CVE-2016-4821 in ETX-R
Summary
by MITRE
I-O DATA DEVICE ETX-R devices allow remote attackers to cause a denial of service (web-server crash) via unspecified vectors.
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Analysis
by VulDB Data Team • 01/30/2019
The I-O DATA DEVICE ETX-R series represents a line of embedded network appliances that have been identified with a critical vulnerability classified as CVE-2016-4821. These devices function as web-based network management systems that provide remote access capabilities for network administrators to monitor and control various network components. The vulnerability manifests as a remote denial of service condition that can be exploited by attackers located outside the network perimeter, potentially compromising the availability of critical network infrastructure. The affected devices operate using embedded web servers that process HTTP requests from remote clients, making them susceptible to various forms of malformed input or exploitation techniques that can cause the web server process to crash and terminate unexpectedly.
The technical nature of this vulnerability stems from insufficient input validation and error handling mechanisms within the web server component of the ETX-R devices. Attackers can leverage unspecified vectors to send crafted requests or data to the device's web interface, which triggers an unhandled exception or memory corruption within the server process. This flaw likely resides in the web server's request parsing logic or in how it handles specific HTTP headers, parameters, or content types that are not properly sanitized or validated before processing. The vulnerability classification as a remote denial of service indicates that no authentication is required to exploit the flaw, making it particularly dangerous as any remote attacker can potentially disrupt service without prior access credentials. The underlying issue demonstrates poor defensive programming practices that fail to implement proper exception handling and input validation mechanisms.
The operational impact of this vulnerability extends beyond simple service disruption as it can compromise the overall network infrastructure reliability and availability. When the web server crashes, administrators lose remote access to configure and monitor the device, potentially leaving network components unmanaged during critical maintenance windows or emergency situations. Network operators may experience extended downtime while technicians diagnose and restore service, particularly in environments where these devices serve as critical network management points. The vulnerability can be exploited repeatedly, allowing attackers to maintain persistent disruption of service, which may be particularly concerning in mission-critical environments such as data centers, telecommunications networks, or industrial control systems where availability is paramount. The flaw can also serve as an initial foothold for more sophisticated attacks, as the device may be used as a pivot point for further reconnaissance or exploitation of adjacent network segments.
Mitigation strategies for CVE-2016-4821 should include immediate firmware updates from I-O DATA DEVICE to address the underlying web server implementation issues. Network administrators should implement network segmentation and access controls to limit exposure of these devices to untrusted networks, particularly by placing them behind firewalls or network access control lists that restrict web server access. Additional protective measures include implementing intrusion detection systems that can monitor for unusual web server traffic patterns or known attack signatures associated with this vulnerability. The remediation process should also involve comprehensive network monitoring to detect any exploitation attempts or service disruptions that may occur during the patching process. Organizations should conduct vulnerability assessments to identify all instances of ETX-R devices within their network infrastructure and prioritize their remediation based on risk exposure and business criticality. The vulnerability aligns with CWE-20, which describes improper input validation, and represents a common pattern of security flaws that can be addressed through proper defensive coding practices and regular security updates.
This vulnerability demonstrates the importance of secure software development lifecycle practices, particularly in embedded systems where resource constraints may lead to inadequate security controls. The flaw exemplifies techniques described in the ATT&CK framework under the T1499 category for network denial of service attacks, where adversaries leverage system weaknesses to disrupt availability. Organizations should establish robust patch management procedures that include regular firmware updates for embedded network devices, as these systems often receive less frequent security attention compared to traditional enterprise systems. The incident highlights the need for continuous security assessment of network infrastructure components, particularly those that provide web-based management interfaces and are accessible from untrusted networks. Security teams should also consider implementing network access controls that limit the exposure of management interfaces to only necessary administrative networks, thereby reducing the attack surface for vulnerabilities like CVE-2016-4821.