database-security

name	database-security
description	Enforce database security for schema design, access control, encryption, and operational hardening. Use when building, reviewing, or auditing database schemas, connection handling, credential management, or database deployment configuration.
category	secure_development
subcategory	cloud-infrastructure

Database Security

Design

Encryption

• Encrypt all communication with the database (TLS in transit)
• Encrypt the database at rest (filesystem, tablespace, or application-level encryption)

Auditing

• Enable database auditing to log accesses and configuration changes
• Audit logs should capture authentication events, privilege changes, and data access patterns

Data Integrity

• Separate test databases from production databases; never share credentials between environments
• Back up data regularly and document the backup and restore process
• Use polyinstantiation to provide multiple views of the same object, preventing unauthorized users from inferring sensitive data
• Apply database normalization to reduce data redundancy and improve integrity
• Implement triggers to enforce referential integrity, prevent invalid operations, and apply complex security rules

Implementation

Least-Privilege Access

• Applications MUST connect with the lowest possible level of privilege
• Use different credentials for every trust level (regular user, read-only user, guest, administrator)
• Users and applications MUST use separate accounts; never share authentication between them

Credential Management

• Use secure credentials for all database access
• Never hardcode connection strings in application code; store them in a separate configuration file on a trusted system, encrypted
• Rotate credentials regularly

Configuration

Default Hardening

• Remove or change all default administrative passwords; use strong passphrases or MFA
• Turn off all unnecessary database functionality (stored procedures, utility packages, unnecessary services)
• Remove default vendor content (sample schemas, example databases)
• Install only the minimum set of features and options required (surface area reduction)

Backend Isolation

• Isolate database servers from other systems and limit host connections
• Disable network (TCP) access when possible; use local socket files or named pipes
• Configure database to bind only on localhost when remote access is not required
• Restrict network port access to specific hosts with firewall rules
• Place database server in separate DMZ isolated from application server
• Never allow direct connections from thick clients to backend database

Transport Layer Security

• Use TLS 1.2+ with modern ciphers (AES-GCM, ChaCha20) for client connections
• Verify digital certificate validity in client applications
• Ensure all database traffic is encrypted, not just initial authentication

Platform-Specific Hardening

• SQL Server: Disable xp_cmdshell, CLR execution, SQL Browser service, Mixed Mode Authentication (unless required)
• MySQL/MariaDB: Run mysql_secure_installation, disable FILE privilege for users
• PostgreSQL: Follow PostgreSQL security documentation guidelines
• MongoDB: Implement MongoDB security checklist requirements
• Redis: Follow Redis security guide recommendations

Implementation Checklist

• All database connections use TLS encryption
• Database storage is encrypted at rest
• Auditing is enabled for access and configuration changes
• Test and production databases are separated with distinct credentials
• Backups are performed regularly with a documented restore process
• Applications use the lowest-privilege database account
• Different credentials are used per trust level (user, admin, readonly)
• Connection strings are not hardcoded; they are stored encrypted on a trusted system
• Default administrative passwords are changed
• Unnecessary features, stored procedures, and sample schemas are removed
• User accounts and application accounts are separate
• Database isolated in separate network segment; no direct thick-client connections
• Platform-specific hardening applied (see above)
• Transaction logs stored on separate disk from main database files
• Encrypted backups with tested restore procedures

References

• Polyinstantiation
• Solutions to the polyinstantiation problem
• Database normalization