How to remediate – Apache CouchDB Unauthenticated Administrative Access

1. Introduction

Apache CouchDB Unauthenticated Administrative Access allows administrative actions on a database server without requiring login credentials. This means an attacker could gain full control of the database, potentially stealing sensitive data or disrupting service. Systems running Apache CouchDB with default configurations are usually affected. A successful exploit could lead to complete loss of confidentiality, integrity and availability of the database.

2. Technical Explanation

The vulnerability occurs because CouchDB does not enforce authentication for administrative functions by default. This allows an attacker to remotely access the server’s configuration and perform actions like creating databases, modifying settings, or deleting data without any credentials. The root cause is a missing access check on administrative endpoints.

• Root cause: Lack of required authentication for administrative API endpoints.
• Exploit mechanism: An attacker can send HTTP requests directly to the CouchDB server’s administrative interface, bypassing login prompts. For example, an attacker could use curl to create a new database without providing any username or password.
• Scope: Apache CouchDB versions prior to 2.3.1 are affected.

3. Detection and Assessment

To confirm vulnerability, check if administrative access is possible without authentication. A quick check involves attempting to create a database via the API without credentials. For thorough assessment, use a dedicated scanner or review CouchDB configuration files.

• Quick checks: Use curl to attempt creating a new database: curl -X PUT http://:5984/testdb. If successful (HTTP 201 Created), the system is vulnerable.
• Scanning: Nessus plugin ID 16379 can detect this vulnerability. Other scanners may have similar checks.
• Logs and evidence: Check CouchDB logs for administrative actions originating from unknown or unexpected sources. Log files are typically located in the data directory.

curl -X PUT http://<couchdb_server>:5984/testdb

4. Solution / Remediation Steps

Secure the CouchDB installation by configuring an administrative account with a strong password. This will require authentication for all administrative actions, preventing unauthorized access.

4.1 Preparation

• Ensure you have a valid administrator account or create one. A roll back plan involves restoring the backup if issues occur.
• A change window may be required depending on service criticality and downtime tolerance.

4.2 Implementation

1. Step 1: Edit the CouchDB configuration file (local.ini) located in the configuration directory.
2. Step 2: Add or modify the [admins] section to define an administrative user and password. For example, add a line like admin = your_password.
3. Step 3: Restart the CouchDB service for the changes to take effect.

4.3 Config or Code Example

Before

# local.ini file - no admins section defined
;[admins]

After

[admins]
admin = your_password

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this type of vulnerability. Least privilege reduces the impact if an attacker gains access. Secure defaults ensure a strong initial configuration. Input validation prevents malicious data from being processed. A regular patch cadence ensures timely updates and fixes.

• Practice 1: Implement least privilege to limit the scope of administrative accounts.
• Practice 2: Use secure defaults for all configurations, including authentication requirements.

4.5 Automation (Optional)

Automation is not recommended due to the risk of misconfiguration. However, configuration management tools can be used to enforce a standard CouchDB configuration with administrative access enabled.

# Example Ansible task - use with caution!
- name: Configure CouchDB admins
  copy:
    src: local.ini
    dest: /opt/couchdb/etc/local.ini
    owner: couchdb
    group: couchdb
    mode: 0640

5. Verification / Validation

Confirm the fix by attempting to access administrative functions without credentials. Verify that authentication is now required and that unauthorized access is blocked. Perform a service smoke test to ensure functionality remains intact.

• Post-fix check: Use curl to attempt creating a new database again: curl -X PUT http://:5984/testdb. This should now return an HTTP 401 Unauthorized error.
• Re-test: Re-run the initial detection method (attempting administrative actions without credentials) to confirm it is blocked.
• Smoke test: Verify that authorized users can still access and modify data through the CouchDB web interface or API with valid credentials.

curl -X PUT http://<couchdb_server>:5984/testdb

6. Preventive Measures and Monitoring

Update security baselines to include mandatory authentication for CouchDB administrative access. Implement checks in CI or deployment pipelines to ensure configurations adhere to the baseline. Establish a regular patch review cycle to apply security updates promptly. For example, use CIS benchmarks to guide configuration.

• Baselines: Update your security baseline to require an administrator account and password for CouchDB.
• Pipelines: Add checks in CI/CD pipelines to validate the [admins] section in local.ini during deployment.

7. Risks, Side Effects, and Roll Back

Enabling authentication may require changes to existing applications that access CouchDB. Incorrect configuration can lock out administrators. To roll back, restore the original backup of the CouchDB data directory or revert the changes made to local.ini.

• Risk or side effect 1: Existing applications may need updates to provide credentials.
• Risk or side effect 2: Incorrect configuration can prevent access for all users, including administrators.
• Roll back: 1) Stop the CouchDB service. 2) Restore the backed-up data directory. 3) Restart the CouchDB service.

8. References and Resources

• Vendor advisory or bulletin: http://books.couchdb.org/relax/reference/security