What You Should Know About External Penetration Testing

A penetration test, also commonly known as pentest, is a security assessment that simulates the malicious activity of real-world attackers to identify vulnerabilities in your business systems or applications.

The purpose of pen testing is to understand what vulnerabilities are in your business systems, how they can be exploited, and what the business implications will be if an attacker is successful.

One of the first types of penetration testing that organizations usually perform is external pen-testing. External penetration testing, commonly referred to as external network penetration testing, is a security audit of a company’s peripheral systems.

Your environment includes all systems directly accessible from the internet. By their nature, all systems directly accessible from the internet are the most open because they are exposed and are therefore most easily and regularly attacked.

See Also: What You Need to Know About Internal Penetration Tests

An external pentest aims to locate ways to compromise your externally accessible systems and services, obtain access to sensitive data, and uncover ways for an attacker to attack your customers or users.

In a good external pentest, the security professional conducting the evaluation will imitate the actions of genuine hackers, including running exploits to gain control of systems. They will also test the extent of vulnerabilities discovered to see how far a malicious attacker can break into your network and the business impact of a successful attack.

See Also: PCI DSS Penetration Test Requirements

External penetration testing is usually tested from an attacker’s perspective with no prior access to your systems or networks. External penetration testing is different from another common type of testing, internal penetration testing.

Internal penetration testing tests the scenario where an attacker already has a foothold on a compromised machine or is physically in the building. Although it usually makes sense to cover the basics first and consider internal testing only after regular vulnerability scanning and external penetration testing have been performed.

What is External Penetration Testing?

External Penetration Testing is a combination of manual and automated testing of a client’s public systems using the internet to simulate a hostile attacker. Public systems include websites and e-mail servers with public IP addresses that users on the internet can access.

External infrastructure penetration testing methodologies to look for various security flaws include the following steps:

  • Identifying firewall misconfigurations,
  • Identification and exploitation of vulnerabilities,
  • Finding and testing administrative services and interfaces,
  • Other attack techniques.

External penetration testing will identify potential attack vectors where a system can be compromised remotely. The result of the external penetration test should be presented with a detailed penetration test report with steps to reproduce the findings and recommendations for improvement.

External Infrastructure Pen Testing is recommended annually or after significant network changes to internet-facing systems and services.

Why Do You Need External Penetration Testing?

You should perform External Penetration Testing to ensure that no threat actors can enter your environment through your external network. External Penetration testing is the fundamental first step in your cybersecurity journey because your systems that can be accessed from the internet form the first step of your security.

See Also: External Penetration Testing Checklist

Relying on next-generation firewalls and trusted cloud security providers to host and secure a company’s infrastructure might lead to a false sense of security. Vulnerabilities are not necessarily a product or service issue but include human error related to misconfiguration.

Many companies are subject to compliance and regulatory obligations, such as PCI DSS, and are required to conduct independent penetration testing annually. The aim is to identify security vulnerabilities before attackers that could result in the unauthorized disclosure, misuse, alteration, or destruction of sensitive and confidential information.

We can list the benefits of External Penetration Testing as follows:

  • You provide visibility into how a remote attacker could compromise your public systems.
  • You have insight on how to prioritize your security spending based on actual risks.
  • Understanding how an attack could occur provides an opportunity to formulate an incident response plan based on your potential risks.
  • Improved security capabilities of your IT team with suggested improvement paths.
  • Your business’s compliance and regulatory requirements are met.

How to Perform an External Penetration Test?

Scheduling an external pentest is usually as simple as contacting the cybersecurity consultancy of your choice and forwarding them a list of domains and IP addresses/ranges where your perimeter systems and penetration test scope are determined.

External pen testing is usually conducted on a “Black Box” basis. Black box penetration testing means that no privileged information is provided to testers, such as application credentials, infrastructure schematics, or source code. In this way, black-box penetration testing is similar to where a real hacker targeting your organization would start after discovering a list of your IPs and domains.

There are a few key points and steps to consider when planning your external penetration testing:

  • Get information about the penetration testing specialist or company that performed your test. A qualified penetration testing specialist or firm?
  • Bids are generally based on man/day rate, and the scope of your work is determined by the number of days required to complete the assessment. These can vary between pentesting companies, so you need to compare what’s on offer and what’s on offer.
  • Check what is included in the external penetration test. Reputable consultants provide a proposal or statement of work outlining the work to be undertaken. Pay attention to what is inside the penetration test and what is outside the scope of the penetration test.
  • The external penetration tester or firm should also provide controls for your exposed services, including compromised credentials reuse, password spraying attacks, and web application testing on publicly accessible applications.
  • Social engineering tests can also provide added value and are ideal for measuring your employees’ general information security awareness.

What are the Differences Between External Penetration Testing and Vulnerability Scanning?

A thorough external vulnerability scan is usually included in an external penetration test. A pentester will manually explore all output from the scan tools to eliminate false positives, run exploits to verify the extent and impact of the vulnerability, and link multiple vulnerabilities to produce more effective exploits.

A vulnerability scanner reports that a service has a critical weakness, a penetration test attempts to exploit that weakness and control the server. If successful, the pentester will use newly acquired access to go further and compromise more systems and services.

See Also: What are the Requirements for PCI DSS Vulnerability Scanning?

Vulnerability scanners usually detect potential issues, while a penetration tester thoroughly investigates them and reports whether the vulnerability needs attention. Vulnerability scanners, for example, regularly report on ‘Directory Listing,’ which occurs when web servers display a list of all files and directories on the server.

A directory listing vulnerability is not necessarily a vulnerability per se, but it should be investigated. Suppose a sensitive file, such as a backup configuration file containing credentials, is exposed and listed by directory listing.

In that case, a simple information disclosure issue can quickly become a high impact risk for your organization. The penetration tester’s job includes carefully reviewing a set of outputs from vulnerability scans to ensure any identified vulnerabilities are identified.

There are also some additional activities and security tests that an attacker would perform that are not served by vulnerability scanners. If you want these to be covered, check the offer or ask questions of the relevant firm or specialist before scheduling the pentest:

  • Will there be brute-force or continuous password guessing attacks to attempt to compromise user accounts on exposed VPNs and other services?
  • Scraping darknet and breach databases for known breached credentials of your employees and testing them in admin panels and services?
  • Will there be web application tests with a self-registration mechanism available?
  • Will your employees be subjected to social engineering attacks such as phishing?

Finally, keep in mind that new significant vulnerabilities are discovered every day, and the most severe flaws are often exploited within a week of their discovery.

While an external penetration test is an essential consideration for delving into the security of your exposed systems, it’s best to use it to complement the regular vulnerability scanning that should be in place.

Regular scanning for security issues helps organizations complete manual testing as it provides a good level of continued security coverage between manual testing.

Many companies today still use annual penetration testing as their only line of defense. Still, understanding how often vulnerabilities emerge, automated vulnerability scanning solutions identify the first point of vulnerability for any company, and manual penetration testing is a powerful security boost.

What are the External Penetration Testing Methodology and Stages?

The external penetration test can be divided down into seven different parts to guarantee that it operates smoothly:

Stage 1: Contract Agreement

As with any significant project, selecting a competent and reliable service provider is the first step in ensuring that external penetration testing runs smoothly and achieves the intended results. It’s best to look for IT security and security firms that have successfully conducted external penetration testing for other businesses in your field.

Experienced penetration testing firms will provide vague assurance that your company understands its specific IT security requirements and can provide you with a comprehensive understanding of the security risks and threats you need to consider and prepare for.

After determining the appropriate security agency you wish to engage with, you must now define and agree on the participation guidelines for external penetration testing. In addition to the test methodologies to be used in external security testing, it is equally important to determine the depth of discovery to be performed.

Also, external penetration testing will undoubtedly give an ethical penetration tester insight into access to and databases of information that can be pretty sensitive. Therefore, the organization or person performing the external penetration test should sign a comprehensive non-disclosure agreement before performing the test to protect the integrity of your company’s information assets.

While penetration testing firms typically have standard agreements and Confidentiality Agreements for external penetration testing and services, other items you might consider stipulating in the service agreement are as follows:

  • How will the company or person performing the penetration test coordinate and work with your IT team?
  • When will penetration tests be evaluated, and will the tests affect your company’s operational efficiency?
  • How will the company or person performing the penetration test transmit, store and delete the obtained company data?

Stage 2: Planning and Discovery

A successful external penetration test’s planning and discovery phase should prioritize and focus on comprehensive information gathering. A thorough understanding of the objective will allow your organization to build a solid foundation to support the other vital phases of external penetration testing.

The first phase will focus on acquiring open-source intelligence, including an examination of publicly available data and sources. The goal of the discovery phase is to find sensitive information, such as e-mail addresses, usernames, software information, user instructions, and forum postings that can be useful in later testing. A kick-off notification should be provided to the client when testing officially begins.

Also, this step will involve searching for sensitive information. Internal communications should not be publicly available, such as salary information or other potentially harmful information.

The information generally sought during the discovery phase is as follows:

  • Subdomains
  • Login portals such as Citrix, OWA, VPN, SharePoint
  • Technology types such as IIS, Apache
  • E-mail addresses
  • Usernames

An ethical penetration tester should gather as much information about the target by conducting deep research on various online platforms or conducting open-source intelligence drills. The discovery step will provide you a better grasp of the company, its processes, and the types of clients with which it does business.

Also, the exercise of discovery and information gathering can help organizations understand the amount of information available about them in the public domain and guide them on how to secure it going forward.

Additionally, during the planning and discovery phase, a comprehensive inventory of the target’s information assets is required to identify all potential features and services in the organization’s network that could be attractive or attractive to cybercriminals.

Once you have the post-discovery collected information at hand, you should contact the external penetration testing agency of your choice to determine the external penetration testing objectives and scope of testing.

The initial meeting will help both teams agree on key performance indicators that can measure the success of pen testing and define the testing constraints necessary to ensure information security and safety.

Tools used during the discovery phase of external penetration testing may include Recon-ng, Maltego, Shodan, Fierce, SimplyEmail, TheHarvester, SpiderFoot, Email Hunter, FOCA, Pastebin, Google Hacking, Wayback Machine, custom scripts.

Stage 3: Target Scanning and Vulnerability Detection

This phase of the external penetration test is where the expert performing the penetration test performs a vulnerability assessment. In addition, during the vulnerability detection stage, it is the stage where the vulnerabilities that attackers can use in the target network to gain access in some way are detected, and the potential security risks are measured if no precautions are taken.

The external penetration tester will send various requests to the target network to collect preliminary data and record how the system will respond to multiple inputs from a targeted cyberattack.

The results of the target scanning and vulnerability detection phase may include:

  • Recognize the structure of a directory on a specific server.
  • Detecting shared or open drives on a particular network
  • Provide authentication access to FTP or web servers
  • Identifying available SMTP access points via error messages
  • Identify code signing certificates that can be used to sign and forward malicious scripts

The vulnerability analysis phase will cover the discovery and enumeration of all in-scope targets and applications. For each discovered service, automated and manual techniques are used to find vulnerabilities with in-scope targets.

The penetration tester will try to determine the version of the service and will look for previously released vulnerabilities. The penetration tester will also test the unauthenticated targets and applications discovered for vulnerabilities listed in the OWASP Top 10.

Finally, each service will be manually reviewed and tested for default credentials or other vulnerabilities that might be missed in an automated scan.

Tools for target scanning and vulnerability identification may include Nessus, Nmap, Burp Suite Pro, Metasploit Framework, Netcat, dirb, SSLscan.

Stage 4: Gaining Access

The gaining access phase of the external penetration testing process is where the data collection phase will be thoroughly tested but can also be used to gather data deeper within the target network.

While vulnerabilities are identified within a network, it does not necessarily mean that they can be exploited. Therefore, it is essential to prioritize these weaknesses according to their importance and their level of impact on the organization’s operations.

Once the system’s critical vulnerabilities have been duly identified, it is time for the external penetration tester to exploit these vulnerabilities to gain access and control over the target, which could be a firewall, a secure network, or a specific system.

The external penetration tester should use the list of identified security vulnerabilities to determine exploitable vulnerabilities and gain access to the target.

A malfunctioning or unsafe device, host or network configuration, encryption and authentication issues, compromised code or command injection, and loopholes in user session management are all common vulnerabilities.

The gaining access phase helps assess the realistic level of risk associated with successful exploitation, analyze the probability of exploit and attack chains, and consider any mitigating controls that may be in place.

Tools that can be used in gaining access may include Metasploit Framework, Hydra, Burp Suite Pro, Sqlmap, ExploitDB.

Stage 5: Protecting Access

The access protection phase is when an attacker manages to break into your environment undetected, then takes an inventory of everything inside, claims all your valuable information detected and remains undetected so that it can return at a different time.

Once the external penetration tester has successfully accessed your system, they will try various methods to ensure permanent and permanent access despite all the changes implemented.

This is a crucial step because remaining undetected, even by key system security measures in place, will allow the external penetration tester to be on your network, become familiar with its intricacies and intricacies, and examine what cybercriminals can do.

The external penetration tester must provide specific details, such as how long it takes them to access your systems and how your organization can effectively fix these errors.

After successful access, the analysis will continue, including infrastructure analysis, rotation, sensitive data identification, data theft, and identification of high-value targets and data.

Tools to protect access may include Metasploit Framework, Burp Suite Pro, custom scripts.

Stage 6: Exploitation

Once hackers get access to your networks, they will strive to get as close to the places where your company’s most valuable information is stored as possible before being recognized and captured by current security measures.

However, the primary goal of the external penetration tester will be to identify all possible paths to access confidential data that take the least amount of time to execute. Pentester should also be able to tell you which vulnerabilities they used to obtain access to your systems, as well as the tactics and techniques they employed to do so.

There are different types of penetration tests, network, wireless, and physical, which can be used separately or combined. Each attack can therefore be different and customized, as it must take into account existing scenarios in the network for it to be entirely successful.

The exploitation stage is also the stage where the provisions of your service contract will apply. The external penetration tester should not be able to go beyond the agreed project scope to ensure the integrity of your company’s data remains intact while continuing to diagnose potential and current security threats.

Tools used during the exploitation phase may include Metasploit Framework, Burp Suite Pro, custom scripts.

Stage 7: Reporting

After the penetration test is complete, which can take a week or two depending on the scope and complexity of the external penetration test, the firm performing the external penetration test should submit a comprehensive report outlining the penetration test results with recommendations for improvement.

The penetration test report should begin with an executive summary that clearly explains the purpose of the test, the tactics and techniques employed to gain access to the system, and the corresponding risk levels.

This collected data and evidence can encourage the company’s management team to take decisive action. They now better understand how these risks may affect their organization’s reputation and operations and what resources will be required to rectify the situation.

The second part of the report will provide specific technical valuable information to the organization’s IT security team to efficiently resolve any security issues discovered during penetration testing.

This section of the penetration test report should also show how the external penetration testing company restored and cleaned its network and returned it to its state before the external penetration test began.

Identifying vulnerabilities in your company’s IT framework is the first and most crucial step in protecting it from data breaches and cyberattacks. Your company can take immediate action against these vulnerabilities and prepare your networks for possible future cyberattacks by performing external penetration tests.

Surkay Baykarahttps://www.pcidssguide.com
A passionate Senior Information Security Consultant working at Cyberwise. Over the past 15+ years my professional career has included several positions beginning as a developer and IT administrator, working my way up to a senior Technical Performance Consultant before joining Biznet back in 2015. I had several different roles at Cyberwise, including Penetration Tester and PCI DSS QSA. In my job as a QSA, I found my passion and worked closely with the Audit and Compliance team. I've been working inside InfoSec for over 15 years, coming from a highly technical background. I have earned several certifications during my professional career including; CEH, CISA, CISSP, and PCI QSA.

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