CVE-2016-4523
Trihedral VTScada (formerly VTS) Denial-of-Service Vulnerability
Description
CVE-2016-4523 is a denial-of-service vulnerability in Trihedral VTScada (formerly VTS), an industrial SCADA platform used for monitoring and controlling critical infrastructure systems. The flaw resides in the WAP interface, where a specially crafted request can crash the application, disrupting supervisory control operations. CISA has added CVE-2016-4523 to the Known Exploited Vulnerabilities catalog, confirming real-world exploitation against industrial control systems. With an EPSS score of 0.67% (98.5th percentile), this vulnerability ranks among the most likely to be exploited across all tracked CVEs, demanding urgent attention from organizations running VTScada in operational technology environments.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| trihedral | vtscada | >= 8.0.05, < 11.2.02 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- http://www.securityfocus.com/bid/91077(Broken Link, Third Party Advisory, VDB Entry)
- http://www.zerodayinitiative.com/advisories/ZDI-16-405(Third Party Advisory, VDB Entry)
- https://ics-cert.us-cert.gov/advisories/ICSA-16-159-01(Third Party Advisory, US Government Resource)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2016-4523(US Government Resource)
Weakness Type
CWE-400: Uncontrolled Resource Consumption
CWE-400 describes a weakness where software does not properly control the allocation and maintenance of a limited resource, allowing an attacker to consume resources excessively and cause a denial of service. In CVE-2016-4523, the VTScada WAP interface fails to properly validate or limit incoming requests, enabling an attacker to send crafted input that exhausts system resources and crashes the SCADA application.
Learn more: CWE-400 — Uncontrolled Resource Consumption
Impact Analysis
CVE-2016-4523 enables a remote attacker to crash the VTScada application through its WAP interface without requiring authentication, directly disrupting industrial monitoring and control operations. While the vulnerability primarily affects availability rather than confidentiality or integrity, the impact on operational technology environments is severe — loss of SCADA visibility can delay detection of physical process anomalies and potentially create unsafe conditions. Organizations relying on VTScada for critical infrastructure monitoring face operational blindness during exploitation, which adversaries can leverage as a diversion while conducting deeper intrusions into industrial control networks. The EPSS score of 0.67% (98.5th percentile) and KEV catalog listing confirm that this is not a theoretical risk but an actively targeted vulnerability.
Exploit Maturity
CVE-2016-4523 is listed in the CISA Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild against industrial control system deployments. The EPSS score of 0.67% (98.5th percentile) places this vulnerability well above the exploitation threshold for most organizations' risk models. Given the age of this vulnerability (disclosed in 2016) and its continued relevance in KEV, unpatched VTScada installations remain attractive targets for adversaries seeking to disrupt critical infrastructure operations.
Remediation
- Apply vendor patches immediately as required by CISA KEV: update Trihedral VTScada to the latest patched version that addresses the WAP interface denial-of-service vulnerability.
- Restrict network access to the VTScada WAP interface by implementing firewall rules that limit connections to authorized management stations only.
- Place VTScada servers in a segmented OT network zone, isolated from the corporate IT network and the internet, following ICS-CERT defense-in-depth recommendations.
- Monitor VTScada application logs and network traffic for anomalous WAP requests or unexpected service restarts that may indicate exploitation attempts.
- Establish a VTScada service recovery plan that includes automated restarts and alerting to minimize downtime during denial-of-service events.
Technical Details
CVE-2016-4523 is a denial-of-service vulnerability in the WAP (Wireless Application Protocol) interface of Trihedral VTScada, triggered by specially crafted requests that the application fails to properly validate or handle. When the malformed input reaches the WAP processing logic, it causes an uncontrolled resource consumption condition or unhandled exception that terminates the VTScada process. The vulnerability is remotely exploitable without authentication, requiring only network access to the WAP interface port. Given VTScada's role as a SCADA platform in industrial environments, the crash of this application can halt real-time monitoring and control of connected physical processes.
Frequently Asked Questions
Is CVE-2016-4523 being actively exploited?
Yes. CVE-2016-4523 is listed in the CISA Known Exploited Vulnerabilities catalog, confirming active exploitation against VTScada deployments. The EPSS score of 0.67% (98.5th percentile) further indicates a high probability of exploitation in the wild.
What products are affected by CVE-2016-4523?
CVE-2016-4523 affects Trihedral VTScada (formerly known as VTS), specifically its WAP interface component. Organizations using VTScada for SCADA monitoring and control should verify their version and apply available patches.
How do I fix CVE-2016-4523?
Update VTScada to the latest patched version from Trihedral. As an interim measure, restrict network access to the WAP interface and isolate VTScada servers within a segmented OT network to reduce exposure.
How severe is CVE-2016-4523?
CVE-2016-4523 is a denial-of-service vulnerability that can crash the VTScada SCADA platform, disrupting critical infrastructure monitoring. While it does not directly enable code execution, the operational impact on industrial environments is significant, and its KEV listing confirms it as a priority for remediation.
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