Multiple vulnerabilities have been discovered in FortiOS, the most severe of which could allow for remote code execution. FortiOS is Fortinet’s operating system used across many Fortinet devices. Successful exploitation of the most severe of these vulnerabilities could allow for remote code execution in the context of the system. Depending on the privileges associated with the service account, an attacker could then install programs; view, change, or delete data. Service accounts that are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.

Fortinet reports that CVE-2024-21762 is potentially being exploited in the wild.

Multiple vulnerabilities have been discovered in FortiOS, the most severe of which could allow for remote code execution. Details of these vulnerabilities are as follows
Tactic: Initial Access (TA0001):
Technique: Exploit Public-Facing Application (T1190):

• An out-of-bounds write vulnerability in FortiOS may allow a remote unauthenticated attacker to execute arbitrary code or commands via specially crafted HTTP requests. (CVE-2024-21762)
• A use of externally-controlled format string vulnerability in FortiOS fgfmd daemon may allow a remote unauthenticated attacker to execute arbitrary code or commands via specially crafted requests. (CVE-2024-23113)
  Details of lower-severity vulnerabilities are as follows:
• The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly. (CVE-2023-44487)
• An improper certificate validation vulnerability in FortiOS may allow an unauthenticated attacker in a Man-in-the-Middle position to decipher and alter the FortiLink communication channel between the FortiOS device and a FortiSwitch instance. (CVE-2023-47537)
  Successful exploitation of the most severe of these vulnerabilities could allow for remote code execution in the context of the system. Depending on the privileges associated with the service account, an attacker could then install programs; view, change, or delete data. Service accounts that are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.

We recommend the following actions be taken:

• Apply appropriate updates provided by Fortinet to vulnerable systems immediately after appropriate testing. (M1051: Update Software)
  o 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.
  o Safeguard 7.2: Establish and Maintain a Remediation Process: Establish and maintain a risk-based remediation strategy documented in a remediation process, with monthly, or more frequent, reviews.
  o 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.
  o Safeguard 7.5 : Perform Automated Vulnerability Scans of Internal Enterprise Assets: Perform automated vulnerability scans of internal enterprise assets on a quarterly, or more frequent, basis. Conduct both authenticated and unauthenticated scans, using a SCAP-compliant vulnerability scanning tool.
  o 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.
  o Safeguard 12.1: Ensure Network Infrastructure is Up-to-Date: Ensure network infrastructure is kept up-to-date. Example implementations include running the latest stable release of software and/or using currently supported network-as-a-service (NaaS) offerings. Review software versions monthly, or more frequently, to verify software support.
  o Safeguard 18.1: Establish and Maintain a Penetration Testing Program: Establish and maintain a penetration testing program appropriate to the size, complexity, and maturity of the enterprise. Penetration testing program characteristics include scope, such as network, web application, Application Programming Interface (API), hosted services, and physical premise controls; frequency; limitations, such as acceptable hours, and excluded attack types; point of contact information; remediation, such as how findings will be routed internally; and retrospective requirements.
  o Safeguard 18.2: Perform Periodic External Penetration Tests: Perform periodic external penetration tests based on program requirements, no less than annually. External penetration testing must include enterprise and environmental reconnaissance to detect exploitable information. Penetration testing requires specialized skills and experience and must be conducted through a qualified party. The testing may be clear box or opaque box.
  o Safeguard 18.3: Remediate Penetration Test Findings: Remediate penetration test findings based on the enterprise’s policy for remediation scope and prioritization.
• Vulnerability scanning is used to find potentially exploitable software vulnerabilities to remediate them. (M1016: Vulnerability Scanning)
  o Safeguard 16.13: Conduct Application Penetration Testing: Conduct application penetration testing. For critical applications, authenticated penetration testing is better suited to finding business logic vulnerabilities than code scanning and automated security testing. Penetration testing relies on the skill of the tester to manually manipulate an application as an authenticated and unauthenticated user.
• 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)
  o 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.
  o 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.
  o Safeguard 5.5: Establish and Maintain an Inventory of Service Accounts: Establish and maintain an inventory of service accounts. The inventory, at a minimum, must contain department owner, review date, and purpose. Perform service account reviews to validate that all active accounts are authorized, on a recurring schedule at a minimum quarterly, or more frequently
• Architect sections of the network to isolate critical systems, functions, or resources. Use physical and logical segmentation to prevent access to potentially sensitive systems and information. Use a DMZ to contain any internet-facing services that should not be exposed from the internal network. Configure separate virtual private cloud (VPC) instances to isolate critical cloud systems. (M1030: Network Segmentation)
  o Safeguard 12.2: Establish and Maintain a Secure Network Architecture: Establish and maintain a secure network architecture. A secure network architecture must address segmentation, least privilege, and availability, at a minimum.
• Use capabilities to detect and block conditions that may lead to or be indicative of a software exploit occurring. (M1050: Exploit Protection)
  o 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™.
• Restrict use of certain websites, block downloads/attachments, block Javascript, restrict browser extensions, etc. (M1021: Restrict Web-Based Content)
  o Safeguard 9.2: Use DNS Filtering Services: Use DNS filtering services on all enterprise assets to block access to known malicious domains.
  o 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.
  o Safeguard 9.6: Block Unnecessary File Types: Block unnecessary file types attempting to enter the enterprise’s email gateway.
• Remind users not to visit un-trusted websites or follow links provided by unknown or un-trusted sources. Inform and educate users regarding the threats posed by hypertext links contained in emails or attachments especially from un-trusted sources. (M1017: User Training)
  o 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.
  o 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.