Detection rules › Sublime MQL

Google services using g.co shortlinks

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

Identifies messages from authenticated Google domains containing g.co shortened URLs with a subdomain in either the message body links or thread text.

Threat classification

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

CategoryValues
Attack typesCredential Phishing
Tactics and techniquesEvasion, Free email provider

Event coverage

Rule body MQL

type.inbound
// allow for multiple google TLDs
and sender.email.domain.sld == "google"
and headers.auth_summary.spf.pass
// g.co url shortner in links or the current thread to identify the workspace name
and (
  any(body.links,
      .href_url.domain.root_domain == 'g.co'
      and .href_url.domain.subdomain is not null
  )
  or (
    strings.icontains(body.current_thread.text, '.g.co')
    and regex.icontains(body.current_thread.text, '[^\s]+\.g\.co\b')
  )
)

Detection logic

Scope: inbound message.

Identifies messages from authenticated Google domains containing g.co shortened URLs with a subdomain in either the message body links or thread text.

  1. inbound message
  2. sender.email.domain.sld is 'google'
  3. headers.auth_summary.spf.pass
  4. any of:
    • any of body.links where all hold:
      • .href_url.domain.root_domain is 'g.co'
      • .href_url.domain.subdomain is set
    • all of:
      • body.current_thread.text contains '.g.co'
      • body.current_thread.text matches '[^\\s]+\\.g\\.co\\b'

Inspects: body.current_thread.text, body.links, body.links[].href_url.domain.root_domain, body.links[].href_url.domain.subdomain, headers.auth_summary.spf.pass, sender.email.domain.sld, type.inbound. Sensors: regex.icontains, strings.icontains.

Indicators matched (4)

FieldMatchValue
sender.email.domain.sldequalsgoogle
body.links[].href_url.domain.root_domainequalsg.co
strings.icontainssubstring.g.co
regex.icontainsregex[^\s]+\.g\.co\b