How to secure PostgreSQL databases correctly?
| Categories: | PostgreSQL® |
|---|---|
| Tags: | PostgreSQL® Security |
Securing PostgreSQL databases correctly requires a multi-layered approach with robust authentication procedures, regular backups, and continuous monitoring. Effective security combines transport- and storage-level encryption with strict access controls and proactive monitoring. This comprehensive guide answers the most important questions regarding PostgreSQL security for enterprises.
What are the greatest security risks for PostgreSQL databases?
The greatest security risks for PostgreSQL databases include weak authentication, unencrypted data transmission, poorly configured access rights, and missing security updates. Additionally, SQL injection attacks, unsecured network connections, and insufficient monitoring pose serious threats.
Insufficient authentication often results from weak password policies or the use of default credentials. Many installations still use simple passwords or allow user accounts without appropriate authorization. This provides attackers with direct access to sensitive corporate data. PostgreSQL 18 already offers modern and secure options for user authentication with OAuth2.
A lack of encryption during data transmission allows attackers to intercept communication between applications and the database, as login credentials and business data are transmitted in plain text without SSL/TLS encryption. Today, unencrypted data transmission is a clear no-go in the vast majority of scenarios, even in-house. When working in a cloud environment in the broadest sense—including the use of hosting or service providers—strong transport layer encryption is an absolute must-have. At the same time, unencrypted data storage jeopardizes security in the event of physical access to servers.
Missing or incorrect adjustments to the pg_hba.conf file lead to unintended or more extensive access than intended. This is less about permissions for data within the database and more about the ability to connect to the database at all. Additionally, permissions for the actual data within the database are often configured more broadly than necessary, partly due to convenience or historical reasons. These potential problems are further exacerbated by outdated PostgreSQL versions without current security patches.
How to set up secure authentication and access control?
Unfortunately, a common pattern in applications today is still the fact that the software uses only one generic database user, which often receives more rights in the database than it actually needs. Especially with pre-installed systems, this user is configured with publicly known default passwords. This has nothing to do with security.
Note: In practice, the database user is often set up universally to avoid running into connection limits and/or to benefit from connection pooling and similar techniques.
Fundamentally, permissions (authorization) should be handled as little as possible within the application and instead by the database. This allows the application to save a lot of code and only react to denied access. The opposite is "common" today, which undermines effective data protection.
Secure PostgreSQL authentication is based on strong password policies, role-based access controls, and the principle of least privilege. Configure the pg_hba.conf file restrictively and implement multi-factor authentication for administrative access. Every user should only receive the minimum necessary rights.
Start by creating specific database roles for different application areas. Use CREATE ROLE commands to define function-specific roles. For example, reporting applications only require read access, while backup processes require special system rights. Avoid using the superuser account for routine operations.
The pg_hba.conf file controls client authentication and connection methods. Configure this file to allow only specific IP addresses and subnets. Use scram-sha-256 instead of md5 and forbid trust for production environments. Restrict local connections to necessary system users.
Implement strong password policies with extensions such as passwordcheck to enforce complex passwords. Regular auditing and the deactivation of unused roles further increase security.
In contrast, password rotations have been proven not to help with passwords that a human must enter. Here, the BSI and also the NIST have spoken out against regular rotation in current guidelines. It is clearly recommended to rely on other systems such as passkeys via OAuth2, two-factor authentication, or cryptographically secure passwords and passphrases.
For automatically generated, short-lived access to connect automations, for example, it is also possible to create temporary users with associated passwords via Hashicorp Vault and the "PostgreSQL database secrets engine". In this case, the permissions and availability of the accounts are defined in the Vault and are only created as needed and automatically removed again. This technique is often seen particularly in Kubernetes environments. Our Cloud Infra Team will be happy to advise you on this.
Which backup strategies guarantee full data recovery?
Full PostgreSQL data recovery requires at least logical, but ideally physical backups with continuous archiving of Write-Ahead Logs (WAL). Implement automated daily full backups, supplemented by continuous WAL archiving for Point-in-Time Recovery. Test recovery procedures regularly in isolated environments.
When backing up PostgreSQL databases, the 3-2-1 rule generally applies as always. This means that you create 3 copies on 2 different media, with 1 of them being an offsite backup. It is a fatal error if the backup and the database are on the same medium. Such a setup would be a feast for a ransomware attack. Fundamentally, backup media should either not be permanently available on the network or so-called "immutable" backup media should be used—storage media that can only be written to once. This does not necessarily mean optical storage; organizational locks such as an S3 Object Lock are also a viable solution. There are good approaches to solving this through open-source software, but manufacturers of high-quality storage solutions like NetApp also have corresponding offerings.
Backups should also not be performed without integration into monitoring. At the very least, it should be monitored that backups can be carried out as configured. However, a backup that runs "successfully" but afterwards contains only 0 to less than 100 bytes is worthless. Regular restore tests then confirm this status through spot checks.
Backup Methods
Logical backups with pg_dump are excellent for simple data backup and recovery as well as cross-platform compatibility. This method creates SQL commands to reconstruct database structures and content. For large databases, pg_dump offers parallel processing via the --jobs parameter, which can significantly reduce backup times depending on the database structure. It also makes it easy to back up an entire instance, individual databases, only schema data, or only content. However, it also applies that the restore is performed by executing the individual SQL commands. This can take a lot of time, again depending on the structure and size of the database.
Physical backups via pg_basebackup copy the entire database cluster structure at the file system level. This method allows for faster recovery of large databases and supports continuous archiving. However, there is no option to select which data should be backed up. The entire instance, including index data and other binary data in the data directory, is always included.
Combine base backups with WAL archiving for the option of Point-in-Time Recovery, which enables restores accurate to the second. Base backups can also check the integrity of the backed-up data using checksums. However, this only works if the respective instance has been initialized accordingly.
Continuous archiving of WAL files ensures minimal data loss in the event of system failures. Configure archive_mode and archive_command in the postgresql.conf for automatic WAL transfer to secure storage locations. Monitor archiving processes continuously and implement alerts for errors or delays. If you still have a recovery.conf file described in your environment's documentation, it may be worth having the installation and documentation checked by experts. This file was part of PostgreSQL up to and including PostgreSQL 11 and was merged into the postgresql.conf with PostgreSQL 12.
Another method would be the use of pgBackRest. This is a mature backup and restore framework for PostgreSQL that excels over built-in tools, especially with large clusters. This system can also implement compliance with RPO/RTO requirements. It supports full, differential, and incremental backups, parallelization, block-level delta, WAL archiving, encryption, compression (zstd/lz4), integrity checks, and remote/cloud repositories (e.g., S3, Azure Blob, GCS).
In Kubernetes environments, operators such as CloudNativePG or the Zalando Postgres Operator are often used today. These also use tools such as Wal-E or Barman Cloud for backup and recovery and already offer a high level of integration and monitoring.
How to encrypt PostgreSQL data correctly?
PostgreSQL data encryption occurs on three levels: transport encryption with SSL/TLS for network connections, encryption of data at rest at the storage level, and field-based encryption for particularly sensitive information. Configure SSL certificates for secure client-server communication and use file system or partition encryption, such as LUKS, for database files.
SSL/TLS transport encryption protects data during transmission between clients and servers. Enable SSL by setting ssl = on in the postgresql.conf and configure the corresponding certificate files. Use self-signed certificates for development environments and CA-signed certificates for production systems. The pg_hba.conf should mandate hostssl connections for critical applications.
Encryption of data at rest typically occurs at the file system or storage level using tools like LUKS on Linux, BitLocker on Windows, or cloud provider encryption. PostgreSQL itself does not offer integrated encryption for database files without add-ons; therefore, implement encryption below the database layer. This protects against physical access to storage media and data theft in the event of server compromise.
Field-based encryption for highly sensitive data is provided, for example, by the PostgreSQL extension pgcrypto. This extension offers functions for symmetric and asymmetric encryption of individual database fields. Use this for payment data, personal identifiers, or trade secrets, while taking into account the performance impact on search and sort operations. pgcrypto also provides support for various other cryptographic operations such as hashing or salting.
Which monitoring tools detect security incidents early?
Effective PostgreSQL security monitoring combines integrated logging functions with specialized monitoring tools for anomaly detection. Enable detailed logging in the postgresql.conf and use tools like pgAudit for comprehensive audit logging. Implement automated alerting systems for suspicious activities and performance anomalies.
PostgreSQL's integrated logging functions offer comprehensive monitoring capabilities by configuring the log_* parameters. Enable log_connections, log_disconnections, and log_statement for detailed connection and query logging. The log_line_prefix configuration should include timestamps, users, databases, and process IDs to enable effective forensic analysis.
Specialized tools like pgAudit extend standard logging functions with granular audit trails for compliance requirements. This extension logs database access at the object and role level and allows for the tracking of data modifications. Combine pgAudit with log_statement_stats for performance monitoring and the detection of resource-intensive attacks.
Automated monitoring systems such as Prometheus with PostgreSQL Exporter or specialised database monitoring tools detect anomalies in real time. Monitor metrics such as connection count, query performance, memory usage, and unusual access patterns. Implement threshold-based alerts for critical events such as failed authentication attempts or unexpected database access outside business hours.
Please note, however, that with every expansion of logging, the requirements for storage in terms of performance and especially space requirements also increase. Therefore, check very carefully which configurations are essential for you in production and which only offer added value in the development environment, for example. We are happy to support and advise you here.
How to perform regular security updates and maintenance?
Regular PostgreSQL security maintenance includes systematic update cycles, continuous vulnerability assessments, and proactive configuration reviews. Establish monthly minor updates for patches and plan major updates annually after thorough testing. PostgreSQL also has a relatively stable and well-documented release cycle, which makes the work easy to plan even months in advance.
Security patches for PostgreSQL are released regularly and address critical vulnerabilities. Subscribe to the PostgreSQL Announce mailing list for timely notifications about available minor updates and check the updates of the repositories you use for the corresponding packages. Test patches first in development and staging environments before implementing them in production systems. Use maintenance windows for planned updates and have rollback strategies ready.
Continuous configuration reviews identify security gaps caused by changing requirements or configuration drift. If possible, use automation such as Ansible or similar systems to ensure the desired state and to detect local deviations. Alternatively, at the very least, configuration files should be maintained and monitored with version control. Tools for optimizing configuration in terms of performance and security are available but should be used with appropriate caution, as most systems have individual requirements.
Comprehensive security audits should include quarterly external penetration tests, vulnerability scans, and compliance reviews. Professional PostgreSQL support can help meet complex security requirements and optimally protect critical systems. Conduct regular disaster recovery tests and update incident response plans based on new threat situations and business requirements.
How credativ helps with PostgreSQL security
credativ offers comprehensive PostgreSQL security solutions that cover all critical aspects of database security. Our experts support you in implementing robust security strategies and ensure optimal protection for your company data:
• Security audits and penetration tests: Comprehensive analysis of your PostgreSQL infrastructure to identify vulnerabilities and compliance gaps
• Backup and recovery strategies: Development and implementation of tailored backup concepts with automated monitoring and regular recovery tests
• Encryption implementation: Configuration of SSL/TLS, file system encryption, and column-based encryption according to industry standards
• Monitoring and alerting: Setup of professional monitoring systems with 24/7 support for critical security incidents
• Compliance support: Consulting on meeting GDPR, ISO 27001, and industry-specific security requirements
Secure your PostgreSQL databases with professional expertise. Contact us for an initial consultation and find out how we can optimally protect your database infrastructure.
Securing PostgreSQL databases requires a systematic approach with multiple layers of protection. By implementing robust authentication, comprehensive backup strategies, and continuous monitoring, you create a solid foundation for protecting your corporate data. Regular maintenance and proactive security measures ensure secure and reliable database operations in the long term.
PostgreSQL is an important building block for digital sovereignty. But even this building block requires a little effort and attention to be used effectively. We are happy to support you in the implementation as well as in the training of your IT team.
We are also happy to advise you on other topics related to Linux hardening, for example using AppArmor.
| Categories: | PostgreSQL® |
|---|---|
| Tags: | PostgreSQL® Security |
About the author
Peter Dreuw
Head of Sales & Marketing
about the person
Peter Dreuw arbeitet seit 2016 für die credativ GmbH und ist seit 2017 Teamleiter. Seit 2021 ist er Teil des Management-Teams als VP Services der Instaclustr. Mit der Übernahme durch die NetApp wurde seine neue Rolle "Senior Manager Open Source Professional Services". Im Rahmen der Ausgründung wurde er Mitglied der Geschäftsleitung als Prokurist. Sein Aufgabenfeld ist die Leitung des Vertriebs und des Marketings. Er ist Linux-Nutzer der ersten Stunden und betreibt Linux-Systeme seit Kernel 0.97. Trotz umfangreicher Erfahrung im operativen Bereich ist er leidenschaftlicher Softwareentwickler und kennt sich auch mit hardwarenahen Systemen gut aus.
