Vulnerabilities and Threats (Corvus Alerts)
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      Citrix Vulnerability Advisory | December 2022

      Citrix confirmed a critical vulnerability in Citrix Gateway and Citrix ADC products. Here's what you need to know.

      Background

      On December 13, 2022, Citrix released an advisory detailing a critical security flaw in Citrix Gateway and Citrix Application Delivery Controller (ADC). Citrix Gateway is commonly used as a remote access solution and Citrix ADC is a networking appliance for web applications. The security flaw (CVE-2022-27518) allows a remote, unauthenticated attacker to perform arbitrary code execution. Citrix reports that this vulnerability is being actively exploited by attackers. A security patch has been released and should be applied as soon as possible.

      The vulnerability affects the following products and versions:

      • Citrix ADC and Citrix Gateway 13.0 before 13.0-58.32 
      • Citrix ADC and Citrix Gateway 12.1 before 12.1-65.25 
      • Citrix ADC 12.1-FIPS before 12.1-55.291 
      • Citrix ADC 12.1-NDcPP before 12.1-55.291 

      Citrix ADC and Citrix Gateway version 13.1 is unaffected.

      For exploitation, the Citrix ADC or Citrix Gateway must be configured as a SAML SP or a SAML IdP. See instructions under “Next Steps” to determine if your appliance is configured as a SAML SP or a SAML IdP. If you are unable to determine, we recommend upgrading to the latest version out of caution.

      Impact

      Without a security patch, an unauthenticated remote attacker may be able to gain access to an affected Gateway or ADC appliance and execute arbitrary code. From there the attacker could move around the network and conduct further exploitation. Corvus has observed similar vulnerabilities lead to ransomware attacks.


      Note: This only applies to customer-managed Citrix ADC and Citrix Gateway appliances. Customers using Citrix-managed cloud services or Citrix-managed Adaptive Authentication do not need to take any action.

      Next steps for Citrix customers:

      1. Upgrade to a non-vulnerable version of ADC or Gateway as soon as possible:
        • Citrix ADC and Citrix Gateway 13.0-58.32 and later releases 
        • Citrix ADC and Citrix Gateway 12.1-65.25 and later releases of 12.1 
        • Citrix ADC 12.1-FIPS 12.1-55.291 and later releases of 12.1-FIPS  
        • Citrix ADC 12.1-NDcPP 12.1-55.291 and later releases of 12.1-NDcPP 
        Note: Please note that Citrix ADC and Citrix Gateway versions prior to 12.1 are EOL and customers on those versions are urged to upgrade to one of the supported versions.

      2. Customers can determine if their Citrix ADC or Citrix Gateway is configured as a SAML SP or a SAML IdP by inspecting the ns.conf file for the following commands: 

        Appliance is configured as a SAML SP
        add authentication samlAction

        Appliance is configured as a SAML IdP  
        add authentication samlIdPProfile
        If either of the commands are present in the ns.conf file and if the version is an affected version, then it is critical that the appliance be updated.

      3. If you require technical assistance with this issue, please contact Citrix Technical Support.

      Resources

      https://support.citrix.com/article/CTX47499