Detection rules › Sublime MQL

Catbox.moe link from untrusted source

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

Detects messages containing links to catbox.moe file hosting service from senders who either aren't in highly trusted domains or failed DMARC authentication

Threat classification

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

CategoryValues
Attack typesMalware/Ransomware
Tactics and techniquesFree file host, Social engineering

Event coverage

Rule body MQL

type.inbound
and any(body.links,
        .href_url.domain.root_domain == "catbox.moe"
        and not strings.iends_with(.href_url.path, ".json")
)
// negate highly trusted sender domains unless they fail DMARC authentication
and (
  (
    sender.email.domain.root_domain in $high_trust_sender_root_domains
    and not coalesce(headers.auth_summary.dmarc.pass, false)
  )
  or sender.email.domain.root_domain not in $high_trust_sender_root_domains
)

Detection logic

Scope: inbound message.

Detects messages containing links to catbox.moe file hosting service from senders who either aren't in highly trusted domains or failed DMARC authentication

  1. inbound message
  2. any of body.links where all hold:
    • .href_url.domain.root_domain is 'catbox.moe'
    • not:
      • .href_url.path ends with '.json'
  3. any of:
    • all of:
      • sender.email.domain.root_domain in $high_trust_sender_root_domains
      • not:
        • coalesce(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, body.links[].href_url.path, headers.auth_summary.dmarc.pass, sender.email.domain.root_domain, type.inbound. Sensors: strings.iends_with. Reference lists: $high_trust_sender_root_domains.

Indicators matched (2)

FieldMatchValue
body.links[].href_url.domain.root_domainequalscatbox.moe
strings.iends_withsuffix.json