Bug 1920764 (CVE-2021-20198)

Summary:	CVE-2021-20198 openshift/installer: Bootstrap nodes allow anonymous authentication on kubelet port 10250
Product:	[Other] Security Response	Reporter:	Sam Fowler <sfowler>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	aos-bugs, aos-install, bmontgom, dramseur, eparis, jburrell, jhunter, jminter, jokerman, jrussell, kmitts, mgala, mjudeiki, mstaeble, nstielau, rphillips, sdodson, security-response-team, sfowler, skuznets, sponnaga, wking
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	github.com/openshift/installer v0.9.0-master.0.20210125200451-95101da940b0	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in the OpenShift Installer. During installation of OpenShift Container Platform 4 clusters, bootstrap nodes are provisioned with anonymous authentication enabled on kubelet port 10250. A remote attacker able to reach this port during installation can make unauthenticated `/exec` requests to execute arbitrary commands within running containers. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-02-08 14:41:51 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1920243, 1920253, 1920766, 1920767, 1922873
Bug Blocks:	1920522, 1926375

Description Sam Fowler 2021-01-27 01:39:31 UTC

During the installation of OpenShift Container Platform 4 clusters, bootstrap nodes are provisioned with anonymous authentication enabled on kubelet port 10250. A remote attacker able to reach this port during installation can make unauthenticated `/exec` requests to execute arbitrary commands within running containers. 

Bootstrap nodes are automatically removed when deployed with Installer Provisioned Infrastructure (IPI) and typically exist for less than an hour. Clusters deployed with User Provisioned Infrastructure (UPI) require an administrator to remove or reconfigure bootstrap nodes. Additionally, on AWS, Azure, GCP and OpenStack port 10250 is not remotely accessible on bootstrap nodes, due to security group configuration.

Comment 5 Sam Fowler 2021-01-27 04:52:13 UTC

Upstream fix:

https://github.com/openshift/installer/pull/4590

Comment 7 Sam Fowler 2021-02-04 06:27:25 UTC

Mitigation:

This issue is mitigated by default on AWS, Azure, GCP and OpenStack as port 10250 is not remotely accessible on bootstrap nodes. For other IPI platforms, bootstrap nodes only exist during the installation window so the exposure is limited. For UPI installations, administrators should prevent remote access to this port on bootstrap nodes and/or remove the nodes once installation is complete

Comment 8 errata-xmlrpc 2021-02-08 13:50:41 UTC

This issue has been addressed in the following products:

  Red Hat OpenShift Container Platform 4.6

Via RHSA-2021:0308 https://access.redhat.com/errata/RHSA-2021:0308

Comment 9 Product Security DevOps Team 2021-02-08 14:41:51 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2021-20198

Comment 10 errata-xmlrpc 2021-02-09 13:34:09 UTC

This issue has been addressed in the following products:

  Red Hat OpenShift Container Platform 4.5

Via RHSA-2021:0313 https://access.redhat.com/errata/RHSA-2021:0313