CVE-2018-9191 in FortiClient
Summary
by MITRE
A local privilege escalation in Fortinet FortiClient for Windows 6.0.4 and earlier allows attackers to execute unauthorized code or commands via the named pipe responsible for Forticlient updates.
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Analysis
by VulDB Data Team • 06/17/2020
The vulnerability identified as CVE-2018-9191 represents a critical local privilege escalation flaw within Fortinet FortiClient for Windows versions 6.0.4 and earlier. This security weakness specifically targets the named pipe mechanism that FortiClient employs for handling software updates, creating an avenue for malicious actors to elevate their privileges from standard user level to system administrator level. The vulnerability stems from inadequate access controls and privilege validation within the update process, allowing unauthorized code execution through the compromised named pipe interface.
The technical implementation of this flaw involves the improper handling of named pipe permissions within the FortiClient update service. When the FortiClient service attempts to communicate with the update mechanism through a named pipe, it fails to properly validate the privileges of connecting processes. This design flaw enables local attackers who can establish connections to the named pipe to inject malicious code that executes with elevated privileges. The vulnerability operates at the operating system level, leveraging Windows named pipe security mechanisms that should normally restrict access to privileged operations but are bypassed due to insufficient permission checks.
From an operational impact perspective, this vulnerability poses significant risks to enterprise environments where FortiClient is deployed. Attackers exploiting this weakness can gain full system control without requiring any network access or authentication credentials, making it particularly dangerous in scenarios where users may have legitimate access to systems. The privilege escalation allows malicious actors to install rootkits, modify system files, access sensitive data, and establish persistent backdoors. This vulnerability directly aligns with attack patterns documented in the MITRE ATT&CK framework under privilege escalation techniques, specifically targeting the 'Windows Admin Shares' and 'Service Execution' tactics.
Organizations utilizing FortiClient versions prior to 6.0.5 should immediately implement mitigations including applying the vendor-provided security patches, implementing network segmentation to limit local access to affected systems, and monitoring for unauthorized named pipe connections. The vulnerability also highlights the importance of principle of least privilege enforcement and proper access control implementation as outlined in CWE-276, which addresses improper permissions for critical resources. Security teams should conduct comprehensive vulnerability assessments to identify all affected systems and implement additional monitoring controls around named pipe usage and update service operations. Additionally, system administrators should review and tighten the security configuration of FortiClient services to prevent unauthorized access to update mechanisms and ensure that only authorized processes can communicate with the named pipe interfaces.