CVE-2021-20702 in Transaction Server CLUSTERPRO X
Summary
by MITRE • 11/03/2021
Buffer overflow vulnerability in the Transaction Server CLUSTERPRO X 1.0 for Windows and later, EXPRESSCLUSTER X 1.0 for Windows and later allows attacker to remote code execution via a network.
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Analysis
by VulDB Data Team • 11/06/2021
The CVE-2021-20702 vulnerability represents a critical buffer overflow flaw affecting Fujitsu's Transaction Server CLUSTERPRO X 1.0 and EXPRESSCLUSTER X 1.0 software implementations for Windows operating systems. This vulnerability resides within the network communication handling mechanisms of these clustering solutions, creating a pathway for remote attackers to execute arbitrary code on affected systems. The flaw specifically manifests when the software processes incoming network requests through its cluster management protocols, where insufficient input validation and bounds checking allows maliciously crafted data to overwrite adjacent memory regions. Such buffer overflow conditions typically occur when the application fails to properly validate the size of incoming data before copying it into fixed-size memory buffers, creating opportunities for attackers to manipulate program execution flow through carefully constructed payloads. The vulnerability's classification as a remote code execution threat underscores its severity since attackers can exploit this weakness from any network location without requiring local system access or authentication credentials.
The technical exploitation of this buffer overflow vulnerability follows standard patterns observed in similar clustering and enterprise software flaws, aligning with common weakness enumerations such as CWE-121, which describes heap-based buffer overflow conditions. Attackers can leverage this vulnerability by sending specially crafted network packets designed to exceed the allocated buffer size, causing memory corruption that can be manipulated to redirect program execution to attacker-controlled code. The network-based nature of this vulnerability means that systems exposed to the internet or internal networks without proper segmentation are at risk, particularly when the affected software operates on default or commonly used ports for cluster communication protocols. This type of vulnerability is particularly dangerous in enterprise environments where clustering solutions manage critical infrastructure components, as successful exploitation could provide attackers with elevated privileges and persistent access to entire cluster networks. The ATT&CK framework categorizes such vulnerabilities under the T1203 technique for legitimate credentials and T1059 for command and scripting interpreter, as exploitation typically involves executing malicious code that can establish further footholds within the compromised environment.
Organizations utilizing Fujitsu CLUSTERPRO X 1.0 or EXPRESSCLUSTER X 1.0 software must implement immediate mitigation strategies to protect their infrastructure from potential exploitation attempts. The primary recommendation involves applying vendor-provided security patches and updates as soon as they become available, since Fujitsu has released fixes specifically addressing this buffer overflow condition. Network segmentation and firewall configuration should be implemented to restrict access to cluster management ports and services, limiting the attack surface for potential exploitation. Additionally, monitoring network traffic for unusual patterns or malformed packets that might indicate exploitation attempts can provide early detection capabilities. System administrators should also consider implementing intrusion detection systems that can identify and alert on network traffic patterns consistent with buffer overflow exploitation attempts. The vulnerability's impact extends beyond immediate code execution capabilities, as successful exploitation could lead to complete system compromise and unauthorized access to sensitive data within cluster environments. Organizations should conduct thorough vulnerability assessments to identify all instances of affected software and implement comprehensive patch management procedures to ensure all systems remain protected against similar vulnerabilities in the future. Given the nature of clustering solutions and their role in enterprise infrastructure, regular security assessments and penetration testing should be conducted to validate the effectiveness of implemented mitigations and identify potential additional attack vectors that may exist within the broader network environment.