Open redirect: adnxs.com

name: "Open redirect: adnxs.com"
description: |
  Message contains use of the adnxs.com redirect with getuid parameter. This has been exploited in phishing campaigns to redirect users to malicious sites.
type: "rule"
severity: "medium"
source: |
  type.inbound
  and any(body.links,
          (
            .href_url.domain.domain == "ib.adnxs.com"
            and strings.icontains(.href_url.path, '/getuid')
            // Make sure the redirect is not going back to adnxs.com
            and not regex.icontains(.href_url.query_params,
                                    'getuid\?(?:https?(?:%3a|:))?(?:%2f|\/){2}[^&]*adnxs\.com(?:\&|\/|$|%2f)'
            )
          )
          // second form of an open redirect
          or (
            .href_url.domain.domain == "secure.adnxs.com"
            and strings.icontains(.href_url.query_params, 'redir=')
            // Make sure the redirect is not going back to adnxs.com
            and not regex.icontains(.href_url.query_params,
                                    'redir=(?:https?(?:%3a|:))?(?:%2f|\/){2}[^&]*adnxs\.com(?:\&|\/|$|%2f)'
            )
          )
  )
  and not sender.email.domain.root_domain == "adnxs.com"
  and not sender.email.domain.root_domain == "appnexus.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: "7fc92916-6c7a-53dd-9487-22b11ee062b3"