Sensitive Information Disclosure in "_internal" index in Splunk Enterprise

In Splunk Enterprise versions below 10.2.0, 10.0.2, 9.4.7, 9.3.9, and 9.2.11, a user of a Splunk Search Head Cluster (SHC) deployment who holds a role with access to the Splunk _internal index could view the integrationKey, secretKey, and appSecretKey secrets, generated by Duo Two-Factor Authentication for Splunk Enterprise, in plain text.