CVE-2021-27794 in Fabric OS
Summary
by MITRE • 08/12/2021
A vulnerability in the authentication mechanism of Brocade Fabric OS versions before Brocade Fabric OS v.9.0.1a, v8.2.3a and v7.4.2h could allow a user to Login with empty password, and invalid password through telnet, ssh and REST.
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Analysis
by VulDB Data Team • 08/18/2021
This vulnerability represents a critical authentication flaw in Brocade Fabric OS networking equipment that undermines fundamental security controls. The issue affects multiple major versions including v9.0.1a, v8.2.3a, and v7.4.2h, indicating a persistent weakness in the authentication implementation that spans across several software releases. The vulnerability specifically targets the telnet, ssh, and REST authentication mechanisms, which are essential for remote management and administration of storage area networks. The flaw allows unauthorized access through empty password attempts and invalid password submissions, effectively bypassing the authentication process entirely. This represents a classic example of improper authentication handling that violates security best practices and exposes network infrastructure to potential compromise.
The technical implementation of this vulnerability stems from inadequate input validation and authentication logic within the Brocade Fabric OS authentication subsystem. When users attempt to establish connections through telnet, ssh, or REST protocols, the system fails to properly validate credential inputs, allowing empty or malformed credentials to be accepted as valid authentication. This weakness directly maps to CWE-287, which addresses improper authentication vulnerabilities in software systems. The flaw exists at the protocol level where authentication requests are processed without sufficient validation checks, creating an authentication bypass condition that can be exploited by malicious actors. The vulnerability demonstrates poor security design where the system should have implemented robust credential validation but instead accepted any input without proper verification mechanisms.
The operational impact of this vulnerability is severe and far-reaching for organizations relying on Brocade storage fabric infrastructure. Network administrators and attackers alike can gain unauthorized access to critical storage network components without requiring legitimate credentials, potentially leading to data breaches, network disruption, and unauthorized modifications to storage configurations. The vulnerability affects remote management capabilities across multiple protocols, amplifying the attack surface and making exploitation more feasible. Organizations with exposed storage fabrics become vulnerable to lateral movement within their network infrastructure, as storage networks often serve as critical pathways for data access and transfer. This vulnerability can be exploited as part of broader attack campaigns targeting enterprise storage infrastructure, potentially enabling data exfiltration or storage network disruption that impacts business continuity.
Organizations should immediately implement mitigations including updating to the patched versions of Brocade Fabric OS as specified in the vendor advisories, disabling unnecessary remote access protocols where possible, and implementing additional network segmentation controls. The remediation process requires careful planning due to the critical nature of storage infrastructure, with potential impacts on network operations during patching activities. Security teams should conduct comprehensive vulnerability assessments to identify all affected devices and establish monitoring for potential exploitation attempts. Additional defensive measures include implementing strong network access controls, enabling multi-factor authentication where supported, and conducting regular security audits of remote management interfaces. This vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and legitimate credentials as a means of gaining access to systems, and represents a significant risk to enterprise security posture when storage networks are not properly secured.