CVE-2018-6435 in Fabric OS
Summary
by MITRE
A Vulnerability in the secryptocfg 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, and gain root access.
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Analysis
by VulDB Data Team • 04/11/2020
The vulnerability identified as CVE-2018-6435 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 secryptocfg command 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 level access. This represents a fundamental failure in the privilege separation mechanisms that should protect the underlying operating system from unauthorized administrative access.
The technical implementation of this vulnerability stems from improper input validation and insufficient sandboxing within the secryptocfg command execution environment. When users execute this command within the restricted shell, the system fails to properly sanitize or validate command arguments, allowing malicious input sequences to manipulate the execution flow. This vulnerability directly maps to CWE-20, which describes improper input validation in software systems, and CWE-264, which addresses permissions, privileges, and access controls. The restricted shell mechanism intended to contain user commands and prevent access to sensitive system functions becomes ineffective due to this flaw, creating a pathway for attackers to execute arbitrary commands with elevated privileges.
The operational impact of CVE-2018-6435 is severe and far-reaching within network infrastructure environments that utilize Brocade Fabric OS switches. Local attackers who can access the command line interface with standard user credentials can immediately escalate their privileges to root access, gaining complete control over the switch's operational functions. This includes the ability to modify network configurations, access sensitive data stored on the switch, manipulate routing tables, and potentially disrupt network services. The vulnerability affects the core security model of the device, undermining the trust model that network administrators rely upon to maintain secure network operations. Attackers can leverage this privilege escalation to establish persistent access points, create backdoors, or exfiltrate network configuration data that could compromise the entire network infrastructure.
Organizations utilizing affected Brocade Fabric OS versions should implement immediate mitigations including upgrading to patched versions 8.2.1, 8.1.2f, 8.0.2f, or 7.4.2d respectively. Network administrators should also consider implementing additional security controls such as disabling unnecessary command access, implementing strict access controls for CLI interfaces, and monitoring for unusual command execution patterns. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting T1068 which describes "Exploitation for Privilege Escalation" and T1548 which addresses "Abuse of Functionality." Organizations should also review their network access controls and implement principle of least privilege models to limit the potential impact of such vulnerabilities. The vulnerability demonstrates the critical importance of proper sandboxing and input validation in restricted shell environments, as outlined in the OWASP Top 10 security principles, particularly focusing on secure coding practices and privilege management controls.