CVE-2021-20705 in WebManager CLUSTERPRO X
Summary
by MITRE • 11/03/2021
Improper input validation vulnerability in the WebManager CLUSTERPRO X 1.0 for Windows and later, EXPRESSCLUSTER X 1.0 for Windows and later allows attacker to remote file upload via network.
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Analysis
by VulDB Data Team • 11/06/2021
The vulnerability identified as CVE-2021-20705 represents a critical security flaw in the WebManager component of Fujitsu's ClusterPRO X and EXPRESSCLUSTER X software versions for Windows. This issue stems from inadequate input validation mechanisms within the web interface that governs cluster management operations. The vulnerability specifically affects systems running versions 1.0 and later of these clustering solutions, which are commonly deployed in enterprise environments for high availability and disaster recovery configurations. The flaw exists in the remote file upload functionality that is accessible through the web management interface, creating a pathway for malicious actors to execute unauthorized file operations on affected systems.
The technical exploitation of this vulnerability occurs through the manipulation of input parameters within the web-based management interface. Attackers can craft malicious requests that bypass proper validation checks, allowing them to upload arbitrary files to the target system. This improper input validation creates a direct pathway for remote code execution, as the uploaded files can contain malicious payloads that execute with the privileges of the web application or system services. The vulnerability falls under the category of CWE-20, which specifically addresses improper input validation, and represents a significant weakness in the application's security architecture. The flaw is particularly dangerous because it enables attackers to upload files without proper authentication or authorization, effectively granting them persistent access to the compromised system.
The operational impact of this vulnerability extends beyond simple unauthorized file uploads, as it provides attackers with a potential foothold for further system compromise. Once an attacker successfully uploads malicious files, they can leverage this access to establish persistent backdoors, escalate privileges, or deploy additional malicious tools within the network. The affected systems typically operate in critical infrastructure environments where cluster management services are essential for maintaining business continuity, making this vulnerability particularly attractive to threat actors. The remote nature of the exploit means that attackers can target these systems from outside the network perimeter, potentially leading to widespread compromise of cluster environments and disruption of critical services.
Organizations affected by this vulnerability should implement immediate mitigations including network segmentation to restrict access to the WebManager interface, deployment of web application firewalls to monitor and filter suspicious requests, and implementation of strict input validation controls. The recommended approach involves disabling unnecessary file upload functionality where possible, implementing robust authentication mechanisms, and applying the latest security patches provided by Fujitsu. From a threat hunting perspective, security teams should monitor for unusual file upload patterns and anomalous network traffic originating from the affected systems. The vulnerability aligns with ATT&CK technique T1190, which covers exploitation of remote services, and represents a clear example of how insufficient input validation can create persistent security risks in enterprise applications. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other web-based management interfaces within the organization's infrastructure.