ESB-2019.0735 - [Appliance] IBM Cloud Kubernetes Service: Denial of service - Existing account 2019-03-08

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2019.0735
IBM Security Bulletin: IBM Cloud Kubernetes Service is affected by a Denial
             of Service vulnerability in Kubernetes API server
                               8 March 2019

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           IBM Cloud Kubernetes Service
Publisher:         IBM
Operating System:  Network Appliance
Impact/Access:     Denial of Service -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-1002100  

Original Bulletin: 
   http://www.ibm.com/support/docview.wss?uid=ibm10873324

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IBM Cloud Kubernetes Service is affected by a Denial of Service vulnerability
in Kubernetes API server

Product:             IBM Cloud Kubernetes Service

Component:           --

Software version:    All Versions

Operating system(s): Platform Independent

Reference #:         0873324

Security Bulletin

Summary

IBM Cloud Kubernetes Service is affected by a security vulnerability in
Kubernetes which could cause a Denial of Service on the API Server.

Vulnerability Details

CVEID: CVE-2019-1002100
DESCRIPTION: Users that are authorized to make patch requests to the Kubernetes
API Server can send a specially crafted patch of type "json-patch" (e.g.
`kubectl patch --type json` or `"Content-Type: application/json-patch+json"`)
that consumes excessive resources while processing, causing a Denial of Service
on the API Server.
CVSS Base Score: 6.5
CVSS Temporal Score:
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)

Affected Products and Versions

IBM Cloud Kubernetes Service 1.13.0-1.13.3
IBM Cloud Kubernetes Service 1.12.0-1.12.5
IBM Cloud Kubernetes Service 1.11.0-1.11.7
IBM Cloud Kubernetes Service 1.10.0-1.10.13
IBM Cloud Kubernetes Service 1.5-1.9

Remediation/Fixes

IBM Cloud Kubernetes Service clusters at versions 1.11 and later have been
updated to address this vulnerability. If your clusters are at versions 1.11,
1.12 or 1.13 there is no need to update worker nodes to address this
vulnerability.

In some situations IBM Cloud Kubernetes Service might not have been able to
update a cluster. To verify your clusters are no longer exposed use the
following IBM Cloud CLI command to confirm the currently running versions:

ibmcloud ks clusters

If your versions are at one of the following levels or later, you are no longer
exposed to this vulnerability:

1.11.8
1.12.6
1.13.4

If one or more of your clusters is at version 1.11, 1.12 or 1.13 and has not
been automatically updated then use the following IBM Cloud CLI command to
complete the update, replacing "1.##" with the target version:

ibmcloud ks cluster-update --cluster <cluster-name> --kube-version 1.##

Customers running IBM Cloud Kubernetes Service clusters at version 1.10 must
upgrade their affected clusters to version 1.11 or 1.12. Customers running IBM
Cloud Kubernetes Service clusters at version 1.7, 1.8 or 1.9 must upgrade first
to version 1.10 and then to version 1.11 or 1.12. To upgrade a cluster use the
following IBM Cloud CLI command, replacing "1.##" with the target version.
Please review the documentation before starting the upgrade since additional
actions may be required.

ibmcloud ks cluster-update --cluster <cluster-name> --kube-version 1.##

If you are running a version of IBM Cloud Kubernetes Service 1.5 there is no
migration path.

Note: IBM Cloud Kubernetes Service versions 1.5, 1.7, 1.8 and 1.9 are no longer
supported. See the IBM Cloud Kubernetes Service Version information and update
actions documentation for more information about Kubernetes versions and
version support policies.

Workarounds and Mitigations

Remove 'patch' permissions from untrusted users.

Reference

Complete CVSS v3 Guide
On-line Calculator v3

Related Information

IBM Secure Engineering Web Portal
IBM Product Security Incident Response Blog

*The CVSS Environment Score is customer environment specific and will
ultimately impact the Overall CVSS Score. Customers can evaluate the impact of
this vulnerability in their environments by accessing the links in the
Reference section of this Security Bulletin.

Disclaimer

According to the Forum of Incident Response and Security Teams (FIRST), the
Common Vulnerability Scoring System (CVSS) is an "industry open standard
designed to convey vulnerability severity and help to determine urgency and
priority of response." IBM PROVIDES THE CVSS SCORES ""AS IS"" WITHOUT WARRANTY
OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF
ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.

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