CVE-2017-14187 in FortiOS
Summary
by MITRE
A local privilege escalation and local code execution vulnerability in Fortinet FortiOS 5.6.0 to 5.6.2, 5.4.0 to 5.4.8, and 5.2 and below versions allows attacker to execute unauthorized binary program contained on an USB drive plugged into a FortiGate via linking the aforementioned binary program to a command that is allowed to be run by the fnsysctl CLI command.
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Analysis
by VulDB Data Team • 02/25/2026
The vulnerability identified as CVE-2017-14187 represents a critical local privilege escalation flaw within Fortinet FortiOS operating systems affecting multiple version ranges including 5.6.0 to 5.6.2, 5.4.0 to 5.4.8, and versions 5.2 and below. This security weakness enables attackers to achieve unauthorized code execution through a sophisticated attack vector involving removable USB storage devices. The vulnerability specifically leverages the fnsysctl command line interface which, when improperly configured or secured, allows linking of malicious binary programs to commands that should otherwise be restricted. This flaw fundamentally compromises the integrity of the FortiGate device's security model by providing a pathway for local attackers to elevate their privileges beyond normal operational boundaries.
The technical implementation of this vulnerability stems from inadequate input validation and privilege separation mechanisms within the FortiOS command execution framework. When an attacker plugs a USB drive containing a malicious binary into a vulnerable FortiGate device, the system's failure to properly sanitize or restrict command execution paths allows the attacker to associate the malicious program with legitimate commands that are permitted to run through the fnsysctl interface. This creates an exploitable condition where the system's trust model is violated, enabling code execution with elevated privileges. The flaw operates at the system level where legitimate administrative commands are improperly separated from potentially malicious execution contexts, creating a dangerous overlap in command processing capabilities.
The operational impact of CVE-2017-14187 extends beyond simple privilege escalation to encompass full system compromise capabilities. An attacker exploiting this vulnerability can gain root-level access to the FortiGate device, effectively bypassing all network security controls and monitoring systems that the device is designed to provide. This represents a complete breakdown in the device's security architecture, as the attacker can manipulate system configurations, access sensitive network traffic, and potentially use the compromised device as a pivot point for further attacks within the network infrastructure. The vulnerability's local nature means that physical access to the device or the ability to execute code on the device's local network interface is sufficient for exploitation, making it particularly dangerous in environments where physical security controls may be insufficient.
Mitigation strategies for this vulnerability require immediate implementation of firmware updates to versions that address the privilege escalation flaw. Organizations should also implement strict physical security measures around FortiGate devices to prevent unauthorized USB insertion and ensure that only authorized personnel have access to the device's local interfaces. Network segmentation and monitoring should be enhanced to detect unusual command execution patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-284 which addresses improper access control, and represents a significant concern for ATT&CK technique T1059 which covers command and scripting interpreter usage. Security teams should also consider implementing automated patch management processes to ensure rapid deployment of security updates across all network infrastructure devices. Additionally, regular security assessments should verify that administrative interfaces are properly configured and that unnecessary command execution permissions have been revoked to minimize the attack surface available to potential exploiters.