CVE-2018-6437 in Fabric OS
Summary
by MITRE
A Vulnerability in the help 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-2018-6437 resides within the help command functionality of Brocade Fabric OS command line interface across multiple affected versions including those before 8.2.1, 8.1.2f, 8.0.2f, and 7.4.2d. This represents a critical privilege escalation flaw that fundamentally undermines the security model of the network fabric operating system. The issue manifests as a command injection vulnerability that specifically targets the restricted shell environment designed to limit user capabilities and prevent unauthorized access to system resources. The vulnerability stems from insufficient input validation and sanitization within the help command implementation, creating a pathway for maliciously crafted input to bypass security controls and execute arbitrary commands with elevated privileges.
This vulnerability operates through a command injection mechanism that exploits the way the help command processes user input and generates responses. When a user interacts with the help system, the system fails to properly validate or sanitize the input parameters, allowing an attacker to inject malicious commands that get executed within the context of the shell. The restricted shell environment, which is intended to limit users to specific administrative functions while preventing access to system-level commands, becomes effectively useless when this vulnerability is exploited. The flaw enables a local attacker to escalate privileges from a regular user account to root access, effectively compromising the entire fabric switch and potentially the broader network infrastructure. This represents a classic example of a privilege escalation vulnerability that directly violates the principle of least privilege and undermines the security architecture of the network fabric.
The operational impact of CVE-2018-6437 is severe and far-reaching within enterprise network environments that utilize Brocade fabric switches. A successful exploitation could result in complete compromise of the network fabric, allowing attackers to view, modify, or delete sensitive network configuration data, access network traffic, and potentially disrupt network operations. The vulnerability affects the core administrative interface of the fabric switch, meaning that any local user with access to the CLI could exploit this weakness without requiring additional network access or specialized tools. Network administrators face the challenge of identifying and mitigating this vulnerability across multiple versions of the operating system, as the affected versions span several major releases and require specific patching strategies. The impact extends beyond simple privilege escalation to include potential data exfiltration, network disruption, and compromise of the integrity of the entire fabric infrastructure.
Mitigation strategies for CVE-2018-6437 primarily involve applying the vendor-provided security patches and updates that address the command injection vulnerability in the help command implementation. Organizations should prioritize patching all affected Brocade Fabric OS versions, particularly those running versions before 8.2.1, 8.1.2f, 8.0.2f, and 7.4.2d, as these are specifically identified as vulnerable. Additionally, implementing network segmentation and access controls can help limit the potential impact of exploitation by restricting local access to fabric switches. Security monitoring should be enhanced to detect unusual CLI activity patterns that might indicate exploitation attempts, including unexpected command execution or privilege escalation activities. The vulnerability aligns with CWE-78 and CWE-20 categories, representing command injection and input validation flaws respectively, and maps to ATT&CK technique T1059.003 for command and scripting interpreter, as attackers would leverage command injection to execute malicious payloads. Organizations should also consider implementing additional logging and auditing measures to track CLI interactions and detect potential exploitation attempts within their network fabric environments.