Preparing a penetration test (pentest) is a complex process that requires careful planning and coordination. A well-planned pentest can not only help to identify security vulnerabilities in IT systems, but also significantly improve an organization’s overall security posture. In this article, we provide you with a detailed checklist for pentest preparation and explain how you can best prepare for a penetration test. We also highlight common challenges and provide practical tips and a guide to implementation.
What is a Penetration Test?
Why is a Penetration Test necessary?
A penetration test (pentest) is not just any routine assessment—it is a critical, ongoing process that should be performed at regular intervals. Software is dynamic, and new libraries and updates are developed every day, particularly those integrated into your company’s systems. Just as people age, software evolves over time, with frequent updates being made to address discovered vulnerabilities. As these vulnerabilities emerge, they must be identified and mitigated promptly. A notable example of such a vulnerability is the Log4J issue in Java’s logging library, which received widespread attention for its security implications.
However, vulnerabilities are not only introduced through libraries. In many cases, the root cause of security flaws lies in the lack of focus on security during the development phase. It is often claimed that there is insufficient time to address security concerns or that developers overlook security altogether. While assigning blame is not productive, companies must prioritize security, even if it requires additional resources. Investing in robust security measures is essential, as the cost of repairing reputational damage far exceeds the expense of conducting a pentest.
Ultimately, the goal of a penetration test is to identify as many critical and non-critical vulnerabilities as possible, mitigating the risk of severe damage. This proactive approach can save significant costs in the long term, as the consequences of a breach can be far more expensive than performing regular penetration tests. It is also important to note that multiple non-critical vulnerabilities can, when combined, create a “kill chain” that leads to a major security incident.
Here are additional reasons why penetration testing is essential:
- Early Detection of Hidden Vulnerabilities: Uncovering vulnerabilities before malicious hackers can exploit them is crucial to preventing breaches.
- Minimizing Error Messages and Downtime: Exploited vulnerabilities can lead to infrastructure downtime, resulting in significant revenue loss. Penetration testing helps reduce the risk of such incidents.
- Protecting Customer and Employee Data: Data breaches erode trust and can lead to legal ramifications. Securing sensitive information is paramount for maintaining business reputation and compliance.
- Reducing Recovery Costs: In the event of a successful attack, restoring infrastructure can be costly, especially if backups are compromised or unavailable. A penetration test helps mitigate the likelihood of such attacks, saving time and resources.
Types of Penetration Tests
Penetration tests can be conducted at three distinct levels, each offering a different approach and scope. These are classified as black-box, grey-box, and white-box tests, as illustrated below:
1. Black-Box Penetration Test: A black-box test simulates a real-world attack scenario where the pentester has no prior knowledge about the system being tested. The focus is on assessing external and internal infrastructures with minimal organizational involvement. The pentester operates as an outsider, aiming to identify critical vulnerabilities and cause as much simulated damage as possible. This type of test is valuable for understanding how an external attacker might exploit weaknesses in a system.
2. Grey-Box Penetration Test: A grey-box test occurs within a defined scope, where the pentester is provided with limited information about the target system. This may include access to certain credentials or partial system knowledge, enabling the pentester to focus on specific aspects of the infrastructure. The advantage of this approach is that it allows for a more targeted investigation, providing the pentester with the opportunity to explore deeper into potential vulnerabilities that may not be apparent during a broader, less focused test.
3. White-Box Penetration Test: The white-box test is the most comprehensive level, where the pentester is granted full access to all relevant internal resources, including source code, documentation, and system architectures. With complete visibility into the system’s structure, the pentester can identify both technical and logical vulnerabilities. For example, a logical vulnerability could allow unauthorized actions, such as making a purchase on a marketplace platform without being logged in as the correct user. This in-depth access enables the pentester to uncover complex issues that may not be easily detected through other types of testing.
Step 1: Inform important employees
Inform the IT department about the upcoming penetration test to avoid unpleasant surprises and ensure readiness. Designate a member of the IT team as the main point of contact for the penetration testers. Ensure that the entire IT team is available and ready to provide the necessary system access and technical support during the test.
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Step 2: Putting together a response team
Form an interdisciplinary response team consisting of members from the IT department, the security department, the business units and the compliance management teams. This team should carefully review and analyze the test results. Ensure that representatives from different areas of the organization – including security, management and compliance – are available to respond to the test results in a timely manner.
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Step 3: Preparation for possible downtimes
Schedule the penetration test during off-peak hours to minimize business disruption. Develop contingency plans and create backups in case critical systems fail during testing. Inform all relevant teams and stakeholders about the test plan and the possibility of interruptions well in advance.
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Step 4: Avoid last-minute security adjustments
Avoid last-minute changes to the systems that are the subject of the penetration test to ensure the accuracy of the test results. Fix known critical issues, such as unpatched software or outdated systems, well in advance of the test date.
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Step 5: Define the objectives of the penetration tests
Clearly define the objectives of the penetration test to ensure that it is both effective and meets the needs of the organization.
- Compliance requirements: Verify that the test meets relevant standards, such as PCI DSS or HIPAA, if required.
- Focus areas: Identify specific systems, services or functions that need special attention.
- Stealth testing: Determine whether the test should include elements of the stealth approach to test how your security team responds to attacks without being notified in advance.
- Sensitive systems: Clarify whether particularly critical systems, such as medical devices or infrastructure components, should be included in the test.
- Pivoting: Determine the extent to which testers should be able to switch between systems (pivoting) when vulnerabilities are identified.
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Step 6: Scope of the penetration test
Define the scope of the penetration test clearly and precisely to ensure effective execution.
- In-scope systems: Create a detailed list of all networks, systems, applications and segments that are part of the test.
- Excluded systems: Specify any systems or networks that are excluded from the test to avoid accidental disruption or data loss.
- Test type: Decide whether a gray box test (with limited insider access) or a black box test (without prior knowledge) should be performed.
- Test environment: Confirm whether the test should take place in a production or staging environment.
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Step 7: Test access and authorizations
Make sure that access to the test systems and the corresponding authorizations are clearly defined to ensure that the penetration test runs smoothly.
- Network access: Specify how the testers will access the network, e.g. via VPN or special user accounts.
- Provided credentials: Ensure appropriate user accounts are provided for the test, including administrative and user-defined access rights.
- Firewall and WAF customizations: Ensure that the testers’ IP addresses are categorized as allowed in your firewall or Web Application Firewall (WAF) to avoid unexpected blocking during the test.
- Third-party systems: If the systems being tested are hosted by a third party, ensure that written permission is obtained to conduct the penetration test during the designated time period.
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Step 8: Preparing web applications and services
Prepare the web applications and services thoroughly to maximize the effectiveness of the penetration test.
- User accounts: Provide at least two user accounts for each relevant role (e.g. for normal users and administrators) to comprehensively test the escalation of rights.
- Administrative access: Make sure that an administrative account is available for the tests to check the full functionality of the applications.
- Test environment: Confirm whether the test will be performed in the production environment or in a test environment and whether the test team has exclusive access to the required resources.
- Web services: Provide project files for SOAP UI or Postman or at least examples of valid service requests (HTTP) to make it easier for the testers to access the web services.
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Step 9: Definition of time restrictions and communication strategies
Define any time constraints for the penetration test to ensure that the test runs smoothly and potential disruptions are minimized.
- Time constraints: Define the business hours and planned downtime within which the test may be conducted.
- Emergency contacts: Designate two emergency contacts (one primary and one backup) who will be available 24/7 during the test to ensure immediate support if needed.
- Secure communication channel: Set up a secure communication channel that enables the exchange of test updates and sensitive information to maintain confidentiality.
- Update frequency: Determine how often and in what format the test team should provide progress reports on the test to ensure transparent communication.
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Step 10: Review and finalize the Rules of Engagement
Define the “Rules of Engagement” (RoE) for the penetration test to ensure that everyone involved has clear guidelines and that critical issues are handled appropriately.
- Instructions for dealing with critical issues: Specify how testers should proceed when critical security issues are discovered, for example by immediately notifying the responsible contacts.
- Use of exploit code: Ensure that only stable and proven exploit code is used during testing to avoid undesirable effects on systems.
- Handling sensitive data: If sensitive data is discovered, testers must be careful to extract only as much information as is absolutely necessary to demonstrate the risk without jeopardizing the confidentiality of the data.
- Documentation of exceptions: Keep a written record of any exceptions to the standard rules of engagement to avoid misunderstandings and make the test transparent.
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