How to remediate – Visual Mining NetCharts Server Arbitrary File Upload

1. Introduction

The Visual Mining NetCharts Server Arbitrary File Upload vulnerability allows an attacker to upload files containing malicious code to a vulnerable web server. This could allow them to execute commands on the server, potentially compromising its confidentiality, integrity and availability. Systems running the Visual Mining NetCharts Server software are typically affected. A successful exploit can lead to complete system takeover.

2. Technical Explanation

This vulnerability exists because of a hidden account within the Visual Mining NetCharts Server web interface. This allows an unauthenticated attacker to upload files without proper restrictions, leading to arbitrary code execution on the host server. The CVE for this issue is CVE-2014-8516. An example attack involves uploading a PHP shell script through the vulnerable interface and then accessing it via a web browser to execute commands.

• Root cause: Lack of input validation on uploaded files combined with an accessible hidden account.
• Exploit mechanism: An attacker sends a malicious file upload request to the server’s JSP script, bypassing authentication due to the hidden account. The uploaded file is then executed by the web server.
• Scope: Visual Mining NetCharts Server software is affected. Specific versions are not detailed in the provided information.

3. Detection and Assessment

• Quick checks: Check for the existence of the NetCharts Server installation path, typically /opt/netcharts or C:Program FilesVisual MiningNetCharts Server.
• Scanning: Nessus plugin ID 70895 may detect this vulnerability as an example only.
• Logs and evidence: Examine web server access logs for requests to JSP scripts within the NetCharts installation directory, looking for unusual file uploads or activity from unexpected sources.

ls /opt/netcharts

4. Solution / Remediation Steps

The following steps provide a precise method to fix this issue. These steps are designed to be testable and safe to roll back.

4.1 Preparation

• Ensure you have access to restore the backup in case of issues. A rollback plan involves restoring from the pre-change backup.
• Changes should be scheduled during a maintenance window with appropriate approval from IT management.

4.2 Implementation

1. Step 1: Restrict all external access to the vulnerable server using firewall rules. Block inbound traffic on ports used by the web server (typically 80 and 443).
2. Step 2: If possible, disable or remove the hidden account responsible for the file upload vulnerability. Consult Visual Mining documentation for details.
3. Step 3: Apply any available security patches released by Visual Mining for NetCharts Server.

4.3 Config or Code Example

Before

# No specific configuration example available in provided context. Assume unrestricted access.

After

# Example firewall rule (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 type of issue. Least privilege reduces the impact if an attacker gains access. Input validation blocks unsafe data from being processed. Safe defaults minimise initial exposure.

• Practice 1: Implement least privilege principles, limiting user and application permissions to only what is necessary.
• Practice 2: Enforce strict input validation on all file uploads to prevent malicious code from being uploaded.

4.5 Automation (Optional)

# Example Ansible playbook snippet to block ports:
---
- hosts: all
  tasks:
    - name: Block inbound traffic on ports 80 and 443
      firewalld:
        port: "{{ item }}"
        permanent: true
        state: disabled
      loop: [80, 443]
      become: true

5. Verification / Validation

Confirm the fix worked by verifying restricted access and re-testing for the vulnerability. A simple service smoke test can ensure core functionality remains operational.

• Post-fix check: Attempt to access the NetCharts Server web interface from an external network; connection should be refused.
• Re-test: Repeat the file upload attempt described in section 2; it should now fail due to restricted access or input validation.
• Smoke test: Verify that legitimate users can still access other services hosted on the same server, if applicable.
• Monitoring: Monitor web server logs for any attempts to access the vulnerable JSP scripts and alert on suspicious activity.

telnet  80 # Should fail to connect

6. Preventive Measures and Monitoring

Update security baselines and implement checks in CI/CD pipelines to prevent similar issues. A sensible patch or config review cycle fits the risk.

• Baselines: Update your security baseline to include a requirement for restricting access to web server administration interfaces.
• Asset and patch process: Implement a regular patch management cycle with timely review of vendor security advisories.

7. Risks, Side Effects, and Roll Back

Blocking all access may disrupt legitimate users if not carefully planned. Restoring from backup is the primary rollback method.

• Risk or side effect 1: Blocking ports could impact other services running on the same server; ensure proper exception rules are in place.
• Risk or side effect 2: Disabling/removing the hidden account may require specific knowledge of the NetCharts Server configuration.
• Roll back:
  1. Step 1: Re-enable blocked ports using firewall rules.
  2. Step 2: Restore the server from the pre-change backup if necessary.

8. References and Resources

• Vendor advisory or bulletin: https://www.zerodayinitiative.com/advisories/ZDI-14-372/
• NVD or CVE entry: CVE-2014-8516
• Product or platform documentation relevant to the fix: No specific link available in provided context.