CVE-2020-6989 in PT-7528
Summary
by MITRE
In Moxa PT-7528 series firmware, Version 4.0 or lower, and PT-7828 series firmware, Version 3.9 or lower, a buffer overflow in the web server allows remote attackers to cause a denial-of-service condition or execute arbitrary code.
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Analysis
by VulDB Data Team • 05/11/2024
The vulnerability identified as CVE-2020-6989 affects Moxa PT-7528 and PT-7828 series industrial network devices, representing a critical security flaw in their firmware implementations. These devices are part of Moxa's industrial automation product line designed for remote monitoring and control applications in critical infrastructure environments. The affected firmware versions contain a buffer overflow condition within the web server component that serves as the primary interface for device management and configuration. This vulnerability exists in firmware versions 4.0 and earlier for PT-7528 series and version 3.9 and earlier for PT-7828 series, indicating a widespread issue affecting multiple generations of these industrial communication devices. The buffer overflow condition specifically manifests in the web server's handling of incoming network requests, creating a potential attack surface that can be exploited by remote threat actors without requiring authentication or physical access to the devices.
The technical flaw stems from improper input validation within the web server implementation where user-supplied data is copied into fixed-size buffers without adequate bounds checking. This classic buffer overflow vulnerability occurs when the web server receives malformed HTTP requests or parameters that exceed the allocated buffer space, causing memory corruption that can be exploited to execute arbitrary code or induce system instability. The vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and represents a direct threat to the integrity of industrial control systems. Attackers can leverage this weakness by crafting specially designed network requests that trigger the buffer overflow during request processing, potentially leading to complete system compromise or denial-of-service conditions. The remote nature of the attack vector means that threat actors can exploit this vulnerability from outside the local network perimeter, making it particularly dangerous for industrial environments where these devices may be exposed to internet-facing networks.
The operational impact of CVE-2020-6989 extends beyond simple denial-of-service conditions to encompass full system compromise capabilities that could severely disrupt industrial operations. In industrial control environments, these devices typically serve as critical communication bridges between field devices and centralized monitoring systems, making their compromise potentially catastrophic for operational continuity. The vulnerability enables attackers to execute arbitrary code with the privileges of the web server process, which may have elevated system permissions depending on the device configuration. This could allow threat actors to gain persistent access to industrial networks, potentially leading to data exfiltration, system manipulation, or disruption of critical processes. The impact is particularly severe in environments where these devices are used for SCADA systems, process control, or other critical infrastructure applications where system availability and integrity are paramount. Organizations operating these devices face significant risk of operational disruption, potential safety hazards, and compliance violations when such vulnerabilities remain unaddressed.
Mitigation strategies for CVE-2020-6989 should prioritize immediate firmware updates from Moxa to address the buffer overflow vulnerability in affected device models. Organizations must conduct comprehensive inventory assessments to identify all affected PT-7528 and PT-7828 series devices within their networks and implement network segmentation to limit exposure of these devices to untrusted networks. Security controls should include disabling unnecessary web server functionality when not required for operations, implementing network access controls to restrict web server access to authorized personnel only, and establishing monitoring procedures to detect anomalous network traffic patterns that may indicate exploitation attempts. The vulnerability's alignment with ATT&CK technique T1210, which covers exploitation of remote services, underscores the importance of maintaining current threat intelligence and implementing network-based intrusion detection systems. Additionally, organizations should consider implementing compensating controls such as web application firewalls, network monitoring solutions, and regular security assessments to detect and prevent exploitation attempts. Given the industrial nature of these devices, organizations should also evaluate their incident response capabilities to ensure rapid detection and remediation of potential compromise scenarios, as these devices often operate in environments where traditional IT security controls may be insufficient or inappropriate.