What is the difference between internal penetration testing and external penetration testing? | Cyber Security

The majority of penetration tests fall into one of two categories:

  • External penetration testing tries to exploit flaws from outside the company, simulating the types of attacks that remote hackers would carry out on assets that are exposed to the public.  This includes web applications, website servers, open APIs, DNS infrastructure, and other internet-facing systems.
  • Internal penetration testing takes a different approach, simulating the effects of an insider attack.  The target is usually the same as for external pen-testing, but the key difference is that the “attacker” has either authorized access or is starting from within the internal network.  Insider attacks have the potential to be far more devastating than external attacks because insiders already know what’s important within a network and where it’s located, which external attackers usually don’t know from the start.

Internal Penetration Testing:  What you need to know

Without adequate security, your company could be easily hacked, resulting in anything from a minor annoyance to a major breach that threatens your operations and bottom line. Unauthorized individuals gaining access to systems and data is concerning, but the insider attack is far more dangerous. Insiders may be given permission to work around all security measures in order to complete their daily tasks. Because insiders are authorized users of their financial institution’s networks and systems, sophisticated technical skills aren’t always required to carry out an insider attack. Technically skilled insiders, on the other hand, are capable of carrying out more sophisticated attacks that can have a more immediate and widespread impact on financial institutions.

Internal penetration testing (also called internal assessments) uses these techniques on systems, servers, and applications within the confines of your internal network, usually within the public-private boundary created by an external-facing firewall. Many successful attacks against an organization come from within the network boundary, making internal network penetration testing all the more critical. While most organizations initially think of defending their sensitive data and systems from external attacks, many successful attacks against an organization come from within the network boundary, making internal network penetration testing all the more critical. Viruses brought in on mobile devices or removable media, an internal employee committing fraud by exceeding their assigned privileges, or a full-fledged attack from a malicious visitor are all examples of these types of attacks (such as a hacker compromising an internal wireless network or a rogue consultant).

Internal Penetration Points:

  • Switches
  • Directory Servers Routers (Active Directory, LDAP, Novell)
  • Infrastructure services at the core (DNS, DHCP, WINS)
  • Services for File and Print Sharing
  • Workstations for Users
  • Servers for databases
  • Client-Server Applications for Internal Use
  • Web Applications for Internal Use

External Penetration Testing

An engagement designed to evaluate your organization’s perimeter systems from the standpoint of an attacker who has never accessed your network or systems before.  It’s used to see how far a potential attacker can get into your network before being blocked or detected.

Examples of external penetration tests include:

  • Management of Configuration and Deployment Identity Management Testing, Authentication Testing, Authorization Testing, Session Management Testing, and Input Validation Testing are all examples of identity management testing.
  • Weak Cryptography is being tested.
  • Testing for Business Logic
  • Testing on the client side
  • Error Handling is being tested.

Is an external network penetration test right for you?

If you’re in charge of your external network, you should consider the following:

  • Are my systems patched and configured correctly?
  • Are there any systems or applications that use default or weak passwords?
  • Have I considered all of the services that are accessible via the Internet?
  • Is it possible that malware is present on my computer?
  • Is every device protected by a firewall that has been properly configured?
  • Is my private information properly separated or protected?

The Advantages Of External Pen Tests

This type of security evaluation simulates remote cyberattacks aimed at gaining access to a company’s internal computer network.  Penetration testing finds exploitable flaws in web applications, such as exposed servers and users, and verifies firewall protections.  The knowledge gained aids in the improvement of security policies and the patching of vulnerabilities.


Penetration testing, both external and internal, is critical to an organization’s security.  Taking the time and effort to perform a test to help identify exploitable flaws within the network, whether conducted by an internal team or a third-party company like RedLegg, will pay off in the long run for the organization’s security posture.  Ignoring this crucial aspect of a healthy security program could result in not knowing whether an attacker can successfully attack the organization at best, and failing to detect a flaw that could lead to a breach at worst.

One thought on “What is the difference between internal penetration testing and external penetration testing? | Cyber Security

  1. arti says:

    With internal penetration testing, either the device used for the penetration test or the penetration tester is directly connected to the manufacturer’s or producer’s facility network. Internal penetration testing focuses on the vulnerabilities that affect devices on a local network level if one device on the network is compromised, such as an attacker connecting to a computer in accounting. With external penetration testing, the goal for the pen tester is to gain access to the internal network of the business by exploiting external resources, such as company login portals, devices with remote access capabilities accessible to the Internet, or through the use of malicious documents in emails, known as phishing. External penetration tests are performed to simulate an attack from an external entity trying to access your internal assets.

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