Does a Company need Both External vs. Internal Penetration Tests? A Three-Part Practical Guide for CIOs

Does a Company need Both External vs. Internal Penetration Tests?

For many companies, yes.

An external penetration test evaluates what an attacker can see and potentially exploit from outside your company. This can include public IP addresses, VPN gateways, cloud infrastructure, remote access systems, internet-facing applications, and other externally accessible services.

An internal penetration test asks a different question:

What could an attacker do after they get inside?

That foothold could come from phishing, stolen credentials, a compromised workstation, a malicious insider, or another successful initial attack.

The tester may attempt to identify opportunities for lateral movement, privilege escalation, access to sensitive data, and broader compromise.

Here’s an easy way to think about it:

An external penetration test evaluates whether someone can get through the front door.

An internal penetration test evaluates what they could do once they’re inside the building.

Both types of testing are important.

How Often Should Web Applications Be Penetration Tested?

For most important web applications, testing at least once a year is a good place to start in determining how often a web application should be tested.

However, you should also test after big releases, major new features, changes to authentication, new API connections, infrastructure updates, or anything else that could affect security.

This is particularly important for custom applications.

Automated security tools can identify many known weaknesses, but they often struggle to identify complex authorization problems and business logic vulnerabilities.

A web application may have no obvious critical vulnerability when scanned automatically while still allowing a user to manipulate workflows or access information they should never be able to see.

Manual penetration testing provides another layer of assurance.

How Often Should You Test Cloud Environments?

You should check your cloud environments regularly and after any big changes.

A company using AWS or Azure may add and remove resources every week. New permissions may be assigned. Storage settings may change. New APIs and applications may be deployed.

The tricky part is that cloud environments can change much faster than traditional systems.

Instead of testing every cloud resource on a set schedule, CIOs should mix regular checks with extra tests after important changes.

Major cloud migrations, significant architecture changes, new internet-facing services, and changes to identity or access permissions are all events that may justify additional testing.

What Is the Difference Between a Penetration Test and a Vulnerability Assessment?

This matters when you’re planning your cybersecurity budget.

A vulnerability assessment identifies known weaknesses, typically through automated scans.

A penetration test goes further by using manual methods to see whether attackers could exploit those weaknesses and what damage they could cause.

We think the two in practical terms: vulnerability assessments help identify known weaknesses, while penetration testing evaluates whether those weaknesses can be exploited and how they could affect the business.

Most companies get value from doing both types of tests.

A good approach is to conduct vulnerability assessments more often (every month or quarter, depending on your risk level) and add penetration testing periodically to see how exposed you really are.

Think of vulnerability management as your regular check-up for problems.

Penetration testing is like bringing in an expert to see if those problems could actually let someone break in.

What Does a Penetration Test Cost?

The cost of penetration testing depends a lot on how much you want to test.

A small external penetration test may require substantially less time than a comprehensive assessment involving multiple networks, cloud environments, web applications, APIs, authenticated user roles, and internal testing.

The biggest factors typically include the number of systems in scope, application complexity, cloud infrastructure, number of user roles, testing methodology, compliance requirements, and whether social engineering or other specialized testing is included.

For CIOs, the key budgeting decision isn’t just picking the cheapest option.

It is ensuring the scope matches the business risk.

A cheap penetration test that only looks at a small part of your environment may not help much. On the other hand, testing everything the same way can waste money.

The best approach is usually to focus your testing on the areas with the most risk.

Test the systems where a breach would hurt your business the most.

Tanner Security also recommends prioritizing high-risk systems first and aligning testing scope with the systems and changes that matter most to the business.

How CIOs Can Get More Value From Penetration Testing

The value of a penetration test depends on what happens after the final report is delivered.

A report should not become another document that sits in a shared folder until the next audit.

CIOs should use the results to answer practical questions.

Which findings create the greatest business risk?

Who owns remediation?

What can be fixed immediately?

Which issues require budget or architectural changes?

Are the findings recurring from previous assessments?

Should significant vulnerabilities be retested?

This is where working with an experienced testing partner can really help.

Technical teams need enough detail to fix problems, while leadership needs to know the business impact and what to fix first.

These are different audiences, so your reports should help both groups.

Tanner Security focuses on providing you with clear, actionable reports and helping your IT team verify that fixes actually work.

A Simple Decision Framework for CIOs

If you’re not sure whether it’s time for another penetration test, ask yourself these questions:

“Has it been more than 12 months since our last comprehensive test?”

“Have we launched a new business-critical application or significantly changed an existing one?”

“Have we migrated important systems to the cloud?”

“Have we changed our identity, authentication, or remote access environment?”

“Have we completed an acquisition or integrated another company’s systems?”

“Have we experienced a cybersecurity incident?”

“Have we added systems that process more sensitive data?’

“Do customers, regulators, insurers, or contracts require current testing?”

If you answered yes to any of these, it’s probably time for more testing.

Does a Company need Both External vs. Internal Penetration Tests FAQ

Does my company need both internal and external penetration testing?
For many companies, yes. External penetration testing evaluates whether attackers can exploit systems accessible from the internet, while internal penetration testing evaluates what an attacker could do after gaining access to the internal environment. Together, they provide a more complete picture of your company’s exposure.

What is the difference between internal and external penetration testing?
External penetration testing focuses on attack paths available from outside the company, such as public-facing applications, VPNs, firewalls, cloud services, and remote access systems. Internal penetration testing assumes an attacker has already gained some level of access and evaluates potential lateral movement, privilege escalation, and access to sensitive systems or data.

How often should a company perform a penetration test?
For many companies, a comprehensive penetration test at least once a year is a reasonable starting point. Additional testing may be appropriate after major technology changes, application releases, cloud migrations, security incidents, acquisitions, or significant changes to identity and remote access systems.

How often should web applications be penetration tested?
Important web applications should generally be penetration tested at least annually and after significant changes. Major releases, new functionality, authentication changes, API integrations, infrastructure changes, and substantial modifications to business logic can all justify additional testing.

How often should cloud environments be tested?
Cloud environments should be assessed regularly and after significant changes. Because AWS, Azure, and other cloud environments can change rapidly, companies should combine routine security assessments with targeted penetration testing after major architecture changes, new internet-facing services, cloud migrations, or significant identity and access changes.

Can a vulnerability assessment replace a penetration test?
No. A vulnerability assessment and penetration test serve different purposes. Vulnerability assessments identify known weaknesses, while penetration testing uses manual techniques to determine whether vulnerabilities or configuration weaknesses can be exploited and what an attacker could accomplish. Most companies benefit from using both.

How often should vulnerability assessments be performed compared with penetration tests?
Vulnerability assessments are typically performed more frequently because they can help identify newly discovered vulnerabilities as the environment changes. Depending on the company’s risk profile, vulnerability scanning may occur monthly, quarterly, or continuously, while penetration testing is generally performed periodically and after significant changes.

How much does a penetration test cost?
Penetration testing costs vary considerably depending on the scope and complexity of the engagement. Factors include the number of systems, applications, IP addresses, cloud environments, user roles, APIs, authentication methods, compliance requirements, and whether internal, external, web application, or specialized testing is included. The right scope should be based on business risk rather than simply choosing the lowest-cost test.

What should be included in a penetration test?
The scope should reflect the systems and attack paths that present the greatest risk to the company. Depending on the environment, this could include external infrastructure, internal networks, web applications, APIs, cloud environments, authentication systems, remote access, and privileged accounts. A penetration testing provider should help define an appropriate scope before testing begins.

What happens after a penetration test is completed?
The penetration test should result in a detailed report identifying vulnerabilities, attack paths, potential business impact, and remediation recommendations. Your IT team should prioritize the findings based on risk, assign responsibility for remediation, and address significant weaknesses. Critical findings should also be retested when appropriate to confirm that the vulnerabilities have been successfully resolved.

Should a company perform penetration testing after a cybersecurity incident?
It can be an important part of post-incident security validation. Penetration testing can help determine whether weaknesses related to the incident remain exploitable and whether other attack paths could lead to similar compromise. It should complement, rather than replace, forensic investigation and incident response activities.

What should a CIO consider when deciding whether it is time for another penetration test?
A CIO should consider how long it has been since the last test, how significantly the technology environment has changed, whether new applications or cloud services have been deployed, whether identity and remote access controls have changed, whether the company has experienced an incident, and whether customers, regulators, insurers, or contracts require current testing. If several of these conditions apply, additional penetration testing is likely warranted.

Is penetration testing required for compliance?
Some regulatory frameworks, contractual requirements, and security standards may require or strongly recommend penetration testing, but the specific requirements depend on the company, industry, systems, and applicable framework. Companies should evaluate their individual compliance obligations rather than assuming that one annual penetration test satisfies every requirement.

How do I know whether my company needs an internal, external, or web application penetration test?
The answer depends on where your greatest exposure exists. Companies with significant internet-facing infrastructure may prioritize external testing. Those concerned about what could happen after a workstation or account is compromised may need internal testing. Companies that develop or operate customer-facing applications should strongly consider web application testing. Many companies benefit from combining multiple testing types.

What makes a penetration test valuable to a CIO?
A valuable penetration test does more than produce a list of technical vulnerabilities. It should help leadership understand which weaknesses create meaningful business risk, what an attacker could realistically accomplish, which issues should be addressed first, and whether remediation reduced the risk. The goal is to turn technical testing into actionable information that supports security and business decisions.

Penetration Testing Frequency Related Services

• External Network Penetration Testing: Evaluate your company’s internet-facing systems from the perspective of an external attacker. Testing may include public infrastructure, VPNs, remote access systems, cloud services, and other externally accessible assets. Tanner Security recommends annual testing and additional testing after significant changes.
• Internal Network Penetration Testing: Determine what an attacker could accomplish after gaining an initial foothold inside your network.
• Web Application Penetration Testing: Evaluate business-critical web applications for vulnerabilities involving authentication, authorization, session management, input validation, APIs, and business logic.
• Custom Application Penetration Testing: Assess proprietary applications with complex workflows, integrations, user roles, and functionality that may require deeper manual testing.
• Cloud Penetration Testing: Test AWS, Azure, and other cloud environments for exploitable weaknesses and misconfigurations.
• Vulnerability Assessments: Identify known vulnerabilities more frequently and use the results to support ongoing remediation between penetration testing engagements.
• Cybersecurity Risk Assessments: Evaluate the broader cybersecurity program and identify which systems, threats, and weaknesses should receive the highest priority.