Detection rules › Sublime MQL

Link: Non-standard port 8443 in display URL

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

Detects links containing port 8443 in the display URL, which may indicate suspicious redirect or hosting infrastructure.

Threat classification

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

CategoryValues
Attack typesCredential Phishing, Malware/Ransomware
Tactics and techniquesEvasion

Event coverage

Rule body MQL

type.inbound
and (
  // no previous threads
  length(body.previous_threads) == 0
  // or is a fake thread
  or (
    (length(headers.references) == 0 or headers.in_reply_to is null)
    and (
      subject.is_reply
      or subject.is_forward
      or length(body.previous_threads) > 0
    )
  )
)
and any(body.links,
        strings.contains(.display_url.url, ':8443')
        and network.whois(.href_url.domain).days_old <= 365
)

// Negate noreply-spamdigest senders
and not (
  sender.email.email == "noreply-spamdigest@google.com"
  and headers.auth_summary.dmarc.pass
)

Detection logic

Scope: inbound message.

Detects links containing port 8443 in the display URL, which may indicate suspicious redirect or hosting infrastructure.

  1. inbound message
  2. any of:
    • length(body.previous_threads) is 0
    • all of:
      • any of:
        • length(headers.references) is 0
        • headers.in_reply_to is missing
      • any of:
        • subject.is_reply
        • subject.is_forward
        • length(body.previous_threads) > 0
  3. any of body.links where all hold:
    • .display_url.url contains ':8443'
    • network.whois(.href_url.domain).days_old ≤ 365
  4. not:
    • all of:
      • sender.email.email is 'noreply-spamdigest@google.com'
      • headers.auth_summary.dmarc.pass

Inspects: body.links, body.links[].display_url.url, body.links[].href_url.domain, body.previous_threads, headers.auth_summary.dmarc.pass, headers.in_reply_to, headers.references, sender.email.email, subject.is_forward, subject.is_reply, type.inbound. Sensors: network.whois, strings.contains.

Indicators matched (2)

FieldMatchValue
strings.containssubstring:8443
sender.email.emailequalsnoreply-spamdigest@google.com