublime-rules

The return-path header is a .ru TLD from an untrusted sender.

Threat classification

Sublime's own taxonomy (not MITRE ATT&CK).

CategoryValues
Attack typesBEC/Fraud, Credential Phishing, Malware/Ransomware

Event coverage

Rule body MQL

type.inbound
and headers.return_path.domain.tld == "ru"
and sender.email.domain.domain != "corp.mail.ru"
and sender.email.domain.domain != "calendar.yandex.ru"
and (
  (
    profile.by_sender().prevalence in ("new", "outlier")
    and not profile.by_sender().solicited
  )
  or (
    profile.by_sender().any_messages_malicious_or_spam
    and not profile.by_sender().any_messages_benign
  )
)
and not profile.by_sender().any_messages_benign

Detection logic

Scope: inbound message.

The return-path header is a .ru TLD from an untrusted sender.

  1. inbound message
  2. headers.return_path.domain.tld is 'ru'
  3. sender.email.domain.domain is not 'corp.mail.ru'
  4. sender.email.domain.domain is not 'calendar.yandex.ru'
  5. any of:
    • all of:
      • profile.by_sender().prevalence in ('new', 'outlier')
      • not:
        • profile.by_sender().solicited
    • all of:
      • profile.by_sender().any_messages_malicious_or_spam
      • not:
        • profile.by_sender().any_messages_benign
  6. not:
    • profile.by_sender().any_messages_benign

Inspects: headers.return_path.domain.tld, sender.email.domain.domain, type.inbound. Sensors: profile.by_sender.

Indicators matched (1)

FieldMatchValue
headers.return_path.domain.tldequalsru