CERT mailing list archives

AA20-020A: Critical Vulnerability in Citrix Application Delivery Controller, Gateway, and SD-WAN WANOP

From: "US-CERT" <US-CERT () ncas us-cert gov>
Date: Fri, 24 Jan 2020 15:21:58 -0600
Cybersecurity and Infrastructure Security Agency Logo

National Cyber Awareness System:



AA20-020A: Critical Vulnerability in Citrix Application Delivery Controller, Gateway, and SD-WAN WANOP [ 
https://www.us-cert.gov/ncas/alerts/aa20-020a ] 01/20/2020 09:54 AM EST 
Original release date: January 20, 2020 | Last revised: January 24, 2020

Summary

"Note: As of January 24, 2020, Citrix has released all expected updates in response to CVE-2019-19781."[1] [ 
https://www.citrix.com/blogs/2020/01/24/citrix-releases-final-fixes-for-cve-2019-19781/ ]

On January 19, 2020, Citrix releasedfirmware updates for Citrix Application Delivery Controller (ADC) and Citrix 
Gateway versions 11.1 and 12.0.
On January 22, 2020,Citrix released security updates for vulnerable SD-WAN WANOP appliances.
On January 23, 2020, Citrixreleased firmware updates forCitrix ADC and Gateway versions 12.1 and 13.0.
On January 24, 2020, Citrix released firmware updates for Citrix ADC and Gateway version 10.5.

A remote, unauthenticated attacker could exploit CVE-2019-19781 to perform arbitrary code execution.[2] [ 
https://support.citrix.com/article/CTX267027 ] This vulnerability has been detected in exploits in the wild.[3] [ 
https://www.ncsc.gov.uk/news/citrix-alert ]

The Cybersecurity and Infrastructure Agency (CISA) strongly recommends that all users and administrators upgrade their 
vulnerable appliances as soon as possible.

Timeline of Specific Events

  * December 17, 2019  Citrix released Security Bulletin CTX267027 with mitigations steps. 
  * January 8, 2020  The CERT Coordination Center (CERT/CC) released Vulnerability Note VU#619785: Citrix Application 
Delivery Controller and Citrix Gateway Web Server Vulnerability,[4] [ https://www.kb.cert.org/vuls/id/619785/ ] and 
CISA releases a Current Activity entry.[5] [ 
https://www.us-cert.gov/ncas/current-activity/2020/01/08/citrix-application-delivery-controller-and-citrix-gateway ] 
  * January 10, 2020  The National Security Agency (NSA) released a Cybersecurity Advisory on CVE-2019-19781.[6] [ 
https://media.defense.gov/2020/Jan/10/2002233132/-1/-1/0/CSA%20FOR%20CITRIXADCANDCITRIXGATEWAY_20200109.PDF ] 
  * January 11, 2020  Citrix released blog post on CVE-2019-19781 with timeline for fixes.[7] [ 
https://www.citrix.com/blogs/2020/01/11/citrix-provides-update-on-citrix-adc-citrix-gateway-vulnerability/ ] 
  * January 13, 2020  CISA released a Current Activity entry describing their utility that enables users and 
administrators to test whether their Citrix ADC and Citrix Gateway firmware is susceptible to the CVE-2019-19781 
vulnerability.[8] [ 
https://www.us-cert.gov/ncas/current-activity/2020/01/13/cisa-releases-test-citrix-adc-and-gateway-vulnerability ] 
  * January 16, 2020  Citrix announced that Citrix SD-WAN WANOP appliance is also vulnerable to CVE-2019-19781. 
  * January 19, 2020  Citrix released firmware updates for Citrix ADC and Citrix Gateway versions 11.1 and 12.0 and 
blog post on accelerated schedule for fixes.[9] [ 
https://www.citrix.com/blogs/2020/01/19/vulnerability-update-first-permanent-fixes-available-timeline-accelerated/ ] 
  * January 22, 2020  Citrix released security updates for Citrix SD-WAN WANOP release 10.2.6 and 11.0.3.[10] [ 
https://www.citrix.com/blogs/2020/01/22/update-on-cve-2019-19781-fixes-now-available-for-citrix-sd-wan-wanop/ ] 
  * January 22, 2020  Citrix and FireEye Mandiant released an indicator of compromise (IOC) scanning tool for 
CVE-2019-19781.[11] [ 
https://www.citrix.com/blogs/2020/01/22/citrix-and-fireeye-mandiant-share-forensic-tool-for-cve-2019-19781/ ] 
  * January 23, 2020  Citrix released firmware updates for Citrix ADC and Citrix Gateway versions 12.1 and 13.0.[12] [ 
https://www.citrix.com/blogs/2020/01/23/fixes-now-available-for-citrix-adc-citrix-gateway-versions-12-1-and-13-0/ ] 
  * January 24, 2020  Citrixreleased firmware updates for Citrix ADC and Citrix Gateway version 10.5. 

Technical Details

Impact

On December 17, 2019, Citrix reported vulnerability CVE-2019-19781. A remote, unauthenticated attacker could exploit 
this vulnerability to perform arbitrary code execution. This vulnerability has been detected in exploits in the wild.

The vulnerability affects the following appliances:


  * Citrix NetScaler ADC and NetScaler Gateway version 10.5  all supported builds 
  * Citrix ADC and NetScaler Gateway version 11.1  all supported builds before 11.1.63.15 
  * Citrix ADC and NetScaler Gateway version 12.0  all supported builds before 12.0.63.13 
  * Citrix ADC and NetScaler Gateway version 12.1  all supported builds before 12.1.55.18 
  * Citrix ADC and Citrix Gateway version 13.0  all supported builds before 13.0.47.24 
  * Citrix SD-WAN WANOP appliance models 4000-WO, 4100-WO, 5000-WO, and 5100-WO all supported software release builds 
before 10.2.6b and 11.0.3b. (Citrix SD-WAN WANOP is vulnerable because it packages Citrix ADC as a load balancer). 

Detection Measures

Citrix and FireEye Mandiant released an IOC scanning tool for CVE-2019-19781 [ 
https://github.com/citrix/ioc-scanner-CVE-2019-19781/ ] on January 22, 2020. The tool aids customers with detecting 
potential IOCs based on known attacks and exploits.[13] [ 
https://www.citrix.com/blogs/2020/01/22/citrix-and-fireeye-mandiant-share-forensic-tool-for-cve-2019-19781/ ]

See the National Security Agencys Cybersecurity Advisory on CVE-2020-19781 for other detection measures.[14] [ 
https://media.defense.gov/2020/Jan/10/2002233132/-1/-1/0/CSA%20FOR%20CITRIXADCANDCITRIXGATEWAY_20200109.PDF ]

CISA released a utility that enables users and administrators to detect whether their Citrix ADC and Citrix Gateway 
firmware is susceptible to CVE-2019-19781.[15]  [ 
https://www.us-cert.gov/ncas/current-activity/2020/01/13/cisa-releases-test-citrix-adc-and-gateway-vulnerability ]CISA 
encourages administrators to visit CISAs GitHub page [ https://github.com/cisagov/check-cve-2019-19781 ] to download 
and run the tool.

Mitigations

CISA strongly recommends users and administrators update Citrix ADC, Citrix Gateway, and Citrix SD-WAN WANOP as soon as 
possible.

The fixed builds can be downloaded from Citrix Downloads pages for Citrix ADC [ 
https://www.citrix.com/downloads/citrix-adc/ ], Citrix Gateway [ https://www.citrix.com/downloads/citrix-gateway/ ], 
and Citrix SD-WAN [ https://www.citrix.com/downloads/citrix-sd-wan/ ].

Until the appropriate update is implemented, users and administrators should apply Citrixs interim mitigation steps for 
CVE-2019-19781.[16] [ https://support.citrix.com/article/CTX267679 ] Verify the successful application of the above 
mitigations by using the tool in CTX269180  CVE-2019-19781  Verification ToolTest [ 
https://support.citrix.com/article/CTX269180 ].* Note:* these mitigation steps apply to Citrix ADC and SD-WAN WANOP 
deployments.[17] [ https://support.citrix.com/article/CTX267027 ]

Refer to table 1 for Citrixs planned fix schedule.[18] [ https://support.citrix.com/article/CTX267027 ]

*Table 1. Fix schedule for Citrix appliances vulnerable to CVE-2019-19781*

*Vulnerable Appliance* *Firmware Update* *Release Date* Citrix ADC and Citrix Gateway version 10.5 Refresh Build 
10.5.70.12 January 24, 2020 Citrix ADC and Citrix Gateway version 11.1 Refresh Build 11.1.63.15 January 19, 2020 Citrix 
ADC and Citrix Gateway version 12.0 Refresh Build 12.0.63.13 January 19, 2020 Citrix ADC and Citrix Gateway version 
12.1 Refresh Build  12.1.55.18 January 23, 2020 Citrix ADC and Citrix Gateway version 13.0 Refresh Build 13.0.47.24 
January 23, 2020 Citrix SD-WAN WANOP Release 10.2.6 Build 10.2.6b January 22, 2020 Citrix SD-WAN WANOP Release 11.0.3 
Build 11.0.3b January 22, 2020 



Administrators should review NSAs Citrix Advisory [ 
https://media.defense.gov/2020/Jan/10/2002233132/-1/-1/0/CSA%20FOR%20CITRIXADCANDCITRIXGATEWAY_20200109.PDF ] for other 
mitigations, such as applying the following defense-in-depth strategy:

Consider deploying a VPN capability using standardized protocols, preferably ones listed on the National Information 
Assurance Partnership (NIAP) Product Compliant List (PCL), in front of publicly accessible Citrix ADC and Citrix 
Gateway appliances to require user authentication for the VPN before being able to reach these appliances. Use of a 
proprietary SSLVPN/TLSVPN is discouraged.

References

  * [1] Citrix blog: Citrix releases final fixes for CVE-2019-19781 [ 
https://www.citrix.com/blogs/2020/01/24/citrix-releases-final-fixes-for-cve-2019-19781/ ] 
  * [2] Citrix Security Bulletin CTX267027, Vulnerability in Citrix Application Delivery Controller and Citrix Gateway  
[ https://support.citrix.com/article/CTX267027 ] 
  * [3] United Kingdom National Cyber Secrity Centre (NCSC) Alert: Actors exploiting Citrix products vulnerability  [ 
https://www.ncsc.gov.uk/news/citrix-alert ] 
  * [4] CERT/CC Vulnerability Note VU#619785  [ https://www.kb.cert.org/vuls/id/619785/ ] 
  * [5] CISA Current Activity: Citrix Application Delivery Controller and Citrix Gateway Vulnerability  [ 
https://www.us-cert.gov/ncas/current-activity/2020/01/08/citrix-application-delivery-controller-and-citrix-gateway ] 
  * [6] NSA Cybersecurity Advisory: Mitigate CVE-2019-19781: Critical Vulnerability in Citrix Application Delivery 
Controller (ADC) and Citrix Gateway  [ 
https://media.defense.gov/2020/Jan/10/2002233132/-1/-1/0/CSA%20FOR%20CITRIXADCANDCITRIXGATEWAY_20200109.PDF ] 
  * [7] Citrix blog: Citrix provides update on Citrix ADC, Citrix Gateway vulnerability  [ 
https://www.citrix.com/blogs/2020/01/11/citrix-provides-update-on-citrix-adc-citrix-gateway-vulnerability/ ] 
  * [8] CISA Current Activity: CISA Releases Test for Citrix ADC and Gateway Vulnerability GitHub: CISAgov  
check-cve-2019-19781  [ 
https://www.us-cert.gov/ncas/current-activity/2020/01/13/cisa-releases-test-citrix-adc-and-gateway-vulnerability ] 
  * [9] Citrix Blog: Vulnerability Update: First permanent fixes available, timeline accelerated  [ 
https://www.citrix.com/blogs/2020/01/19/vulnerability-update-first-permanent-fixes-available-timeline-accelerated/ ] 
  * [10] Citrix Blog: Update on CVE-2019-19781: Fixes now available for Citrix SD-WAN WANOP [ 
https://www.citrix.com/blogs/2020/01/22/update-on-cve-2019-19781-fixes-now-available-for-citrix-sd-wan-wanop/ ] 
  * [11] Citrix Blog: Citrix and FireEye Mandiant share forensic tool for CVE-2019-19781 [ 
https://www.citrix.com/blogs/2020/01/22/citrix-and-fireeye-mandiant-share-forensic-tool-for-cve-2019-19781/ ] 
  * [12] Citrix Blog: Fixes now available for Citrix ADC, Citrix Gateway versions 12.1 and 13.0 [ 
https://www.citrix.com/blogs/2020/01/23/fixes-now-available-for-citrix-adc-citrix-gateway-versions-12-1-and-13-0/ ] 
  * [13] Citrix Blog: Citrix and FireEye Mandiant share forensic tool for CVE-2019-19781 [ 
https://www.citrix.com/blogs/2020/01/22/citrix-and-fireeye-mandiant-share-forensic-tool-for-cve-2019-19781/ ] 
  * [14] NSA Cybersecurity Advisory: Mitigate CVE-2019-19781: Critical Vulnerability in Citrix Application Delivery 
Controller (ADC) and Citrix Gateway  [ 
https://media.defense.gov/2020/Jan/10/2002233132/-1/-1/0/CSA%20FOR%20CITRIXADCANDCITRIXGATEWAY_20200109.PDF ] 
  * [15] CISA Current Activity: CISA Releases Test for Citrix ADC and Gateway Vulnerability GitHub: CISAgov  
check-cve-2019-19781  [ 
https://www.us-cert.gov/ncas/current-activity/2020/01/13/cisa-releases-test-citrix-adc-and-gateway-vulnerability ] 
  * [16] Citrix Security Bulletin CTX267679, Mitigation Steps for CVE-2019-19781  [ 
https://support.citrix.com/article/CTX267679 ] 
  * [17] Citrix Security Bulletin CTX267027, Vulnerability in Citrix Application Delivery Controller and Citrix Gateway 
 [ https://support.citrix.com/article/CTX267027 ] 
  * [18] Citrix Security Bulletin CTX267027, Vulnerability in Citrix Application Delivery Controller and Citrix Gateway 
 [ https://support.citrix.com/article/CTX267027 ] 

Revisions

  * January 20, 2020: Initial Version 
  * January 23, 2020: Updated with information about Citrix releasing fixes for SD-WAN WANOP appliances and an IOC 
scanning tool 
  * January 24, 2020: Updated with information about Citrix releasing fixes for Citrix ADC and Gateway versions 10.5, 
12.1, and 13.0 
________________________________________________________________________

This product is provided subject to this Notification [ https://www.us-cert.gov/privacy/notification ] and this Privacy 
& Use [ https://www.dhs.gov/privacy-policy ] policy.

body { font-size: 1em; font-family: Arial, Verdana, sans-serif; font-weight: normal; font-style: normal; color: 
#333333; } ________________________________________________________________________

A copy of this publication is available at www.us-cert.gov [ https://www.us-cert.gov ]. If you need help or have 
questions, please send an email to info () us-cert gov. Do not reply to this message since this email was sent from a 
notification-only address that is not monitored. To ensure you receive future US-CERT products, please add US-CERT () 
ncas us-cert gov to your address book. 

OTHER RESOURCES: Contact Us [ http://www.us-cert.gov/contact-us/ ] | Security Publications [ 
http://www.us-cert.gov/security-publications ] | Alerts and Tips [ http://www.us-cert.gov/ncas ] | Related Resources [ 
http://www.us-cert.gov/related-resources ]  

STAY CONNECTED: Sign up for email updates [ http://public.govdelivery.com/accounts/USDHSUSCERT/subscriber/new ]
Current thread:

AA20-020A: Critical Vulnerability in Citrix Application Delivery Controller, Gateway, and SD-WAN WANOP US-CERT (Jan 20)
- <Possible follow-ups>
- AA20-020A: Critical Vulnerability in Citrix Application Delivery Controller, Gateway, and SD-WAN WANOP US-CERT (Jan 24)