Introduction
Vulnerabilities don’t just sit quietly on the bench. They can and will be exploited if left unchecked. Today’s attackers no longer need elite-level skills either. With AI in the mix, exploits can be generated almost instantly.
In 2026, security testing has become a baseline expectation for all organizations. The challenge now is deciding who should perform it, how frequently it should occur, what to focus on, and most importantly, how to ensure the best results?
Simply put, if you have assets worth protecting, you should conduct active, hands-on penetration testing as well as regular vulnerability scans to ensure your internal infrastructure, software, and even your people are not easily vulnerable to exploitation.
One question we are asked all the time is whether organizations should trust their internal team to catch everything, or should external teams be brought in to actively attempt to break defenses?
We stand firm in saying internal testing alone isn’t enough.
We see lots of organizations use internal teams to perform tests. That's great. But perhaps I can convince you why using testers both inside your organization as well as from an independent third party will lead to better results.
Let’s use sports to frame how we look at effective penetration testing strategies.
First Quarter: Internal Testing - Your Starting Lineup
Before we get into why having a third party perform testing, internal testing is still essential, fundamental, and necessary. It is your opening drive toward a strong security program.
Internal penetration testing plays a critical role in:
- Continuous and prompt vulnerability assessment
- Supporting patch management programs
- Improving application security and network security
- Creating discipline and routines that improve security culture
Covering these key areas will get your team moving down the field and develop early momentum against attackers.
When done right, internal testing is like a team building chemistry. Your team understands the playbook, the systems, the architecture, and can move quickly. It also creates discipline. By making this part of the routine, you send the message to everyone that security is critical to the culture of the organization.
Depending on your specific assets and attack surface, some tasks for your internal team may include:
- Using automated vulnerability scanning tools across web apps, code, and networks
- Manual testing of APIs, applications, and systems
- Code reviews
- Cloud/hosting configuration auditing
- Policy development, security awareness training, and other people focused areas of security
But here’s the catch…
Without external validation, you may not know exactly how well your team is actually performing.
You will put points on the board, but without competition, how do you know if you are really winning?
Second Quarter: Fatigue Sets In – Time To Go To The Bench
Relying on an internal team helps build discipline, reinforce good habits, and strengthen the security of your product or network. However, we've noticed in our experience that a few problems start to show up and linger when organizations develop an overreliance on internal teams for testing. Let's talk about them.
Confirmation Bias
Even the most disciplined teams can fall into subtle bias and start to believe their own scouting report:
- “We built it right; secure development best practices were followed”
- “That edge case probably not exploitable.”
- “We’ve already checked that, it is safe.”
It’s human nature. When you’re close to the product, objectivity gets blurry. This creates blind spots in your risk assessment process.
Business Pressure Leads to Cut Corners
Internal testers may be focused on security. But they are often competing with balancing development deadlines, infrastructure changes, and business expectations.
Security testing can become something squeezed between plays instead of a full drive. Depth gets traded for speed, and important gaps can be missed.
Further, an internal penetration testers may have personal concerns such as job security, work-life balance, and avoiding conflict. They may hesitate to challenge production teams or be seen as obstructing business objectives over a security concern.
This is not a shortcoming of your security team. It’s simply human nature and an inherent part of the internal role.
Limited Exposure to Emerging Threats
Even highly skilled internal professionals can get stuck running the same drills. They know their tools well but may not see the latest tactics, techniques, and play styles attackers are using.
This can lead to repeating the same testing approaches while missing new exploit chains and evolving threats.
This can even occur within external teams if they’re not structured with the right balance of skills and expertise. That’s why at ISE we focus on not just hiring skilled assessors, but on building teams with diverse backgrounds, education, and areas of specialization. During the assessment we perform, we encourage analysts with different backgrounds to collaborate, and will often switch primary testers between regular tests. Fresh perspectives are extremely important to get the best possible results.
Third Quarter: External Testing, Let’s Run the Option
An external pen testing team is like bringing in an option QB off the bench. They see the field differently, don't carry the same assumptions, have different skills, and can expose weaknesses your “starter” (internal team) might miss.
Let’s discuss some of the benefits of external pen testing teams.
Advanced Vulnerability Discovery and Exploitation
External testers bring experience from many environments, industries, and systems. They have seen different defenses and know how to break through them in critical workflows within applications and infrastructure (e.g., authentication, access control, cryptography, input handling, etc.).
This expertise isn’t something that is stumbled upon. They do not just run plays; they read the defense like an opponent. They understand how attackers think, what they target, and how small weaknesses can be chained together for a big score.
Your internal team may have solid fundamentals, but external testers bring game reps from across the league. Much like the option QB has a focused skill set, external testers have a security purpose. It is their job to come in, learn a system, and find exploits. They are specialists.
External teams don’t just mix things up. The real value is in bringing adversarial thinking; acting like real attackers, not defenders.
Unbiased Assessment
External assessors are not tied to your internal goals or timelines. Their job is simple: find the gaps and exploit them. In fact, they are incentivized to find vulnerabilities.
Without pressure from release cycles, they can go deeper and test more creatively.
It is like bringing in an outside analyst who studies your team without emotion and calls out every weakness that opponents could use against you.
Fresh Legs, Fresh Eyes, Fresh Perspective
Internal teams might revisit the same code paths repeatedly without seeing the issue. An external tester steps in, reads the field differently, and suddenly the opening is obvious.
That is when vulnerabilities start showing up, from XSS to SQL injection to broken logic and beyond.
An external tester is like a team that's reviewing game film to look for weaknesses in a defense. Ever watch a game and see that an opposing team finds the gaps over and over again and can't be stopped? That's the power of an outside perspective.
Fourth Quarter: Final Moments, Deploy the Crunch Time Lineup
The ultimate strategy is blending players from your internal team and external team because, like a well-balanced football team, bringing the right mix of talent together can have an exponential benefit that is more than the sum of its parts.
Blending internal and external teams isn’t about balance; it’s about situational advantages.
In a Hail Mary situation, you wouldn’t want your normal defensive that is comprised of a normal number of linebackers when you need personnel to defend against deep passes.
Great coaches know when to augment the team.
Internal teams bring continuity, system knowledge, continuous monitoring, and the ability to respond quickly. External teams bring fresh perspective, offensive thinking, real world attack simulation, stress-test assumptions, and tailored remediation guidance.
This means your internal team owns day-to-day monitoring, threat detection, and incident response. They are your defensive core, reading the offense in real time.
Then you rotate in external players with intent:
- When you need to simulate a real adversary, you bring in external pen testers to run full attack scenarios.
- When you’re preparing for a major release or infrastructure change, use them to stress-test what the internal team built.
- Perhaps most importantly, when the stakes are greatest, we want to bring in the best players.
In other words, you don’t just add external resources; you deploy them.
Security is never perfect, but combining both approaches gives you a defense that is hard to break.
The goal is to win, or in other words, limit the probability and maximize how you use the resources and expertise available to you for successful results. Ideally, you want your opponent to quit playing the game because they can’t win.
Final Thoughts: The Game Time Decision
Framing this as internal versus external testing misses the point. This is exactly why so many security strategies fall short. Winning teams don’t choose one. They build a unified cybersecurity framework that leverages the best possible use of resources available to them, no matter where they come from.
If you rely only on internal pen testing, you lose sight of how real attackers actually operate and limit perspective.
If you rely only on external testing, you sacrifice the day-to-day visibility needed to catch issues early.
Either way, you’re leaving gaps, and attackers are counting on them.
The strongest approach isn’t choosing sides. It’s orchestrating everything: automation, internal expertise, and external adversarial testing working together in a structured, repeatable system.
Think back to the option QB. You don’t deploy that weapon randomly. Used strategically, it changes the game. Used as a gimmick, it collapses under pressure. Pen testing is no different. External testing isn’t a one-off exercise. It's a critical component that must be embedded into your broader security program.
Cyber security isn’t a single game but rather an entire season with no offseason. Threats evolve daily, pressure never lets up, and there is no margin for error.
In football, one missed play might cost you yards. In security, one missed gap can end your franchise.
Now that we have shared our perspective, you should think about how this affects your organization’s security strategy. Choosing the right external pen test partner isn’t easy, but it’s critical to getting meaningful results, not just another report. We discussed this topic in depth to identify the right one in this blog.
You’ve made it this far, so you already know what needs to happen next... take action. Let’s hold Nike’s sentiment and apply to security, “Just Do It!”
Want to learn more about security? Want to get our opinion on how you can improve your “security lineup”? Feel free to reach out to the ISE team to discuss your thoughts today.
