Fortinet CVE-2023-42788: OS Command Injection Vulnerability

Fortinet Zero-Day Patch

Fortinet, a globally trusted provider of cybersecurity infrastructure, recently issued an update confirming that a serious security vulnerability, CVE-2023-42788, affects not only FortiManager and FortiAnalyzer, but also their cloud-based counterpart, FortiAnalyzer-Cloud. This vulnerability, categorized as an OS command injection issue (CWE-78), presents a real risk of unauthorized code execution even by low-privileged local attackers.
We look at an overview of the vulnerability, its implications, and detailed steps for mitigation.

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What is CVE-2023-42788

CVE-2023-42788 stems from an improper neutralization of special elements in OS commands within Fortinet’s command-line interface (CLI). Attackers with local access and minimal privileges can craft malicious inputs to exploit this flaw, effectively injecting and executing unauthorized commands.

Discovered by Loïc Restoux of Orange Innovation and reported through Orange CERT-CC, this vulnerability underscores persistent risks in CLI handling, especially given its connection to a previously identified issue, CVE-2021-26104, which had an incomplete patch.

Impacted Fortinet Products

  • FortiManager

  • FortiAnalyzer

  • FortiAnalyzer-Cloud

These tools are widely used in enterprise environments for centralized management, analytics, and network monitoring, making any compromise particularly severe.

Security Implications

The severity of CVE-2023-42788 lies in the following risks:

  • Privilege escalation from low-privileged user accounts

  • Remote code execution via internal compromise

  • Persistence installation and network pivoting

  • Disruption of centralized security analytics

In environments where Fortinet devices serve as the backbone for managing security events, any breach could render the entire setup blind to malicious activities.

Possible Solutions

To reduce the risk posed by CVE-2023-42788, organizations are strongly advised to take the following actions:

  1. Apply Fortinet Patches Immediately
    Visit the Fortinet Product Security Incident Response Team (PSIRT) page for the latest firmware updates and apply them to all affected products.

  2. Limit Local CLI Access
    Restrict CLI access to trusted administrative accounts. Remove or disable local accounts with unnecessary access, especially those with limited roles.

  3. Implement Least Privilege Principles
    Enforce access controls to ensure users only have the minimum permissions necessary. Avoid giving CLI-level access unless absolutely necessary.

  4. Monitor Logs and CLI Command Usage
    Regularly inspect logs for suspicious command executions. Set up alerts for unexpected or unapproved CLI usage.

  5. Isolate Critical Management Interfaces
    Use VLANs, firewall rules, or VPN tunnels to isolate management tools like FortiManager and FortiAnalyzer from broader network access.

  6. Review Past Fixes and Test Thoroughly
    Since this vulnerability is a continuation of a previous CVE, ensure prior patches (e.g., for CVE-2021-26104) were applied correctly and verified in testing environments.

Conclusion

CVE-2023-42788 is a stark reminder of the complexity of securing CLI interfaces and the consequences of incomplete patches. Fortinet users should act swiftly to apply the latest fixes, review access permissions, and reinforce their monitoring strategies. As always, staying proactive is key to defending against increasingly sophisticated threats.


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