Splunk Enterprise deployment servers allow unauthenticated forwarder bundle downloads

Description

Splunk Enterprise deployment servers in versions before 9.0 allow unauthenticated downloading of forwarder bundles. Remediation requires you to update the deployment server to version 9.0 and [Configure authentication for deployment servers and clients](https://docs.splunk.com/Documentation/Splunk/9.0.0/Security/ConfigDSDCAuthEnhancements. Once enabled, deployment servers can manage only universal forwarder versions 9.0 and later. Though the vulnerability does not directly affect Universal Forwarders, remediation requires updating all Universal Forwarders that the deployment server manages to version 9.0 or higher prior to enabling the remediation.

The Splunk Cloud Platform (SCP) does not offer or use deployment servers and is not affected by the vulnerability. For SCP customers that run deployment servers, upgrade to version 9.0 or higher. At the time of publishing, we have no evidence of exploitation of this vulnerability by external parties.

Solution

Upgrade Splunk Enterprise deployment servers to version 9.0 or higher, upgrade Universal Forwarders to version 9.0 or higher, and Configure authentication for deployment servers and clients.

Product Status

Severity Considerations

If you do not run a Deployment Server or use the Deployment Server functionality, the vulnerability is informational. You can disable the Deployment Server functionality temporarily without disabling the server. See CLI admin commands for more information.

The severity assumes the information contained within the forwarder bundle is highly confidential and sensitive such as certificates and passwords. Most app bundles do not meet that qualification. For most app bundles containing standard code and public apps, the severity is reduced to Medium. If you classify the forwarder bundle as public information, the severity is reduced to informational.

If the Deployment Server is within a VPC/VPN and only available within that adjacent boundary, Splunk recommends reducing the severity to Medium.

Acknowledgments

Nadim Taha at Splunk

Paul Schultze at E.ON Digital Technology GmbH

Martin Müller at Consist

Changelog

2022-07-18: Added Components in the Product Status table, the Severity Considerations, and Paul Schultze and Martin Müller to the Acknowledgments