NoSQL Database Access Control: A Practical Guide

Introduction

In the ever-evolving landscape of database technologies, NoSQL databases have become increasingly popular due to their flexibility, scalability, and ability to handle diverse data structures. However, with this flexibility comes the critical challenge of implementing robust access control mechanisms. This article summarizes a comprehensive study on access control implementations across various NoSQL databases and provides detailed insights into common vulnerabilities and their fixes.

Research Overview

The study, available at GitHub Repository, focuses on analyzing and comparing access control mechanisms in popular NoSQL databases. The research aims to provide insights into security models, implementation patterns, and best practices for securing NoSQL database systems.

Key Findings

Access Control Models

NoSQL databases typically implement one or more of the following access control models:

1. Role-Based Access Control (RBAC)

   • Most commonly implemented
   • Provides scalable permission management
   • Easier to maintain in large organizations

2. Attribute-Based Access Control (ABAC)

   • More flexible than RBAC
   • Allows for fine-grained access control
   • Complex to implement and maintain

3. Document-Level Security

   • Specific to document-based NoSQL databases
   • Enables precise control over data access
   • Can be combined with other access control models

Implementation Patterns

Common patterns observed across different NoSQL databases include:

• User authentication mechanisms
• Role hierarchy implementations
• Permission inheritance structures
• Access control list (ACL) implementations

Database-Specific Implementations

MongoDB

• Built-in role-based access control
• Collection-level and document-level security
• Custom roles and privileges
• Enterprise features for advanced security

Cassandra

• Internal authentication and authorization
• Role-based access control
• Resource-based permissions
• Network-level access control

Redis

• Basic authentication
• Access control lists
• Command-level permissions
• Redis ACL system

Vulnerabilities and Fixes in MongoDB and Neo4j

1. Fine-Grained Access Control Problem

MongoDB

Vulnerability: MongoDB provides access control at the database and collection levels but lacks native support for field-level access control. This means users can access entire collections, which may expose sensitive data.

Fix: Implement application-level access control by embedding access policies within documents. This allows for field-level security by specifying which roles can access certain fields.

db.employees.updateMany({}, [
  {
    $set: {
      accessPolicy: {
        salary: { role: ["hrUser"] },  // Only hrUser can see salary
        name: { role: ["hrUser", "regularUser"] },
        department: { role: ["hrUser", "regularUser"] },
        role: { role: ["hrUser"] }
      }
    }
  }
]);

Neo4j

Vulnerability: Neo4j Community Edition does not support fine-grained access control, leading to over-permissioning where users can access more data than intended.

Fix: Implement application-level access control by using role-based access control in the application code.

class EmployeeAccessControl:
    def __init__(self, uri, user, password):
        self.driver = GraphDatabase.driver(uri, auth=(user, password))
    def get_employee_data(self, user_role):
        with self.driver.session() as session:
            if user_role == "Manager":
                result = session.run("""
                    MATCH (e:Employee)-[:HAS_SALARY]->(s:Salary)
                    RETURN e.name, e.role, s.amount
                """)
            else:
                result = session.run("""
                    MATCH (e:Employee)-[:WORKS_IN]->(d:Department)
                    RETURN e.name, e.role, d.name
                """)
            return result

2. NoSQL Injection

MongoDB

Vulnerability: MongoDB is vulnerable to NoSQL injection if user inputs are not properly sanitized. An attacker can manipulate queries to access or modify data.

Fix: Sanitize and validate user inputs before using them in queries. Use regular expressions to ensure only valid inputs are accepted.

def sanitize_input(user_input):
    if re.match("^[a-zA-Z]+$", user_input):  # Only allow alphabetic names
        return user_input
    else:
        raise ValueError("Invalid input: only alphabetic characters allowed")

def secure_find_employee(user_input):
    sanitized_input = sanitize_input(user_input)
    employees = db.employees.find({"name": sanitized_input})
    return list(employees)

Neo4j

Vulnerability: Neo4j is vulnerable to injection attacks if user inputs are directly used in queries without sanitization.

Fix: Use parameterized queries to safely handle user inputs, preventing injection attacks.

class EmployeeSearch:
    def __init__(self, uri, user, password):
        self.driver = GraphDatabase.driver(uri, auth=(user, password))
    def search_employee_by_name(self, user_input):
        with self.driver.session() as session:
            result = session.run(
                "MATCH (e:Employee {name: $name}) RETURN e.name, e.role",
                name=user_input  # Safe parameter binding
            )
            return result

3. Audit Logging

MongoDB

Vulnerability: MongoDB’s audit logging is not enabled by default, which can make it difficult to track database activity and detect unauthorized access.

Fix: Enable profiling to capture all operations, which helps in monitoring and auditing database activities.

use companyDB;
db.setProfilingLevel(2);  // Captures all operations

Neo4j

Vulnerability: Neo4j Community Edition lacks built-in audit logging, making it difficult to track user actions.

Fix: Use Neo4j Enterprise Edition to enable audit logging, which provides detailed logs of database activities.

version: '3'
services:
  neo4j:
    image: neo4j:enterprise
    environment:
      - NEO4J_AUTH=neo4j/password
      - NEO4J_ACCEPT_LICENSE_AGREEMENT=yes
    ports:
      - "7474:7474"
      - "7687:7687"

Configure audit logging in neo4j.conf:

db.logs.query.enabled=INFO
db.logs.query.threshold=0

Best Practices

1. Principle of Least Privilege

   • Grant minimal required permissions
   • Regularly review and revoke unnecessary access

2. Role Management

   • Implement clear role hierarchies
   • Document role assignments and permissions
   • Regular auditing of role assignments

3. Authentication

   • Use strong authentication mechanisms
   • Implement multi-factor authentication where possible
   • Regular credential rotation

4. Monitoring and Auditing

   • Implement comprehensive logging
   • Regular security audits
   • Monitor access patterns

Conclusion

Access control in NoSQL databases requires careful consideration of security requirements, performance implications, and maintenance overhead. As demonstrated in the vulnerability and fix examples, implementing proper access control mechanisms is crucial for protecting sensitive data in NoSQL databases while maintaining their flexibility and performance benefits.

References

1. NoSQL DB Access Control Repository
2. MongoDB Security Documentation
3. Apache Cassandra Security Documentation
4. Redis Security Documentation
5. Neo4j Security Documentation

This article is part of our ongoing series on database security and best practices. For more information, please refer to the original research repository.

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