Vulnerabilities have been identified in Citrix Virtual Apps and Desktops that could, if exploited, result in:
A user who has access to a Windows Virtual Desktop being able to escalate their privilege level on that Windows Virtual Desktop to SYSTEM.
Remote compromise of a Windows Virtual Desktop which has Windows file sharing (SMB) enabled.
These vulnerabilities have the following identifiers:
CVE ID
Description
Vulnerability Type
Pre-conditions
CVE-2020-8269
An unprivileged Windows user on the VDA can perform arbitrary command execution as SYSTEM
CWE-269: Improper Privilege Management
The attacker must be an authenticated user on the Windows VDA with write access to the C:\ directory
CVE-2020-8270
An unprivileged Windows user on the VDA or a SMB user can perform arbitrary command execution as SYSTEM
CWE-78: Improper Neutralization of Special Elements used in an OS Command (‹OS Command Injection›)
The attacker must be an authenticated user on the Windows VDA or be authenticated to Windows SMB service running on the VDA
The vulnerabilities affect the following supported versions of Citrix Virtual Apps and Desktops:
Citrix Virtual Apps and Desktops 2006 and earlier versions
Citrix Virtual Apps and Desktops 1912 LTSR CU1 and earlier versions of 1912 LTSR
Citrix XenApp / XenDesktop 7.15 LTSR CU6 and earlier versions of 7.15 LTSR
Citrix XenApp / XenDesktop 7.6 LTSR CU8 and earlier versions of 7.6 LTSR
Please note that Citrix XenApp / XenDesktop 7.6 LTSR is not affected by CVE-2020-8270.
Mitigating Factors
CVE-2020-8269 – This issue is only exploitable if low-privilege users have been granted permission to write files to the C:\ directory. This permission is not default in Windows and Citrix recommends that users are only granted the permissions they require.
CVE-2020-8270 – A remote compromise is only possible when Windows file sharing (SMB) is enabled on the Windows Virtual Desktop. If authentication is required for SMB then an attacker must also be able to authenticate in order to remotely compromise the Virtual Desktop.
What Customers Should Do
The issues have been addressed in the following versions of Citrix Virtual Apps and Desktops:
Citrix Virtual Apps and Desktops 2009 or later
Citrix Virtual Apps and Desktops 1912 LTSR CU1 hotfixes CTX285870, CTX285871, CTX285872 and CTX286120, and later cumulative updates
Citrix XenApp / XenDesktop 7.15 LTSR CU6 hotfixes CTX285341, CTX285342 and CTX285344, and later cumulative updates
Citrix XenApp / XenDesktop 7.6 LTSR CU9 and later cumulative updates
Citrix strongly recommends that customers upgrade to a fixed version as soon as possible.
The latest versions of Citrix Virtual Apps and Desktops are available from the following location:
Hotfixes to address the issues in Citrix Virtual Apps and Desktops 1912 LTSR and Citrix XenApp / XenDesktop 7.15 LTSR can be downloaded from the following locations:
Customers should ensure they have installed the latest cumulative update and then apply all hotfixes for that version.
Acknowledgements
Citrix would like to thank Hannay Al-Mohanna of F-Secure Consulting and Michael Garrison of State Farm Information Security for working with us to protect Citrix customers.
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/.
Vulnerabilities have been identified in Citrix Gateway Plug-in for Windows that, if exploited, could result in a local user escalating their privilege level to SYSTEM.
The vulnerabilities have the following identifiers:
CVE-2020-8257
CVE-2020-8258
These vulnerabilities affect the following supported versions of Citrix Gateway Plug-in for Windows:
Customers with Citrix ADC or Citrix Gateway:
Citrix Gateway Plug-in 13.0 for Windows before 64.35
Citrix Gateway Plug-in 12.1 for Windows before 59.16
These vulnerabilities do not affect Citrix Gateway Plug-in on other platforms.
Citrix Gateway Plug-in for Windows 11.1 is not affected by these vulnerabilities. Other versions are now End-of-Life and no longer supported.
The following supported versions of Citrix ADC (formerly known as NetScaler ADC) and Citrix Gateway (formerly known as NetScaler Gateway) include an impacted version of Citrix Gateway Plug-in in order to distribute it to users when they connect to Citrix Gateway:
Citrix ADC and Citrix Gateway 13.0 before 64.35
NetScaler ADC and NetScaler Gateway 12.1 before 59.16
Citrix ADC 12.1-FIPS before 55.190
The issues have been addressed in the following versions of Citrix Gateway Plug-in for Windows:
Customers with Citrix ADC or Citrix Gateway:
Citrix Gateway Plug-in 13.0 for Windows 64.35 and later versions
Citrix Gateway Plug-in 12.1 for Windows 59.16 and later versions
The latest versions of Citrix Gateway Plug-in for Windows are available from:
Mehrere Schwachstellen wurden in Citrix ADC (früher bekannt als NetScaler ADC), Citrix Gateway (früher bekannt als NetScaler Gateway) und Citrix SD-WAN WANOP Appliance-Modelle 4000-WO, 4100-WO, 5000-WO und 5100-WO entdeckt. Diese Schwachstellen können, wenn sie ausgenutzt werden, zu den folgenden Sicherheitsproblemen führen:
CVE ID
Description
Vulnerability Type
Affected Products
Pre-conditions
CVE-2020-8245
An HTML Injection attack against the SSL VPN web portal
CWE-79: Improper Neutralization of Input During Web Page Generation
Citrix ADC, Citrix Gateway
Requires an authenticated victim on the SSL VPN web portal who must open an attacker-controlled link in the browser
CVE-2020-8246
A denial of service attack originating from the management network
CWE-400: Uncontrolled Resource Consumption
Citrix ADC, Citrix Gateway, Citrix SDWAN WAN-OP
Unauthenticated attacker with access to the management network
CVE-2020-8247
Escalation of privileges on the management interface
CWE-269: Improper Privilege Management
Citrix ADC, Citrix Gateway, Citrix SDWAN WAN-OP
An attacker must possess privilege to execute arbitrary commands on the management interface
Die Schwachstellen werden in den folgenden unterstützten Versionen behoben:
Citrix ADC and Citrix Gateway 13.0-64.35 and later releases
Citrix ADC and NetScaler Gateway 12.1-58.15 and later releases
Citrix ADC 12.1-FIPS 12.1-55.187 and later releases
Citrix ADC and NetScaler Gateway 11.1-65.12 and later releases
Citrix SD-WAN WANOP 11.2.1a and later releases
Citrix SD-WAN WANOP 11.1.2a and later releases
Citrix SD-WAN WANOP 11.0.3f and later releases
Citrix SD-WAN WANOP 10.2.7b and later releases
Zusätzlich wurden den oben genannten Versionen von Citrix ADC, Citrix Gateway und Citrix SD-WAN WANOP Sicherheitsverbesserungen hinzugefügt, um Kunden vor Angriffen durch HTTP Request Smuggling zu schützen. Kunden können diese Verbesserungen über die Verwaltungsschnittstelle von Citrix ADC aktivieren. Weitere Informationen finden Sie unter https://support.citrix.com/article/CTX282268.
Mildernde Faktoren
Zwei der drei Schwachstellen haben ihren Ursprung in der Verwaltungsschnittstelle von Citrix ADC, Citrix Gateway und Citrix SD-WAN WANOP. Citrix empfiehlt dringend, den Netzwerkverkehr zur Verwaltungsschnittstelle der Appliance entweder physisch oder logisch vom normalen Netzwerkverkehr zu trennen. Auf diese Weise wird das Risiko der Ausnutzung stark vermindert. Weitere Informationen finden Sie unter https://docs.citrix.com/en-us/citrix-adc/citrix-adc-secure-deployment/secure-deployment-guide.html.
Problemlösung
Installieren Sie so schnell wie möglich ein der veröffentlichten Updates.
Haben Sie Fragen oder benötigen Hilfe? Kontaktieren Sie uns, wir helfen Ihnen gerne weiter.
Citrix beschreibt in einem Knowledge Base Artikel, dass alle Workspace App und Receiver Versionen vor 1912 von zwei Sicherheitslücken betroffen sind. Mit diesen kann sich ein Angreifer erhöhte Rechte geben und so das lokale System übernehmen.
Im Folgenden werden diese beiden Lücken genauer beschrieben:
CVE-2020-13884:Citrix Workspace App before 2006.1 on Windows has Insecure Permissions for %PROGRAMDATA%\Citrix (and an unquoted UninstallString), which allows local users to gain privileges by copying a malicious citrix.exe there.
CVE-2020-13885: Citrix Workspace App before 2006.1 on Windows has Insecure Permissions for «%PROGRAMDATA%\Citrix\Citrix Workspace ####\» which allows local users to gain privileges by copying a malicious webio.dll there.
Diese Schwachstellen betreffen nur Windows Clients.
