How to remediate – OpenTSDB HTTP Detection

1. Introduction

OpenTSDB HTTP Detection indicates a time series database is running on a remote host. OpenTSDB stores and processes large volumes of timestamped data, often used for monitoring infrastructure and applications. A publicly accessible instance could allow information disclosure. This vulnerability has a likely impact of low confidentiality, medium integrity, and low availability.

2. Technical Explanation

The vulnerability occurs because OpenTSDB can be accessed via HTTP without authentication by default if not properly configured. An attacker can query the database to retrieve stored time series data. There is no known CVE associated with this specific detection, but it represents a misconfiguration risk. For example, an attacker could use curl to request data directly from the OpenTSDB instance.

• Root cause: Missing or weak authentication on the HTTP interface.
• Exploit mechanism: An attacker sends HTTP requests to the OpenTSDB server to retrieve time series data without providing credentials.
• Scope: All versions of OpenTSDB are potentially affected if not configured with appropriate security measures.

3. Detection and Assessment

Confirming a vulnerable system involves checking for an accessible HTTP interface and identifying the OpenTSDB version. A quick check can determine if the service is listening on standard ports, while thorough scanning identifies specific versions and configurations.

• Quick checks: Use netstat or ss to see if a process is listening on port 4242 (the default).
• Scanning: Nessus plugin ID 16358 can identify OpenTSDB instances. This is an example only, and results should be verified manually.
• Logs and evidence: Check web server logs for requests to the OpenTSDB port (e.g., 4242) without authentication.

netstat -tulnp | grep 4242

4. Solution / Remediation Steps

Fixing this issue requires configuring authentication on the OpenTSDB HTTP interface. The steps below outline how to secure access and prevent unauthorized data retrieval.

4.1 Preparation

• Ensure you have access to the OpenTSDB configuration files. A roll back plan involves restoring the original configuration file and restarting the service.
• A change window may be required for production systems; approval from a system owner is recommended.

4.2 Implementation

1. Step 1: Edit the OpenTSDB configuration file (typically opentsdb.conf) and enable authentication.
2. Step 2: Configure user accounts with appropriate permissions using the usersdef file.
3. Step 3: Restart the OpenTSDB service to apply the changes.

4.3 Config or Code Example

Before

# opentsdb.conf
# No authentication configured
auth.required = false

After

# opentsdb.conf
# Authentication enabled
auth.required = true
# usersdef file (example)
user1:password1:read

4.4 Security Practices Relevant to This Vulnerability

Several security practices directly address this vulnerability type. Least privilege limits the impact of a successful attack, while input validation can prevent malicious requests.

• Practice 1: Implement least privilege for OpenTSDB users, granting only necessary access rights.
• Practice 2: Regularly review and update user accounts and passwords.

4.5 Automation (Optional)

# Example Ansible task to enable authentication in opentsdb.conf
- name: Enable OpenTSDB Authentication
  lineinfile:
    path: /etc/opentsdb/opentsdb.conf
    regexp: '^auth.required = false$'
    line: 'auth.required = true'
  notify: Restart OpenTSDB

5. Verification / Validation

Confirming the fix involves verifying that authentication is now required to access the OpenTSDB interface. A post-fix check confirms the configuration change, and a re-test demonstrates the vulnerability is resolved.

• Post-fix check: Use curl to attempt accessing data without credentials; it should return an authentication error (e.g., HTTP 401).
• Re-test: Re-run the Nessus scan or manual checks from step 3 and confirm that the vulnerability is no longer reported.
• Smoke test: Verify that authorized users can still access and query data through the OpenTSDB interface.
• Monitoring: Monitor web server logs for failed authentication attempts to identify potential attacks.

curl http://opentsdb-server:4242/api/query?cmd=get&filter=hostname%3Dexample.com
# Expected output: HTTP 401 Unauthorized

6. Preventive Measures and Monitoring

Update security baselines to include OpenTSDB authentication requirements. Implement checks in CI or deployment pipelines to prevent insecure configurations.

• Baselines: Update a security baseline (e.g., CIS benchmark) to require HTTP authentication for OpenTSDB instances.
• Pipelines: Add SAST or configuration scanning to detect missing authentication settings during deployments.
• Asset and patch process: Review OpenTSDB configurations regularly as part of an asset management process, at least quarterly.

7. Risks, Side Effects, and Roll Back

Enabling authentication may require changes to existing monitoring tools or applications that access OpenTSDB. Incorrect configuration can lock out legitimate users.

• Risk or side effect 1: Existing monitoring scripts may need updating with credentials.
• Risk or side effect 2: Misconfigured user accounts could prevent access for authorized personnel.
• Roll back: Restore the original opentsdb.conf file and restart the OpenTSDB service.

8. References and Resources

• Vendor advisory or bulletin: http://opentsdb.net/