Detection rules › Sublime MQL

Open redirect: Signature Travel Network

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

Message contains use of the Signature Travel Network open redirect, but the sender is not Signature Travel Network. This has been exploited in the wild.

Threat classification

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

CategoryValues
Attack typesCredential Phishing
Tactics and techniquesOpen redirect

Event coverage

Rule body MQL

type.inbound
and any(body.links,
        .href_url.domain.root_domain == 'sigtn.com'
        and strings.iends_with(.href_url.path, "emt.cfm")
        and strings.icontains(.href_url.query_params, "link=")
)
and sender.email.domain.root_domain not in (
  'signaturetravelnetwork.com',
  'sigtn.com'
)
and not any(headers.domains, .root_domain == "signaturetravelnetwork.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 Signature Travel Network open redirect, but the sender is not Signature Travel Network. This has been exploited in the wild.

  1. inbound message
  2. any of body.links where all hold:
    • .href_url.domain.root_domain is 'sigtn.com'
    • .href_url.path ends with 'emt.cfm'
    • .href_url.query_params contains 'link='
  3. sender.email.domain.root_domain not in ('signaturetravelnetwork.com', 'sigtn.com')
  4. not:
    • any of headers.domains where:
      • .root_domain is 'signaturetravelnetwork.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.root_domain, body.links[].href_url.path, body.links[].href_url.query_params, headers.auth_summary.dmarc.pass, headers.domains, headers.domains[].root_domain, sender.email.domain.root_domain, type.inbound. Sensors: strings.icontains, strings.iends_with. Reference lists: $high_trust_sender_root_domains.

Indicators matched (6)

FieldMatchValue
body.links[].href_url.domain.root_domainequalssigtn.com
strings.iends_withsuffixemt.cfm
strings.icontainssubstringlink=
sender.email.domain.root_domainmembersignaturetravelnetwork.com
sender.email.domain.root_domainmembersigtn.com
headers.domains[].root_domainequalssignaturetravelnetwork.com