CVE-2021-27792 in Fabric OS
Summary
by MITRE • 08/12/2021
The command “ipfilter” in Brocade Fabric OS before Brocade Fabric OS v.9.0.1a, v8.2.3, and v8.2.0_CBN4, and v7.4.2h uses unsafe string function to process user input. Authenticated attackers can abuse this vulnerability to exploit stack-based buffer overflows, allowing execution of arbitrary code as the root user account.
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Analysis
by VulDB Data Team • 08/18/2021
The vulnerability identified as CVE-2021-27792 represents a critical stack-based buffer overflow in the ipfilter command of Brocade Fabric OS versions prior to specific patches. This flaw exists within the fabric operating system that manages storage area networks and is particularly concerning due to its potential for privilege escalation. The vulnerability stems from the improper handling of user-supplied input through unsafe string functions, creating an exploitable condition that can be leveraged by authenticated attackers to execute arbitrary code with root privileges. The affected versions include Brocade Fabric OS v.9.0.1a, v8.2.3, v8.2.0_CBN4, and v7.4.2h, indicating a widespread issue across multiple release lines of the storage fabric operating system.
The technical implementation of this vulnerability involves the use of unsafe string handling functions that do not properly validate input length before copying data to fixed-size buffers on the stack. When an authenticated user submits malicious input to the ipfilter command, the vulnerable code fails to check whether the input exceeds the allocated buffer size, resulting in a stack-based buffer overflow condition. This overflow can overwrite adjacent stack memory locations including return addresses and control data, enabling attackers to manipulate program execution flow. The exploitation requires authentication since the vulnerability is accessible only to authenticated users within the fabric operating system, but the privilege escalation aspect means that any authenticated attacker can gain root access to the system.
From an operational impact perspective, this vulnerability presents a severe risk to enterprise storage infrastructure since it allows for complete system compromise with root privileges. Storage area networks managed by Brocade Fabric OS are critical components of enterprise data centers, and compromise of these systems can lead to unauthorized access to sensitive data, disruption of business operations, and potential data exfiltration. The vulnerability's exploitation can result in persistent access to the storage fabric, enabling attackers to manipulate storage configurations, redirect traffic, or establish backdoors within the network infrastructure. The fact that this affects multiple major release versions indicates that organizations with legacy deployments may be particularly vulnerable, as they might not have upgraded to patched versions yet.
The vulnerability maps to CWE-121 Stack-based Buffer Overflow within the Common Weakness Enumeration catalog, which specifically addresses buffer overflows occurring in stack memory regions. This weakness is categorized under the broader class of buffer overflow vulnerabilities that can lead to arbitrary code execution. The attack pattern aligns with techniques described in the MITRE ATT&CK framework under the T1059.007 sub-technique for Command and Scripting Interpreter, where attackers leverage legitimate system utilities to execute malicious code. Organizations should implement immediate mitigations including applying the vendor-provided patches for Brocade Fabric OS, restricting access to the ipfilter command through network segmentation, and monitoring for unusual authentication patterns or command execution within the fabric management interfaces.
Security teams should prioritize this vulnerability for remediation due to its combination of authenticated access requirement with root privilege escalation capabilities. The patching process should include thorough testing in non-production environments to ensure compatibility with existing storage fabric configurations. Additionally, organizations should consider implementing network access controls to limit who can access the fabric management interfaces and monitor for anomalous command usage patterns that might indicate exploitation attempts. The vulnerability underscores the importance of secure coding practices in network infrastructure software and highlights the critical need for regular security updates in enterprise storage systems.