CVE-2018-6438 in Fabric OS
Summary
by MITRE
A Vulnerability in the supportsave command of Brocade Fabric OS command line interface (CLI) versions before 8.2.1, 8.1.2f, 8.0.2f, 7.4.2d could allow a local attacker to escape the restricted shell and, gain root access.
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Analysis
by VulDB Data Team • 04/11/2020
The vulnerability identified as CVE-2018-6438 represents a critical privilege escalation flaw within the Brocade Fabric OS command line interface that affects multiple version branches including 8.2.1, 8.1.2f, 8.0.2f, and 7.4.2d. This security weakness resides in the supportsave command functionality which operates within the restricted shell environment designed to limit user privileges and prevent unauthorized system access. The flaw enables local attackers with basic user credentials to bypass the intended security boundaries of the restricted shell and escalate their privileges to root access level, fundamentally compromising the system's security posture.
The technical implementation of this vulnerability stems from inadequate input validation and privilege handling within the supportsave command execution flow. When a local user executes the supportsave command, the system fails to properly sanitize or validate the command arguments, allowing malicious input to manipulate the execution context. This flaw specifically relates to command injection vulnerabilities and improper privilege separation mechanisms that should prevent non-root users from accessing system-level functions. The vulnerability manifests through a combination of insufficient access controls and inadequate sandboxing of CLI commands, creating an exploitable path that bypasses the normal privilege escalation restrictions imposed by the restricted shell environment.
Operationally, this vulnerability presents a severe risk to network infrastructure security as it allows any authenticated local user to gain complete system control without requiring additional authentication factors or elevated privileges. The impact extends beyond simple privilege escalation to encompass full system compromise, including potential data exfiltration, system modification, and network disruption capabilities. Attackers could leverage this vulnerability to establish persistent access points, modify network configurations, or deploy malicious payloads that could affect the entire fabric network. The restricted shell environment, which is specifically designed to prevent unauthorized access to critical system functions, becomes completely ineffective against this flaw, rendering the fundamental security model of the system vulnerable.
Organizations utilizing Brocade Fabric OS versions affected by CVE-2018-6438 should implement immediate mitigations including applying the vendor-provided patches and updates that address the privilege escalation vulnerability. System administrators should also consider implementing additional security controls such as monitoring for unusual supportsave command usage patterns and restricting local user access where possible. The vulnerability aligns with CWE-20 (Improper Input Validation) and CWE-269 (Improper Privilege Management) categories, and represents a significant concern under ATT&CK framework's privilege escalation techniques where local users can gain root access through command injection and shell escape methods. Regular security assessments and network segmentation strategies should be employed to minimize the potential impact of such vulnerabilities in production environments.