ESB-2019.0211 - [Appliance] Citrix: Access privileged data - Remote/unauthenticated 2019-01-24

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2019.0211
          TLS Padding Oracle Vulnerability in Citrix Application
              Delivery Controller(ADC) and NetScaler Gateway
                              24 January 2019

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

Product:           Citrix Application Delivery Controller
                   Citrix NetScaler Gateway
Publisher:         Citrix
Operating System:  Network Appliance
Impact/Access:     Access Privileged Data -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-6485  

Original Bulletin: 
   https://support.citrix.com/article/CTX240139

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Security Bulletin: TLS Padding Oracle Vulnerability in Citrix Application 
Delivery Controller(ADC) and NetScaler Gateway

Reference:CTX240139

Applicable Products

  o NetScaler 12.1
  o NetScaler 12.0
  o NetScaler 11.1
  o NetScaler 11.0
  o NetScaler 10.5
  o NetScaler Gateway 12.0
  o NetScaler Gateway 11.1
  o NetScaler Gateway 11.0
  o NetScaler Gateway 10.5

Description of Problem

A vulnerability has been identified in the Citrix Application Delivery
Controller (ADC) formally known as NetScaler ADC and NetScaler Gateway
platforms using hardware acceleration that could allow an attacker to exploit
the appliance to decrypt TLS traffic. This vulnerability does not directly
allow an attacker to obtain the TLS private key.

This vulnerability has been assigned the following CVE:

o CVE-2019-6485: TLS Padding Oracle Vulnerability in Citrix Application
Delivery Controller (ADC) and NetScaler Gateway

Platforms not on the list below and running the following versions of Citrix
ADC and NetScaler Gateway are impacted, including Citrix ADC instances on
affected SDX platforms using hardware acceleration via an assigned virtual
function (VF):

o Citrix ADC and NetScaler Gateway version 12.1 earlier than build 50.31

o Citrix ADC and NetScaler Gateway version 12.0 earlier than build 60.9

o Citrix ADC and NetScaler Gateway version 11.1 earlier than build 60.14

o Citrix ADC and NetScaler Gateway version 11.0 earlier than build 72.17

o Citrix ADC and NetScaler Gateway version 10.5 earlier than build 69.5

The following platforms are not affected and do not require the firmware
update:

o MPX 5900 series

o MPX/SDX 8900 series

o MPX/SDX 15000-50G

o MPX/SDX 26000-50S series

o MPX/SDX 26000-100G series

o MPX/SDX 26000 series

o VPX

How to check your platform: https://docs.citrix.com/en-us/netscaler/12/ssl/
support-for-mpx-5900-8900-platforms.html


Mitigating Factors

Citrix ADC and NetScaler Gateway appliances that have disabled CBC-based cipher
suites are not affected by this vulnerability. Citrix also recommends
prioritizing GCM-based ciphers.


What Customers Should Do

This vulnerability has been addressed in the following versions of Citrix ADC
and NetScaler Gateway:

o Citrix ADC and NetScaler Gateway version 12.1 build 50.31 and later

o Citrix ADC and NetScaler Gateway version 12.0 build 60.9 and later

o Citrix ADC and NetScaler Gateway version 11.1 build 60.14 and later

o Citrix ADC and NetScaler Gateway version 11.0 build 72.17 and later 

o Citrix ADC and NetScaler Gateway version 10.5 build 69.5 and later


These new versions can be found on the Citrix website at the following
locations:

https://www.citrix.com/downloads/netscaler-adc/

https://www.citrix.com/downloads/netscaler-gateway/

Citrix recommends that affected customers apply appropriate mitigation or
upgrade all of their vulnerable Citrix ADC appliances to a version of the
appliance firmware that contains a fix for this issue as soon as possible.

Information on how to configure available cipher suites on Citrix ADC can be
found in the Citrix ADC documentation: https://docs.citrix.com/en-us/netscaler/
12-1/ssl/ciphers-available-on-the-citrix-adc-appliances


Acknowledgements

Citrix would like to thank the following for working with us to protect Citrix
customers:

o Craig Young of Tripwire VERT

o Janis Fliegenschmidt of Ruhr-Universitat Bochum

o Juraj Somorovsky of Ruhr-Universitat Bochum / Hackmanit GmbH

o Nimrod Aviram of Tel Aviv University

o Robert Merget of Ruhr-Universitat Bochum 


What Citrix Is Doing

Citrix is notifying customers and channel partners about this potential
security issue. This article is also available from the Citrix Knowledge Center
at  http://support.citrix.com/.


Obtaining Support on This Issue

If you require technical assistance with this issue, please contact Citrix
Technical Support. Contact details for Citrix Technical Support are available
at  https://www.citrix.com/support/open-a-support-case.html. 


Reporting Security Vulnerabilities

Citrix welcomes input regarding the security of its products and considers any
and all potential vulnerabilities seriously. For guidance on how to report
security-related issues to Citrix, please see the following document: CTX081743
- - Reporting Security Issues to Citrix


Changelog

+-------------------------------------+---------------------------------------+
|Date                                 |Change                                 |
+-------------------------------------+---------------------------------------+
|23rd January 2019                    |Initial Publishing                     |
+-------------------------------------+---------------------------------------+

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