Detection rules › Sublime MQL

Open redirect: events.csiro.au

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

Message contains use of the events.csiro.au redirect. This has been exploited in the wild.

Threat classification

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

CategoryValues
Attack typesCredential Phishing, Malware/Ransomware
Tactics and techniquesOpen redirect

Event coverage

Rule body MQL

type.inbound
and any(body.links,
        .href_url.domain.domain == "events.csiro.au"
        and strings.icontains(.href_url.query_params, '&ec_url=')
        and not regex.icontains(.href_url.query_params,
                                '&ec_url=[^\&]*csiro\.au(?:\&|\/|$)'
        )
)
and not sender.email.domain.root_domain in ("csiro.au")

// 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.

Message contains use of the events.csiro.au redirect. This has been exploited in the wild.

  1. inbound message
  2. any of body.links where all hold:
    • .href_url.domain.domain is 'events.csiro.au'
    • .href_url.query_params contains '&ec_url='
    • not:
      • .href_url.query_params matches '&ec_url=[^\\&]*csiro\\.au(?:\\&|\\/|$)'
  3. not:
    • sender.email.domain.root_domain in ('csiro.au')
  4. 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.domain, body.links[].href_url.query_params, headers.auth_summary.dmarc.pass, sender.email.domain.root_domain, type.inbound. Sensors: regex.icontains, strings.icontains. Reference lists: $high_trust_sender_root_domains.

Indicators matched (4)

FieldMatchValue
body.links[].href_url.domain.domainequalsevents.csiro.au
strings.icontainssubstring&ec_url=
regex.icontainsregex&ec_url=[^\&]*csiro\.au(?:\&|\/|$)
sender.email.domain.root_domainmembercsiro.au