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Mitigation Strategies Analysis for apache/couchdb

Mitigation Strategy: Restrict Access to Administrative Endpoints

Description:

  1. Identify Sensitive Endpoints: Identify all administrative endpoints within CouchDB, including _all_dbs, _all_docs, _config, _replicate, and the web interfaces (Futon/Fauxton).
  2. Configure Security Objects: Within CouchDB, use security objects (defined per-database in the _security document) to restrict access to these endpoints. Create roles (e.g., "admin", "replicator") and assign appropriate permissions using the admins and members sections (with names and roles arrays). For example, to restrict _all_docs, you would configure the security object for the relevant database.
  3. User Management: Create user accounts within the _users database. Assign users to the appropriate roles defined in the security objects. Use strong, unique passwords. The _users database itself should have a very restrictive security object.
  4. Disable Web Interfaces (Production): In production environments, completely disable Futon/Fauxton by setting [httpd] enable_cors = false and [cors] origins = "" in the CouchDB configuration (local.ini or similar). Alternatively, set the [httpd] bind_address to 127.0.0.1 to restrict access to localhost only. This is a configuration change within CouchDB, even though it affects external access.
  5. Regularly review user accounts and permissions. Remove or disable accounts in the _users database that are no longer needed. Review the security objects of all databases.

Threats Mitigated:

  • Unintentional Data Exposure (Severity: High): Prevents unauthorized users from listing all databases, viewing document IDs, or accessing configuration details via CouchDB's API.
  • Unauthorized Data Modification (Severity: High): Prevents unauthorized users from replicating data or making changes to the database configuration through CouchDB's API.
  • Privilege Escalation (Severity: High): Limits the ability of a compromised user account to gain administrative access within CouchDB.
  • Information Disclosure (Severity: Medium): Reduces the risk of leaking sensitive configuration information stored within CouchDB.

Impact:

  • Unintentional Data Exposure: Risk significantly reduced. Unauthorized access to sensitive CouchDB endpoints is blocked.
  • Unauthorized Data Modification: Risk significantly reduced. Only authorized users can perform administrative actions within CouchDB.
  • Privilege Escalation: Risk significantly reduced. Attackers cannot easily gain administrative privileges within CouchDB.
  • Information Disclosure: Risk reduced. Sensitive configuration information within CouchDB is protected.

Currently Implemented: [Placeholder: e.g., "Implemented in the production database security object. Futon/Fauxton are disabled via configuration file settings."]

Missing Implementation: [Placeholder: e.g., "Not yet implemented for the _users database. "]

Mitigation Strategy: Secure Design Document Functions

Description:

  1. Input Validation: Within every design document function (views, shows, lists, update functions, validate_doc_update), rigorously validate and sanitize all user-supplied data. This includes data passed as query parameters, request bodies, or document fields to the CouchDB API. Use type checking, regular expressions, and whitelisting within the JavaScript code of the design documents to ensure data conforms to expected formats.
  2. Avoid eval() and Similar: Never use eval(), Function(), or similar constructs within design document functions. These can execute arbitrary JavaScript code.
  3. validate_doc_update Implementation: Implement a validate_doc_update function in each database (within a design document) to enforce schema validation and prevent unauthorized document modifications. This function should check:
    • Data Types: Ensure fields have the correct data types (string, number, boolean, etc.).
    • Required Fields: Verify that all required fields are present.
    • Allowed Values: Enforce restrictions on allowed values (e.g., using regular expressions or predefined lists).
    • User Permissions: Check if the user attempting the update (available via the userCtx object) has the necessary permissions (roles) as defined in the database's security object.
  4. Code Review: Regularly review the JavaScript code of design documents for potential vulnerabilities, especially in functions that handle user input.
  5. Least Privilege (via Roles): Use different user roles (defined in the database security object) with specific permissions to execute certain design documents or specific views/shows/lists within those design documents. This is achieved by checking the userCtx.roles array within the design document functions.
  6. Use of Libraries: If complex validation is needed, consider using a well-vetted JavaScript validation library within the design document (ensure the library itself is secure and doesn't introduce vulnerabilities). The library code would be included as part of the design document.

Threats Mitigated:

  • Code Injection (Severity: High): Prevents attackers from injecting malicious JavaScript code into design document functions, which are executed by CouchDB.
  • Data Tampering (Severity: High): Prevents unauthorized modification of documents through validate_doc_update, enforced by CouchDB.
  • Cross-Site Scripting (XSS) (Severity: High): If design documents are used to generate HTML output (e.g., in show functions), proper sanitization within the CouchDB design document prevents XSS attacks.
  • Denial of Service (DoS) (Severity: Medium): Prevents attackers from crafting malicious inputs that could cause excessive resource consumption within design document functions executed by CouchDB.

Impact:

  • Code Injection: Risk significantly reduced. Malicious code execution within CouchDB is prevented.
  • Data Tampering: Risk significantly reduced. Document integrity is enforced by CouchDB.
  • XSS: Risk significantly reduced (if applicable). Output generated by CouchDB is properly sanitized.
  • DoS: Risk reduced. Resource exhaustion attacks within CouchDB are mitigated.

Currently Implemented: [Placeholder: e.g., "validate_doc_update functions are implemented in all databases. Basic input validation is performed in view functions."]

Missing Implementation: [Placeholder: e.g., "Comprehensive input validation is missing in some list and show functions. Code review of design documents is not yet a regular process."]

Mitigation Strategy: Secure Replication (CouchDB Configuration)

Description:

  1. HTTPS Encryption: Configure CouchDB to require HTTPS for all replication connections. This involves setting appropriate configuration options in CouchDB's configuration files (local.ini or similar) to enforce TLS. This ensures that data transmitted during replication is encrypted.
  2. Authentication: Configure CouchDB to require authentication for both the source and target databases in replication. This is done by ensuring that both databases have security objects configured and that user accounts with appropriate roles are used for replication. The replication configuration itself (either via the _replicate endpoint or a persistent replication document) must include the credentials.
  3. Filtered Replication (Careful Configuration): If using filtered replication, define the filter functions within a design document in CouchDB. Thoroughly test these filter functions to ensure they behave as expected. A misconfigured filter can lead to data loss or unintended data exposure. Document the filter logic clearly within the design document.
  4. Dedicated Replication User: Create a dedicated user account within CouchDB's _users database with limited permissions specifically for replication. This account should only have the necessary permissions to read from the source and write to the target, as defined in the respective database security objects.
  5. Monitoring (via CouchDB API): Monitor replication status and logs using CouchDB's API (e.g., the _active_tasks endpoint). Look for errors, warnings, or unusual activity.

Threats Mitigated:

  • Data Exfiltration (Severity: High): Prevents unauthorized copying of data to an attacker-controlled server via CouchDB's replication mechanism.
  • Data Tampering (Severity: High): Prevents unauthorized modification of data during replication initiated by or targeting the CouchDB instance.
  • Man-in-the-Middle (MitM) Attacks (Severity: High): HTTPS encryption, enforced by CouchDB's configuration, protects data in transit.
  • Data Loss (Severity: Medium): Careful filter configuration (within CouchDB design documents) and monitoring help prevent accidental data loss.

Impact:

  • Data Exfiltration: Risk significantly reduced. Replication is restricted to authorized servers and users, configured within CouchDB.
  • Data Tampering: Risk significantly reduced. Data integrity is maintained during replication, enforced by CouchDB's configuration and authentication.
  • MitM Attacks: Risk significantly reduced. Data is encrypted in transit, enforced by CouchDB.
  • Data Loss: Risk reduced. Filters are carefully configured within CouchDB and monitored.

Currently Implemented: [Placeholder: e.g., "HTTPS is enforced for all replication connections via CouchDB configuration. Basic password authentication is in place using CouchDB users."]

Missing Implementation: [Placeholder: e.g., "A dedicated replication user account has not been created within CouchDB. Replication monitoring via the CouchDB API is not fully automated."]

Mitigation Strategy: Secure Mango Queries (Within Application Logic Interacting with CouchDB)

Description:

  1. Input Sanitization: Within the application code that interacts with CouchDB, rigorously sanitize and validate all user-supplied data before it is used to construct Mango queries that are sent to CouchDB.
  2. Structured Query Building: Avoid directly embedding user input into Mango query strings within the application code. Instead, construct the query JSON object programmatically, ensuring that user input is treated as data and not as part of the query structure itself. This prevents injection attacks at the CouchDB level.
  3. Limit Query Scope: Avoid overly broad queries that could return excessive amounts of data to the application. Use specific selectors and indexes (defined in CouchDB) to narrow down the results. Avoid using $all unless absolutely necessary.
  4. Avoid Unnecessary Fields: Use the fields option in Mango queries (sent to CouchDB) to retrieve only the necessary fields, reducing the amount of data transferred from CouchDB to the application.
  5. Code Review: Regularly review application code that constructs Mango queries to be sent to CouchDB to identify potential vulnerabilities.

Threats Mitigated:

  • NoSQL Injection (Severity: High): Prevents attackers from manipulating Mango queries sent to CouchDB to retrieve unauthorized data or execute unintended operations on the CouchDB server.
  • Data Exfiltration (Severity: High): Limits the amount of data that can be retrieved from CouchDB through a compromised query.
  • Denial of Service (DoS) (Severity: Medium): Prevents attackers from crafting queries that could cause excessive resource consumption on the CouchDB server.

Impact:

  • NoSQL Injection: Risk significantly reduced. Malicious query manipulation sent to CouchDB is prevented.
  • Data Exfiltration: Risk reduced. The scope of queries sent to CouchDB is limited.
  • DoS: Risk reduced. Resource-intensive queries sent to CouchDB are prevented.

Currently Implemented: [Placeholder: e.g., "Basic input validation is performed before constructing Mango queries in the application."]

Missing Implementation: [Placeholder: e.g., "Structured query building is not consistently implemented in the application. Code review of Mango query construction is not yet a regular process."]