Detection rules › Sublime MQL

Open redirect: api.spently.com

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

Message contains use of the api.spently.com 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
// there are less than 10 unique links for api.spently.com within the body.links
and length(distinct(filter(body.links,
                           .href_url.domain.domain == "api.spently.com"
                    ),
                    .href_url.url
           )
) < 10
and any(body.links,
        .href_url.domain.domain == "api.spently.com"
        and strings.istarts_with(.href_url.path, '/api/spently/click')
        and strings.icontains(.href_url.query_params, 'url=')
        and strings.icontains(.href_url.query_params, 'type=')
        and not regex.icontains(.href_url.query_params,
                                'url=(?:https?(?:%3a|:))?(?:%2f|\/){2}[^&]*spently\.com(?:\&|\/|$|%2f)'
        )
)
and not sender.email.domain.root_domain == "spently.com"

// 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 api.spently.com redirect. This has been exploited in the wild.

  1. inbound message
  2. length(distinct(filter(body.links, .href_url.domain.domain == 'api.spently.com'), .href_url.url)) < 10
  3. any of body.links where all hold:
    • .href_url.domain.domain is 'api.spently.com'
    • .href_url.path starts with '/api/spently/click'
    • .href_url.query_params contains 'url='
    • .href_url.query_params contains 'type='
    • not:
      • .href_url.query_params matches 'url=(?:https?(?:%3a|:))?(?:%2f|\\/){2}[^&]*spently\\.com(?:\\&|\\/|$|%2f)'
  4. not:
    • sender.email.domain.root_domain is 'spently.com'
  5. 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.path, body.links[].href_url.query_params, headers.auth_summary.dmarc.pass, sender.email.domain.root_domain, type.inbound. Sensors: regex.icontains, strings.icontains, strings.istarts_with. Reference lists: $high_trust_sender_root_domains.

Indicators matched (6)

FieldMatchValue
body.links[].href_url.domain.domainequalsapi.spently.com
strings.istarts_withprefix/api/spently/click
strings.icontainssubstringurl=
strings.icontainssubstringtype=
regex.icontainsregexurl=(?:https?(?:%3a|:))?(?:%2f|\/){2}[^&]*spently\.com(?:\&|\/|$|%2f)
sender.email.domain.root_domainequalsspently.com