Open redirect: emp.eduyield.com

name: "Open redirect: emp.eduyield.com"
description: |
  Message contains use of the eduyield redirect which chains google amp. This has been exploited in the wild.
type: "rule"
severity: "medium"
source: |
  type.inbound
  and any(body.links,
          .href_url.domain.domain == "emp.eduyield.com"
          // the redirect field
          and strings.icontains(.href_url.query_params, "&dest=")
          and regex.icontains(.href_url.query_params,
                              '&dest=(?:https?)?(?:(?:%3a|\:)?(?:\/|%2f){2})?google\.com[^\&]*\/+amp\/+(s\/+)?'
          )
  )
  and (
    not profile.by_sender().solicited
    or (
      profile.by_sender().any_messages_malicious_or_spam
      and not profile.by_sender().any_messages_benign
    )
  )
  
  // 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
  )
attack_types:
  - "Credential Phishing"
  - "Malware/Ransomware"
tactics_and_techniques:
  - "Open redirect"
detection_methods:
  - "Sender analysis"
  - "URL analysis"
id: "860e1381-a99a-5b6e-bfed-ef0931e06fc7"