Evaluating a Penetration Testing Company

Rob Hughes and Keith Sharp


It can be difficult to know what to look for when searching for a strategic partner to assist you with your security and risk management processes. More specifically, understanding what makes a good penetration testing company can be difficult without a pre-existing familiarity of the industry. In this blog we are going to discuss the key factors that can help identify a good penetration testing company.

A company or organisation can have many reasons for conducting a penetration test, including,

  • Gaining a better understanding of the effectiveness of their security defences
  • Ascertain risk levels of business critical systems and their related processes
  • To meet strict compliance requirements.

There can be many reasons as to why an organisation looks to utilise a penetration test, however, enabling better security awareness and assurance through remediating security weaknesses, are key goals all organisations should be aspiring too.

Unfortunately, as with any industry, there are good and there are not so good security testing organisations out there selling services. Therefore, InteliSecure have put together an overview on the main areas that should be considered when selecting a security testing company as a strategic partner.

The following three commonly raised questions, will be our starting point for this discussion:

  • How do you find a good Penetration testing Company?
  • What should you consider before engaging a Penetration testing Company?
  • How can you ensure that a Penetration Testing provider can perform the engagement to your requirements and meet your business needs?

Therefore, in order for an organisation to be able to answer these questions, InteliSecure have put together a high level overview of what to look out for and how to engage with the many organisations that are providing penetration testing services:

  1. Understanding what type of testing you require
  2. Ensuring the skill set of the third party consultants can meet your requirements
  3. Understanding the company’s processes and procedures, for example are these documented and aligned to any standard (ISO 27001 etc). 

Let’s look a bit more closely into a few of these specific areas.

Understand the type of testing you require.

Penetration testing, in its true form, can be performed across many different technologies and is usually performed across either an external or internal network infrastructure, which can include physical or virtual servers, workstations, firewalls, network switches, routers and many IP based devices and applications.

Once the scope of the assessment has been defined, you will have to indicate how you want the assessment to be performed. A penetration test in its most basic description is the simulation of an attacker attempting to ascertain and then exploit weaknesses of networked computer systems. The classic categories of the attacker perspective that can be applied to a pen test are known as black box, grey box and white box, these are defined in their basic terms below:

Black box tests are performed without any knowledge of the tested environment. The objective of a black box assessment is to assess the level of security as seen by a third party connected to the internal network or the internet, without any prior knowledge of the environment.

Grey box tests are performed with standard access or with only limited knowledge of the tested environment. The objective of a grey box assessment is to assess the level of security as seen by a legitimate user of the customer who has an account, along with general information about the tested environment.

White box tests are performed with knowledge of the internal structure/ design/ implementation of the tested environment.

Penetration testing is an offensive methodology aimed at replicating a typical attacker, which could be scoped to focus on multiple areas of an organisation, including web applications. Generally, the methodology is better applied through a black box testing perspective, which is unauthenticated and with limited knowledge of the system. The concept is enumerate the information or attempt to bypass / brute force authentication in order to gain an initial foothold.

Typically, a penetration test is completed under a set methodology and resembles the basic principles of the open source security testing methodology manual (OSSTMM) and is scoped to include the subnet ranges, devices or IP addresses, and/or URL’s that are to be included in the assessment.

A myriad of factors can come into play on deciding which attacker perspective to assume for a penetration test and these ultimately depend on the complexity, criticality and management of the systems that are going to be targeted for attack. For example, an organisation may outsource web application development and have limited access or perspective with respect to the detailed hosting information or prior penetration testing assurance of the third party, and so a black box test may be the natural or only choice to assess the solution.

Attacker perspective becomes very important with regards to certain types of penetration testing, such as red team penetration testing exercises. Red team penetration tests, by their nature, are almost always performed on live systems and can include social engineering tactics against company employees and have less restrictions than other types of security assessment. The flow of red team penetration tests is typically goal based, in that a penetration testing team have been given challenges to, for example, gain access to a specific system, or retrieve a password for a specific type of user within the network environment, from a specific starting point (and level of knowledge about the environment that may map to i) a standard employee, ii) an employee in the IT department etc). Red team exercises must be pre-planned in agreement with IT security managers to avoid risk and preserve the integrity of the assessment (i.e. only select employees knowing that attacks are taking place) so genuine defensive responses can be gauged in their effectiveness during the assessment (reviewing intrusion/security monitoring alerts) and thereafter (log analysis etc). Therefore, to facilitate successful red team exercises, both black box and white box perspectives may have to exist in parallel to achieve the goals of the testing safely.

Ultimately a good penetration testing company will always guide a client to the right choices for the environments that are to be tested and should consider the requirements and constraints of the targeted systems when aligning the best choice of attacker perspectives with the target(s) involved. Defense in depth can often be more efficiently scoped and scrutinised by a penetration testing company depending on what background information they have from the outset. Attack perspectives can change depending on the information available, so the above categories are not necessarily rigid and all good penetration testing companies will recognise and highlight any relevant issues when such perspectives are not clear or have to change to best facilitate the proposed penetration testing.

The main objective of penetration testing is to essentially ascertain to what extent the issues and vulnerabilities discovered within a specific environment can be exploited by an attacker and what systems can be breached and how (i.e. can certain vulnerabilities be combined and therefore pose additional or greater risks)

Penetration testing of specific types of network technology can have their own overarching standards and methodologies, a prime example being network applications. Focused application testing differs slightly from a true form penetration test, as this is usually completed using multiple sets of credentials covering multiple roles (i.e. different levels of trust/access are assigned to the attacker perspective to align with the potential threats the application could pose). The principles in focused application testing are usually aligned to the Open Web Application Security Project (OWASP) and can cover web applications, mobile applications and thick client or Desktop applications.  This type of testing aligns with “grey box as a minimum set of information is required to successfully cover the test cases the application naturally presents.

Most penetration testing companies also offer a compliance and auditing type of assessment, which can include authenticated build reviews or servers, workstations, firewall’s and other network security devices, mobile devices etc etc. This type of testing isn’t essentially penetration testing per say, but can be used alongside the typical testing in order to gain a more thorough and comprehensive overview of risk within the environment. When these types of services are combined in this way, the term “Health Check” is usually used to describe the process.

Therefore, it is essentially that you fully understand the type of testing that you require as some compliance requirements, such as the PCI and the Cyber Essentials scheme in the UK, require a combined “Health Check” approach.

The penetration company will usually ask whether the penetration testing is required to meet specific compliance requirements, either through an initial meeting or via a scoping questionnaire, therefore it is essential that you understand the type of testing you require before engaging with the third party. This will allow you to gauge if the company can provide the type of testing you require and the skill set required within its organisation, which leads us onto the next area.

Ensure the skill sets of the penetration test consultants can meet your requirements.

In addition to evaluating the penetration testing company as a whole, you should also take a close look at the actual consultants who will perform the engagement. A good penetration testing company will be able to instantly provide details of their consultant’s professional backgrounds, along with any relevant qualifications or professional certification they may hold individually. Penetration testing, as a specialism, has now become better known in the IT security industry, with many organisations offering different types of certification to assess an individual’s competence in the subject. Certifications offer a way to ensure a baseline level of technical competence and knowledge and understanding of the profession. However, a consultant who can study a subject and pass an exam, may not have the expertise or experience to competently complete the penetration test to your unique requirements. Limitations of experience can exist within a pen testing company and so it should be expected that availability of individuals with niche skills may not always exist across the board. However good penetration testing companies will conduct training or in-house research to push the skill sets of their consultant’s forward to align with advances in technologies and/or tools or to allow their consultant’s to be able to upskill their repertoires.

Within a quote or proposal for penetration testing services from the third-party (which would be derived following the scoping phase), a good penetration testing company would include information on the consultant’s likely to be involved in the assessment.

The following areas should be investigated about each consultant, usually a search on LinkedIn or Google would return valuable results.


Most penetration testing Consultant’s would have graduated from University with some form of Computer security or science degree, however, this may not always be the case. Also, there are many Industry certifications that can be much more focused in penetration testing than a generic degree.

Some of today’s most commonly-recognized certifications include Certified Ethical Hacker (CEH), Licensed Penetration Tester (LPT), GIAC Exploit Researcher & Advanced Penetration Tester (GXPN), or Offensive Security Certified Professional (OSCP). In the UK there are Crest Certifications, Tigerscheme and Cyber Scheme which are aligned to the UK National Cyber Security Centre (NCSC) CHECK program, which deals with Government, Police and other potentially sensitive data.

When it comes to continuous education, the SANS Institute is a private company that also offers high quality information security and cybersecurity training including penetration testing courses to hone ethical hacking skills, including web application security assessments, social engineering, red team operations, wireless penetration testing and more.

Most competent penetration testing consultant’s would have at least one focused industry standard certification which would be focused on a specific area of penetration testing, therefore it is important to review the consultant’s detailed resume to confirm.


Experience within the penetration testing industry can be extremely broad, with many consultant’s coming into the industry directly from either University or from another profession. However, it is essential that in a focused penetration testing role, experience in different areas such as network infrastructure, application and compliance auditing has been gained by the consultant throughout their careers.

Most senior level penetration testers in the industry, who are likely to be the ones who initial scope the penetration test and then lead the assignment, have at least five years dedicated experience and are certified to the senior level qualifications.

Specialist consultant’s would also be required to complete testing across more advanced or lesser known types of security assessment such as red teaming or mobile application testing.

It is therefore vital to ensure the penetration testing company has consultant’s with the right skill set available for your assignment, therefore it is advisable to review any resumes or LinkedIn  profiles for the consultant’s being potentially involved in the project, to ensure they have the relevant skills and experience.

Understand the company’s processes and procedures

All good companies document all of their processes and procedures, some of which are usually available to their clients if requested. Typically, a penetration testing company should be able to provide the following information.

  • Methodologies (covering the different type of testing)
  • Client Engagement Process
  • Data Handling and Retention Policies
  • Complaints and Escalation Procedure
  • Standard Operating Procedures (Covering Penetration Testing Execution)
  • Quality Assurance Policies
  • Information Security Policies
  • Liability Insurance Certificates

This level of documentation should be mature, with policies and procedures being adhered to within the organisation, therefore, it would be wise to work with companies that do have their internal policies and procedure regularly audited.

Also, if an organisation utilises sub-contractors or works with contractors when fulfilling a penetration test, then the procedures for ensuring standardisation across contractors should also be documented. If a client handles sensitive information, the data handing and retention policies may have to align to certain requirements for such data.

Fortunately, most of the established companies working within the industry are dedicated to providing quality assurance for their services. Some companies go a step further and are measured in providing penetration testing services to a set standard, through being aligned to organisations such as CREST (The Council of Registered Ethical Security Testers) in the UK and globally, which has effective and comprehensive testing standards and methodologies in place. This standard could be considered similar to an organisation that has adopted the ISO27001 standard, but is more closely focused on the type of security services a company can offer, be it Penetration testing, incident response etc.

In order to achieved company status to the CREST standard, all policies, methodologies and processes are individually evaluated and have to confirm to a rigorous standard. These companies must also employ consultants who are security cleared to at least UK SC level and have been assessed and accredited to the highest standards of security testing. They can be trusted in order to ethically replicate the threat actors and provide pragmatic advice and direction on how to protect yourself against the constantly evolving threat landscape.

When selecting a partner to provide penetration testing services, researching the company is a vital step in ensuring they are competent and experienced to provide you with the information security assurance you are hoping to achieve. Contact us to get a custom testing approach for your company.