Detection rules › Sublime MQL

Twitter infrastructure abuse via link shortener

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

Email contains Twitter shortened link (t.co) but does not originate from a Twitter domain. This is a known malicious and spam tactic.

Threat classification

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

CategoryValues
Attack typesCredential Phishing, Malware/Ransomware, Spam
Tactics and techniquesEvasion, Impersonation: Brand, Social engineering

Event coverage

Rule body MQL

type.inbound
and length(body.links) < 10
and any(body.links, .href_url.domain.root_domain == "t.co")
and sender.email.domain.domain not in~ (
  'twitter.com',
  'x.com',
  'twitter.discoursemail.com'
)
and (
  not profile.by_sender_email().solicited
  or (
    profile.by_sender().any_messages_malicious_or_spam
    and not profile.by_sender().any_messages_benign
  )
)
// negate highly trusted sender domains unless they fail DMARC authentication
and (
  (
    sender.email.domain.root_domain in $high_trust_sender_root_domains
    and not headers.auth_summary.dmarc.pass
  )
  or sender.email.domain.root_domain not in $high_trust_sender_root_domains
)

Detection logic

Scope: inbound message.

Email contains Twitter shortened link (t.co) but does not originate from a Twitter domain. This is a known malicious and spam tactic.

  1. inbound message
  2. length(body.links) < 10
  3. any of body.links where:
    • .href_url.domain.root_domain is 't.co'
  4. sender.email.domain.domain not in ('twitter.com', 'x.com', 'twitter.discoursemail.com')
  5. any of:
    • not:
      • profile.by_sender_email().solicited
    • all of:
      • profile.by_sender().any_messages_malicious_or_spam
      • not:
        • profile.by_sender().any_messages_benign
  6. any of:
    • all of:
      • sender.email.domain.root_domain in $high_trust_sender_root_domains
      • not:
        • headers.auth_summary.dmarc.pass
    • sender.email.domain.root_domain not in $high_trust_sender_root_domains

Inspects: body.links, body.links[].href_url.domain.root_domain, headers.auth_summary.dmarc.pass, sender.email.domain.domain, sender.email.domain.root_domain, type.inbound. Sensors: profile.by_sender, profile.by_sender_email. Reference lists: $high_trust_sender_root_domains.

Indicators matched (4)

FieldMatchValue
body.links[].href_url.domain.root_domainequalst.co
sender.email.domain.domainmembertwitter.com
sender.email.domain.domainmemberx.com
sender.email.domain.domainmembertwitter.discoursemail.com