How Often Should a Penetration Test Be Conducted?

One of the most common questions asked by organizations that conduct penetration tests is how often the tests should be repeated. Many organizations believe that conducting a penetration test just once is sufficient. However, IT infrastructures are constantly changing, new software is being deployed, security patches are being released, and new attack techniques emerge every day.

For this reason, penetration testing should not be viewed as a one-time security activity but rather as an integral part of an organization’s ongoing cybersecurity strategy.

A professional penetration test measures the current security level at a specific point in time. However, this does not mean that the same systems will maintain the same security level six months or a year later. A newly developed module, a misconfigured server, outdated software, or third-party integrations can create new security risks.

What Is the Generally Accepted Practice?

In line with international best practices and industry experience, it is recommended that organizations conduct a comprehensive penetration test at least once a year.

However, an annual test may not be sufficient in the following situations:

• The launch of a new web application
• Major version updates
• Infrastructure changes
• Cloud migration projects
• Deployment of new API services
• Mergers or acquisitions
• Discovery of critical security vulnerabilities
• Cyberattacks or data breaches

Following such changes, it is recommended to conduct penetration testing for the relevant systems rather than simply waiting for the scheduled testing cycle.

Recommended Testing Frequencies for Different Systems

Not all information systems have the same risk level. Therefore, testing frequency should be planned according to the system’s criticality.

System	Recommended Testing Frequency
Web Applications	At least once a year and after major version updates
API Services	After a new release or major changes
Mobile Applications	Before and after major version releases
Internal Network	At least once a year
External Network	At least once a year
Active Directory	Once a year or when significant infrastructure changes occur
Cloud Environments	After architectural changes and at regular intervals
Wireless Network	At least once a year

This table serves as a general guide. More frequent testing may be required depending on the organization’s line of business, regulations, and risk profile.

What Do Regulations Say About Penetration Testing?

Many national and international standards require organizations to regularly validate their technical security controls. However, not every regulation mandates the same frequency.

For example:

PCI DSS

requires organizations that process payment card data to conduct penetration testing at least once a year and after significant changes to their infrastructure.

ISO/IEC 27001

Does not specify a particular frequency. It requires that technical security controls be regularly reviewed and validated based on the organization’s risk assessment.

KVKK

It requires the regular assessment of the effectiveness of technical and administrative measures for the protection of personal data. Penetration testing is one of the methods commonly used in these assessments.

DORA

Requires risk-based security testing and the regular assessment of critical systems for organizations in the financial sector.

NIS2

It requires organizations operating in critical sectors to conduct appropriate technical security tests on a regular basis.

A Real-Life Scenario

An e-commerce company conducted a comprehensive web application penetration test in 2025 and addressed all critical security vulnerabilities.

Six months later, the payment infrastructure was changed, a new campaign module was developed, and a third-party shipping integration was added.

Relying on the previous penetration test, the company did not commission an additional security assessment for the new version.

Shortly thereafter, a lack of authorization controls was detected in the newly added API service, allowing unauthorized access to customer order information.

The investigation revealed that the vulnerability was not in the legacy systems but in the module developed later.

This example demonstrates that security must encompass not only the existing system but also the constantly evolving digital infrastructure.

Continuous Security Approach

Today, mature cybersecurity programs treat penetration testing not as a one-time project, but as part of a continuous improvement cycle.

Thanks to this approach:

• New risks are identified early.
• The effectiveness of security investments is validated.
• Compliance with regulations is facilitated.
• Business continuity is supported.
• Potential data breaches are prevented.

Penetration tests conducted at regular intervals help organizations adapt to the evolving threat landscape and sustainably improve their security posture.

For organizations, it is just as important to determine how frequently penetration tests should be conducted as it is to identify which standards and regulations require or recommend these tests.