Detection rules › Sublime MQL

Open redirect: next2.io

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

Message contains use of a next.io redirect. This redirection has been abused by threat actors in the wild.

Threat classification

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

CategoryValues
Attack typesCredential Phishing
Tactics and techniquesEvasion, Open redirect, Social engineering

Event coverage

Rule body MQL

type.inbound
and any(body.links,
        .href_url.domain.domain == "c.next2.io"
        and .href_url.path =~ "/api/ads"
        and strings.icontains(.href_url.query_params, 'fallback_url=')
)

// 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 a next.io redirect. This redirection has been abused by threat actors in the wild.

  1. inbound message
  2. any of body.links where all hold:
    • .href_url.domain.domain is 'c.next2.io'
    • .href_url.path is '/api/ads'
    • .href_url.query_params contains 'fallback_url='
  3. 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: strings.icontains. Reference lists: $high_trust_sender_root_domains.

Indicators matched (3)

FieldMatchValue
body.links[].href_url.domain.domainequalsc.next2.io
body.links[].href_url.pathequals/api/ads
strings.icontainssubstringfallback_url=