Citrix ADC and Gateway Could Allow for Authentication Bypass

Fortify Security Team
Nov 10, 2022

Multiple vulnerabilities have been discovered in Citrix ADC and Gateway, the most severe of which could allow for Authentication Bypass. Citrix ADC and Gateway is an Application Delivery Controller and a gateway service to products respectively. Successful exploitation of the most severe of these vulnerabilities could result in Authentication Bypass. A malicious actor may be able to obtain administrative access. Depending on the permission associated with the application running the exploit, an attacker could then install programs; view, change, or delete data.

THREAT INTELLIGENCE: There are currently no reports of these vulnerabilities being exploited in the wild.

SYSTEMS AFFECTED:

  • ADC and Gateway 13.1
  • ADC and Gateway 13.0
  • ADC and Gateway 12.1
  • ADC 12.1 FIPS
  • ADC 12.1-NDcPP

RISK:
Government:

  • Large and medium government entities: High
  • Small government entities: Medium

Businesses:

  • Large and medium business entities: High
  • Small business entities: Medium

Home users: Low

TECHNICAL SUMMARY:

Multiple vulnerabilities have been discovered in Citrix ADC and Gateway, the most severe of which could allow for Authentication Bypass. Details of these vulnerabilities are as follows:
TacticInitial Access (TA0001):
TechniqueExternal Remote Services (T1133):

  • Authentication Bypass vulnerability (CVE-2022-27510)
  • Insufficient Verification of Data Authenticity Vulnerability (CVE-2022-27513)
  • Protection Mechanism Failure Vulnerability (CVE-2022-27516)

Successful exploitation of the most severe of these vulnerabilities could result in Authentication Bypass. A malicious actor may be able to obtain administrative access. Depending on the permission associated with the application running the exploit, an attacker could then install programs; view, change, or delete data.

RECOMMENDATIONS:

We recommend the following actions be taken:

  • Apply appropriate updates provided by Citrix to vulnerable systems immediately after appropriate testing. (M1051: Update Software)
    • Safeguard 7.1: Establish and Maintain a Vulnerability Management Process: Establish and maintain a documented vulnerability management process for enterprise assets. Review and update documentation annually, or when significant enterprise changes occur that could impact this Safeguard.
    • Safeguard 7.4: Perform Automated Application Patch Management: Perform application updates on enterprise assets through automated patch management on a monthly, or more frequent, basis.
    • Safeguard 7.7: Remediate Detected Vulnerabilities: Remediate detected vulnerabilities in software through processes and tooling on a monthly, or more frequent, basis, based on the remediation process.
    • Safeguard 9.1: Ensure Use of Only Fully Supported Browsers and Email Clients: Ensure only fully supported browsers and email clients are allowed to execute in the enterprise, only using the latest version of browsers and email clients provided through the vendor.
  • Apply the Principle of Least Privilege to all systems and services. Run all software as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack. (M1026: Privileged Account Management)
    • Safeguard 4.7: Manage Default Accounts on Enterprise Assets and Software: Manage default accounts on enterprise assets and software, such as root, administrator, and other pre-configured vendor accounts. Example implementations can include: disabling default accounts or making them unusable.
    • Safeguard 5.4: Restrict Administrator Privileges to Dedicated Administrator Accounts: Restrict administrator privileges to dedicated administrator accounts on enterprise assets. Conduct general computing activities, such as internet browsing, email, and productivity suite use, from the user’s primary, non-privileged account.
  • Restrict execution of code to a virtual environment on or in transit to an endpoint system. (M1048: Application Isolation and Sandboxing)
    • Safeguard 4.1:  Establish and Maintain a Secure Configuration Process:  Establish and maintain a secure configuration process for enterprise assets (end-user devices, including portable and mobile, non-computing/IoT devices, and servers) and software (operating systems and applications). Review and update documentation annually, or when significant enterprise changes occur that could impact this Safeguard.
    • Safeguard 16.8:  Separate Production and Non-Production Systems:  Maintain separate environments for production and non-production systems.
  • Use capabilities to detect and block conditions that may lead to or be indicative of a software exploit occurring. (M1050: Exploit Protection)
    • Safeguard 10.5:  Enable Anti-Exploitation Features: Enable anti-exploitation features on enterprise assets and software, where possible, such as Microsoft® Data Execution Prevention (DEP), Windows® Defender Exploit Guard (WDEG), or Apple® System Integrity Protection (SIP) and Gatekeeper™.
    • Safeguard 13.10:  Performing Application Layer Filtering:  Perform application layer filtering. Example implementations include a filtering proxy, application layer firewall, or gateway.
  • Restrict use of certain websites, block downloads/attachments, block Javascript, restrict browser extensions, etc. (M1021: Restrict Web-Based Content)
    • Safeguard 9.2: Use DNS Filtering Services: Use DNS filtering services on all enterprise assets to block access to known malicious domains.
    • Safeguard 9.3: Maintain and Enforce Network-Based URL Filters: Enforce and update network-based URL filters to limit an enterprise asset from connecting to potentially malicious or unapproved websites. Example implementations include category-based filtering, reputation-based filtering, or through the use of block lists. Enforce filters for all enterprise assets.
    • Safeguard 9.6: Block Unnecessary File Types: Block unnecessary file types attempting to enter the enterprise’s email gateway.
  • Inform and educate users regarding the threats posed by hypertext links contained in emails or attachments especially from un-trusted sources. Remind users not to visit un-trusted websites or follow links provided by unknown or un-trusted sources. (M1017: User Training)
    • Safeguard 14.1: Establish and Maintain a Security Awareness Program: Establish and maintain a security awareness program. The purpose of a security awareness program is to educate the enterprise’s workforce on how to interact with enterprise assets and data in a secure manner. Conduct training at hire and, at a minimum, annually. Review and update content annually, or when significant enterprise changes occur that could impact this Safeguard.
    • Safeguard 14.2: Train Workforce Members to Recognize Social Engineering Attacks: Train workforce members to recognize social engineering attacks, such as phishing, pre-texting, and tailgating.

REFERENCES:

Citrix:
https://support.citrix.com/article/CTX463706/citrix-gateway-and-citrix-adc-security-bulletin-for-cve202227510-cve202227513-and-cve202227516

CVE:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-27510
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-27513
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-27516

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