CVE-2021-32976 in NPort IAW5000A
Summary
by MITRE • 04/02/2022
Five buffer overflows in the built-in web server in Moxa NPort IAW5000A-I/O series firmware version 2.2 or earlier may allow a remote attacker to initiate a denial-of-service attack and execute arbitrary code.
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Analysis
by VulDB Data Team • 04/05/2022
The vulnerability identified as CVE-2021-32976 represents a critical security flaw affecting Moxa NPort IAW5000A-I/O series devices running firmware version 2.2 or earlier. This issue resides within the device's built-in web server implementation, creating multiple buffer overflow conditions that can be exploited by remote attackers. The affected devices are commonly used in industrial environments for serial communication management and network connectivity, making this vulnerability particularly concerning for operational technology infrastructure. These industrial devices often operate in critical systems where availability and security are paramount, and the presence of multiple buffer overflows significantly increases the attack surface and potential impact of exploitation.
The technical implementation of this vulnerability stems from inadequate input validation within the web server component of the Moxa firmware. Buffer overflows occur when the system attempts to write more data into a fixed-length buffer than it can accommodate, leading to memory corruption that can be leveraged by attackers. The presence of five distinct buffer overflow conditions indicates a systemic issue in the codebase rather than isolated incidents, suggesting poor coding practices and insufficient memory management controls. These vulnerabilities are classified under CWE-121 as stack-based buffer overflow conditions, which are particularly dangerous because they can be exploited to overwrite adjacent memory locations including return addresses and function pointers, enabling arbitrary code execution.
From an operational perspective, this vulnerability creates a significant risk of both denial-of-service attacks and remote code execution capabilities. A remote attacker could potentially exploit these buffer overflows to crash the device's web server, rendering the device inaccessible to authorized users and disrupting industrial communication processes. More critically, successful exploitation could allow attackers to execute arbitrary code on the affected devices, potentially leading to complete system compromise. The impact extends beyond simple service disruption as these industrial devices often serve as gateways for critical network communications, making them attractive targets for attackers seeking to establish persistent access points within industrial networks. The vulnerability affects devices that are typically deployed in remote locations with limited physical security, making exploitation more feasible and remediation more challenging.
Mitigation strategies for CVE-2021-32976 should prioritize immediate firmware updates from Moxa to address the identified buffer overflow conditions. Organizations should also implement network segmentation to limit access to these industrial devices, employing firewalls and access control lists to restrict web server access to trusted IP addresses only. Network monitoring should be enhanced to detect unusual traffic patterns or attempts to access the web server interface. The vulnerability aligns with ATT&CK technique T1210 which involves exploiting vulnerabilities in remote services to gain system access, and T1499 which covers network disruption attacks that could be initiated through denial-of-service exploits. Additionally, implementing secure configuration practices for industrial devices, including disabling unnecessary services and applying principle of least privilege access controls, will help reduce the attack surface. Regular vulnerability assessments and penetration testing should be conducted to identify similar issues in other industrial equipment and ensure comprehensive security coverage across the operational technology infrastructure.