Penetration testing best practices are essential for effective and consistent testing. By adhering to established guidelines and methodologies, businesses can systematically uncover potential security threats, mitigate risks, and protect sensitive data.

General penetration testing best practices

The overall best practices for penetration testing start with clearly defining your scope and goals. Next, determine your budget, because costs vary based on the test type and complexity. Other best practices include choosing the right vendor, methodologies and tools.

The following best practices apply to all types of pen testing:

• Define the scope
  Defining the scope establishes clear boundaries by outlining specific test objectives and conditions. It answers critical questions such as: Are we aiming to enhance security or ensure compliance? What is the target environment? Which systems, networks, and assets need testing?

Brad Herring, VP of business development at Raxis, says, “It’s important to verify the scope. Sometimes a customer wants to test a system, but we realize the company doesn’t own it, and it would be illegal for us to do so.” 

Brian Tant, chief penetration testing officer at Raxis, agrees. "Testing outside the defined scope exposes the company to potential liability." Therefore, defining a precise scope is essential to managing risks during testing.

• Understand the objectives
  Understanding objectives narrows the testing focus, which saves time and supports customer satisfaction. For example, Herring recently engaged in a physical penetration test where the customer specified precise limitations: no testing of clean desk policies, no attempts to access offices, and no wireless testing. Their sole objective was to breach a specific door and access the devices beyond it. This focused approach streamlined the testing process, aligning directly with the client's needs.

• Establish a budget
  The cost of penetration testing varies significantly. The budget affects the type of testing, the amount of time it takes to conduct, and the coverage focus. When setting a budget, consider your objectives, needs, and the value of your assets.

• Follow laws and permissions
  Always obtain consent from system owners and stakeholders before conducting penetration testing to ensure compliance with laws and regulations. Testing systems without proper ownership or authorization can lead to legal repercussions. Additionally, it is essential to safeguard confidential data against unauthorized access or disclosure during testing. 

• Follow a methodology
  Choose methodologies based on the organization's industry, assets, and specific security requirements and qualifications. Consider how the methodology aligns with the objectives, and tailor the approach to address the vulnerabilities and risks relevant to the environment.
  
  Common pen testing methodologies use the following frameworks and resources: 

• • MITRE ATT&CK – A knowledge base of real-world cyberattack techniques.
  • Penetration Testing Execution Standard (PTES) – A comprehensive framework providing guidelines for all phases of penetration testing. 
  • Open-Source Security Testing Methodology Manual (OSSTMM) – A peer-reviewed methodology focusing on operational security, providing a scientific approach to security testing and analysis.
  • Open Web Application Security Project (OWASP) – A set of principles and best practices for web application security, including tools, documentation, and forums to address common vulnerabilities like XSS and SQL injection.

• • National Institute of Standards and Technology (NIST) – A widely recognized set of guidelines and standards for cybersecurity.
  • Information System Security Assessment Framework (ISAFF) – A methodology designed to help organizations assess their information systems' security posture.

• Use scanning tools
  Automatic scanning tools save time and resources. 

Stephen Ferrell, chief strategy officer at Strike Graph, says, “Scanning tools do the heavy lifting of the pen test.” They look for what services are running, potential vulnerabilities, if there are any open ports, etc. Following the scan, a security analyst assesses the information. 

• Choose a qualified tester
  Selecting a penetration tester hinges on trust and building a solid relationship. For emerging companies, Ferrell advises evaluating the tester's expertise and specialization in specific fields like government or healthcare. Their capabilities should align with the field and the sensitivity of the tested information.
  
  “It’s hard to discern one tester from another because the shop windows are similar,” Ferrell says. He recommends getting a tester on a call to learn their familiarity with testing in the industry and request they provide references from their customers. 
  
  

• Prepare the test environment
  Prepare the environment, obtain any necessary authorizations, and identify team members to review the test report and fix issues discovered during the test. Prepare to act quickly if a high-risk vulnerability is discovered. Establish monitoring solutions before starting the pen test so you can take action when necessary. Maintain transparency by informing all stakeholders about the penetration testing activities.
• Respond to vulnerabilities
  Review the post-testing results and follow proper incident response protocols and recommendations for handling vulnerabilities discovered during the test. Contain the issue, eliminate the threat, and recover from the incident to prevent future occurrences. 
• Plan and implement remediation
  Identify the root cause of each vulnerability and develop corrective strategies. Tant and Herring strongly recommend correcting vulnerabilities as soon as possible. If not fixed within 7-8 months, these vulnerabilities persist and coincide with the next annual pen test.
  
  After remediation, re-evaluate security measures to ensure the vulnerabilities have been fully resolved. Regularly review and update pen testing procedures and methodologies to adapt to evolving threats and technological changes. Learn from each test to enhance the overall security posture, maintaining open communication for feedback and addressing any questions or concerns.
  
  

External penetration testing best practices

External penetration testing evaluates system security from an external perspective to identify vulnerabilities that outside attackers could exploit.

• Conduct comprehensive reconnaissance
  Gather extensive information about the target through passive means (e.g., WHOIS lookup, DNS enumeration) and active means (e.g., port scanning, service enumeration). This helps identify the attack surface and potential entry points. Keep detailed records of all discovered assets, services, and vulnerabilities to ensure a thorough analysis and facilitate effective remediation.
• Use a variety of testing tools and techniques
  Use a combination of automated tools for initial scanning and manual testing to validate findings and uncover hidden vulnerabilities. Employ a range of tools, such as vulnerability scanners, exploit frameworks, and custom scripts, to identify and exploit different vulnerabilities, ensuring a comprehensive assessment of the target.

Internal penetration testing best practices

Internal penetration testing targets the internal network and systems, simulating insider threats and identifying vulnerabilities that could be exploited within the organization.

• Ensure objectivity
  Approach internal penetration testing with an unbiased mindset, simulating an attacker without prior knowledge of the internal network. Avoid relying on inside information that could skew the test results, and strive to identify vulnerabilities and weaknesses as an external attacker would, ensuring a realistic assessment of the internal security posture.
• Manage access controls
  Coordinate with the organization’s IT or security team to gather the necessary access credentials, such as passwords and logins, required for the testing process. Properly managing access controls allows testers to evaluate the effectiveness of current access management policies and identify potential weaknesses in user permissions and role-based access controls.
• Clean up artifacts
  After completing the testing, thoroughly remove any tools, scripts, or accounts created during the penetration test. Cleaning up artifacts ensures that malicious actors can exploit no residual elements and helps maintain the integrity and security of the internal network. Document the cleanup process to record actions taken during the test.

Web application penetration testing best practices

Web application penetration testing aims to identify and address security weaknesses in web applications to prevent attacks such as XSS, SQL injection, and other common vulnerabilities.

“Web application pen testing involves more perimeter tampering and business logic testing,” Tant says.

• Use the open web application security project (OWASP) methodology
  This framework provides lists of the most common cyber threats as well as tools, forums, and documentation. It focuses on vulnerabilities such as cross-site scripting (XSS), SQL injection, and remote code execution and helps organizations stay informed about emerging threats.
• Total and thorough enumeration of parameters and endpoints
  Thorough enumeration helps identify potential attack vectors and ensures that no aspect of the application is overlooked during the testing process.
• Continuously test the code
  Continuous testing helps ensure that security is maintained as new features are added and changes are made to the codebase.

Mobile application penetration testing best practices

Mobile application penetration testing focuses on identifying and mitigating security vulnerabilities in mobile apps across different devices and operating systems.

• Use the open web application security project (OWASP) methodology
  This framework provides lists of the most common cyber threats as well as tools, forums, and documentation. It focuses on vulnerabilities such as cross-site scripting (XSS), SQL injection, and remote code execution and helps organizations stay informed about emerging threats.
• Use static analysis and dynamic analysis
  Static analysis helps find issues early in the development cycle, ensuring they are addressed before deployment. Dynamic analysis provides insights into the application's performance under various conditions and potential attack scenarios.
• Operating system testing for devices
  Test the application on various devices and OS versions to ensure it operates securely across different environments.
  
  

Cybersecurity penetration testing best practices

Effective cybersecurity penetration testing involves systematically identifying, evaluating, and mitigating potential vulnerabilities. 

• Perform regular testing
  Conduct regular penetration testing to keep up with the evolving threat landscape. Frequent tests help identify new vulnerabilities and ensure that previously identified issues have been resolved.
• Incorporate threat intelligence
  Utilize threat intelligence to understand potential attackers' tactics, techniques, and procedures (TTPs). This knowledge allows testers to simulate real-world attack scenarios and identify vulnerabilities that adversaries might exploit.
• Use a risk-based approach
  Prioritize testing efforts based on the risk profile of assets. Focus on high-value and high-risk assets first to promptly identify and address critical vulnerabilities.
• Simulate advanced persistent threats (APTs)
  Include scenarios that mimic advanced persistent threats (APTs) to evaluate the organization's resilience against sophisticated and persistent attackers. This helps us understand how well the defenses can withstand prolonged and targeted attacks.

Cloud penetration testing best practices

Cloud environments present unique challenges and require specific best practices for effective penetration testing.

• Understand the shared responsibility model
  This model clarifies the division of security responsibilities between the cloud provider and the customer, guiding testers on which aspects they are responsible for testing and securing.
• Obtain authorization and consent
  Obtain explicit authorization and consent from the cloud service provider and relevant stakeholders to ensure compliance with legal and contractual obligations.

Social engineering penetration testing best practices

Social engineering penetration testing evaluates the effectiveness of an organization's human defenses by simulating attacks that exploit human behavior.

• Use a variety of techniques
  Use techniques such as pretexting, phishing, smishing, and tailgating.
• Test at various times
  Test at various times to minimize suspicion and get a more accurate picture of the vulnerabilities.

Container penetration testing best practices

Container penetration testing identifies and mitigates vulnerabilities within containerized environments and their underlying infrastructure.

• Validate container and infrastructure security
  Test the running containers and their underlying infrastructures to ensure that vulnerabilities in the container environment and its supporting systems are identified. 
• Assess the entire container lifecycle
  Evaluate the lifecycle from build to runtime to uncover potential vulnerabilities at every stage.
• Reduce your attack surface
  Minimize the number of components in each container and maintain the slimmest profile for all containers.

Physical penetration testing best practices

Physical penetration testing evaluates the effectiveness of physical security measures by attempting to gain unauthorized access to facilities and sensitive areas.

• Obey the law
  Obtain authorization before conducting any test to ensure it is conducted legally and ethically. For example, it’s illegal for pen testers to impersonate a police officer or use a crowbar to break a window. These constraints do not bind hackers, so it’s important to note the vulnerabilities without damaging property. “We’re not going to do something to purposely break something,” Herring explains. 

• Test multiple entry points and methods
  Evaluate security comprehensively by testing various entry points and methods. This includes assessing physical barriers, access controls, and human factors such as social engineering techniques. 

• Use the appropriate tools
  Equip pen testers with specialized tools suitable for the assessment, such as lockpicking tools, bypass devices, RFID readers, and disguises where applicable. Leveraging Open-Source Intelligence (OSINT) can also aid in identifying nearby facilities for potential surveillance or access points.

IoT Penetration Testing Best Practices

IoT penetration testing focuses on identifying and addressing security vulnerabilities specific to Internet of Things (IoT) devices and networks. 

• Use the OWASP IoT Top 10
  Leverage the OWASP IoT Top 10 framework as a foundational guide for IoT penetration testing. This resource highlights the most critical security vulnerabilities specific to IoT devices, providing a comprehensive checklist for identifying and addressing potential threats. 

• Use Secure Protocols and Strong Encryption
  Implement robust encryption methods and secure communication protocols to protect data transfer and maintain the privacy of sensitive information within IoT networks. Assign each device a unique cryptographic credential to ensure secure identity verification and prevent unauthorized access. 

• Define Methods for Decommissioning and Destroying Malfunctioning IoT Devices
  Establishing and implementing secure methods for decommissioning and destroying malfunctioning IoT devices prevents potential data loss or exploitation, even in the case of device failure. Proper decommissioning procedures should include wiping all sensitive data from the device, securely disposing of or recycling hardware components, and ensuring unauthorized parties cannot repurpose or access decommissioned devices. 

Best Practices for Choosing the Right Pen Testing Vendor 

When choosing a penetration testing vendor, you should evaluate key factors through research, interviews, and reference checks. The right vendor will be an expert in your field. They also will provide strong references and authoritative answers to your questions.

• Assess the pen testers' skills and expertise in your field
  Determine their specialized fields and ensure they align with your organization's requirements.

• Verify their credentials
  Verify the certifications held by the pen testers, as these credentials demonstrate their knowledge and commitment to industry standards.

• Request references
  Get references from companies of similar size and scope that have previously used the pen tester's services. This will provide insight into the pen tester's performance and reliability.

• Score the vendors based on your research, interviews and reference checks
  Score each vendor on the criteria most important to you. Add all the scores to determine your winner.
• Interview your vendor candidates with a standard question set
  Ensure you cover the bases with key questions you ask of all your potential vendors. Make sure your chosen vendor has the expertise and experience your company needs.
  
  Download the following list of questions to ask pen-testing vendors.
  • What types of testing do you offer? (Such as external, internal, web application, mobile app, API, wireless network)
  • Where would the testing take place?
  • What would be automated vs. manual?
  • What methods do you use?
  • What is the experience level of the engineer(s)?
  • What certifications do your testers hold?
  • How do you scope a penetration test?
  • What is the timeline for delivering the final report?
  • What measures do you take to protect sensitive information during and after the test?
  • What does your penetration testing report include?
  • Can you explain your reporting process?
  • What is your approach to handling discovered vulnerabilities?
  • Do you offer remediation and other follow-up services?
  • Do you provide a retesting service after remediation?
  • What are your pricing models?
  • Do you offer any guarantees or service-level agreements?
  • How do you handle test disruptions?
  • What level of customization do you offer in your testing services?
  • How often do you recommend we do pen tests?
  • How do you stay updated on security threats and testing methodologies?
  • How do you ensure compliance with relevant regulations and standards?
  • What tools and technologies do you use for testing?
  • What references can you provide from similar industries?
  • What kind of support do you offer during and after testing?
  • Can you outline a typical engagement timeline?

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