1. Introduction
The Contec CONPROSYS HMI System (CHS) is running a web application on the remote host, presenting a potential attack surface. This means an attacker could access and control the system remotely. This vulnerability affects industrial control systems that use the CHS software, potentially impacting confidentiality, integrity, and availability of processes they manage.
2. Technical Explanation
The Contec CONPROSYS HMI System (CHS) includes a web application which is accessible without authentication. An attacker can access this web application remotely to gain control of the system. There are no known CVEs associated with this specific issue, but it represents a significant risk due to the lack of security measures on the exposed web interface. A realistic example would be an attacker accessing sensitive configuration data or modifying process parameters through the web application.
- Root cause: The CHS system runs a web application accessible without authentication.
- Exploit mechanism: An attacker connects to the web application on the remote host and gains access to its functionality.
- Scope: Contec CONPROSYS HMI System (CHS) software is affected.
3. Detection and Assessment
To confirm whether a system is vulnerable, first check for the presence of the web application. A thorough method involves attempting to access the application directly from an external network.
- Quick checks: Attempt to browse to the IP address of the CHS device in a web browser. If a login page or other web interface appears without requiring authentication, the system is likely vulnerable.
- Scanning: Nessus vulnerability scan ID 4999de20 can be used as an example for detection.
- Logs and evidence: Review web server logs on the CHS device for any unauthorized access attempts or connections from unexpected sources.
# Example command placeholder:
# No direct command to confirm exposure, use browser test.
4. Solution / Remediation Steps
To fix this issue, restrict access to the web application running on the Contec CONPROSYS HMI System (CHS). This can be achieved through firewall rules or by disabling the web server if it is not required.
4.1 Preparation
- Ensure you have access to the firewall or system configuration settings. A roll back plan involves restoring the snapshot if issues occur.
- Change windows may be required depending on business impact, and approval from IT management is recommended.
4.2 Implementation
- Step 1: Configure a firewall rule to block external access to port 80 or 443 (or the relevant web application port) on the CHS device.
- Step 2: If the web application is not required, disable it within the CONPROSYS HMI System configuration settings.
4.3 Config or Code Example
Before
# No specific config example available, as this is a firewall/system setting. Assume open port 80 or 443.
After
# Firewall rule blocking external access to port 80 and 443 on CHS device IP address. Example (iptables):
# iptables -A INPUT -p tcp --dport 80 -j DROP
# iptables -A INPUT -p tcp --dport 443 -j DROP
4.4 Security Practices Relevant to This Vulnerability
Several security practices can help prevent this issue. Least privilege reduces the impact if exploited, and input validation blocks unsafe data. Secure defaults ensure systems are configured safely from the start. A regular patch cadence keeps systems up-to-date with the latest security fixes.
- Practice 1: Implement least privilege to limit access to sensitive resources.
- Practice 2: Use input validation to prevent malicious data from being processed by web applications.
4.5 Automation (Optional)
# Example Ansible playbook snippet to block ports:
# - name: Block access to web application ports
# firewalld:
# port: 80/tcp,443/tcp
# permanent: true
# state: disabled
# immediate: yes
5. Verification / Validation
- Post-fix check: Attempt to browse to the CHS device IP address in a web browser. Access should be denied, resulting in a connection error or timeout.
- Re-test: Re-run the quick check from Section 3; access should no longer be possible.
- Smoke test: Verify that other essential system functions (e.g., data logging, process control) are still working as expected.
# Post-fix command and expected output:
# Attempt to browse to CHS IP address in a web browser - Connection timed out or access denied.
6. Preventive Measures and Monitoring
Update security baselines to include restrictions on unnecessary web application exposure. Add checks in CI/CD pipelines to identify open ports during deployment. Implement a regular patch or configuration review cycle that fits the risk profile of your industrial control systems.
- Baselines: Update a security baseline or policy to restrict external access to port 80 and 443 on CHS devices.
- Pipelines: Add checks in CI/CD pipelines to scan for open ports during deployment.
- Asset and patch process: Implement a quarterly review of system configurations to ensure compliance with security policies.
7. Risks, Side Effects, and Roll Back
Blocking access to the web application may disrupt remote management capabilities if they rely on this interface. Disabling the service could impact other functionality. To roll back, remove the firewall rule or re-enable the web application within the CONPROSYS HMI System configuration settings.
- Risk or side effect 1: Blocking access to the web application may disrupt remote management if it is used for this purpose.
- Risk or side effect 2: Disabling the service could impact other functionality that relies on it.
- Roll back: Step 1: Remove the firewall rule blocking external access. Step 2: Re-enable the web application within the CONPROSYS HMI System configuration settings.
8. References and Resources
- Vendor advisory or bulletin: http://www.nessus.org/u?4a99de20