Open redirect: Medium

name: "Open redirect: Medium"
description: |
  Message contains use of the Medium open redirect. This has been exploited in the wild.
type: "rule"
severity: "medium"
source: |
  type.inbound
  and any(body.links,
          .href_url.domain.root_domain == "medium.com"
          and strings.icontains(.href_url.path, "/global-identity-2")
          and strings.icontains(.href_url.query_params, "redirectUrl=")
          // negate redirects to medium.com
          and not regex.icontains(.href_url.query_params,
                                  'redirectUrl=(?:(?:https?(?:%3a|:))?(?:%2f|\/){2})?(?:[a-z0-9]+\.)*medium\.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
  )
attack_types:
  - "Credential Phishing"
  - "Malware/Ransomware"
tactics_and_techniques:
  - "Open redirect"
detection_methods:
  - "Sender analysis"
  - "URL analysis"
id: "18c6aa1b-dee4-5ca6-a3bd-706cc7368e28"