71% of organizations consider cybersecurity at the top of their priority lists. Ironically, more than 20% of these organizations don’t test their software, landscapes for security vulnerabilities and loopholes. But this is just the tip of the iceberg. Here’s an alarming excerpt from a study conducted by Frost and Sullivan:

“A large-sized organization in the Asia Pacific can possibly incur an economic loss of US$30 million, more than 300 times higher than the average economic loss for a mid-sized organization (US$96,000) [in the case of a breach]; and cybersecurity attacks have resulted in job losses across different functions in almost seven in ten (67%) organizations that have experienced an incident over the last 12 months”.

These facts and figures are deeply concerning. However, what can an organization do to prevent bearing the cost and impact of cyberattacks?

Adopt periodic penetration testing.

In cybersecurity parlance, penetration testing refers to a series of security tests that detect, respond and remediate threats before they can gain entry into your mission critical infrastructure. But how does penetration testing work? This blog just answers that. Deep dive into the 3 types of penetration tests to know how each of them contributes to making your organization cyber-safe and threat resistant.

Meet the Holy Triad of Penetration Testing: Black Box, White Box & Gray Box

Black Box Penetration

In black box penetration testing, the ethical hacker has no knowledge about the security system. They have no access to codes, blueprints, networks and applications used by the business. The only thing they have access to are user privileges.

The tester goes in uninformed and detects vulnerabilities using manual and automated penetration techniques including vulnerability scans, trial-by-error methods and social engineering attacks. This is why black-box penetration testing is called closed-box penetration testing.

In the world of cyber-attack testing, black-box penetration is considered accurate, because just like the cybercriminal, the tester needs to enable surveillance and information gathering to gain insights into the security systems of the organization.

Why Should We Perform Black-box Penetration Testing?

Considered to be accurate and unbiased, the tester adopts a neutral approach towards detecting security defaults and vulnerabilities. Had the tester carried any pre-conceived knowledge about the security system, he would have only been focused on identifying a specific set of security issues and missed out on the rest. Other than this aspect, black-box penetration testing helps in:

  • Replicating a real cyberattack to discover security anomalies.
  • Detecting exposed vulnerabilitiesexposed vulnerabilities and configuration issues by assessing applications on run time.
  • Identifying inaccurate product builds like missing modules or files.
  • Searching for errors like errors in information disclosure, input and output validation errors.
  • Resolving issues quickly with detailed remediation techniques
  • Mapping out common vulnerabilities like SQL injection, XSS and CSRF
  • Finding security flaws in interactions with security environments like inaccurate configuration files and unhardened applications.
  • Looking out for server misconfiguration issues.

Stages of Blackbox Penetration

There are five stages involved in operating a black-box cybersecurity test. Let’s explore each one of them

Stage 1: Reconnaissance
This step involves gathering preliminary information about the security system. The preliminary information includes email addresses, employee information and IP addresses.

Stage 2: Scanning & Enumeration 
Taking reconnaissance one step further, here, the ethical hacker gathers additional insights about the targeted network including operating systems, user accounts, connected systems and software types.

Stage 3: Vulnerability Discovery 
The tester deploys a series of tests to gather insights into the vulnerabilities of each system or network. For instance, conducting CVEs in third-party applications utilized by the targeted system.

Stage 4: Exploitation 
Ethical hackers will devise threats and malicious actors to exploit further system vulnerabilities. They do this by gaining access to the core part of the systems within the shortest time possible.

Stage 5: Privilege Escalation: 
After accessing the main parts of systems, they gain complete control over the entire system or application.

Techniques for Black Box Penetration




Considered to identify known and unknown vulnerabilities, fuzzing takes place by inserting random data into the targeted system and checking how the system responds to it. If the response digresses from normal behavior, it may highlight a potential vulnerability.

Syntax Testing

This kind of testing involves deploying specialized tools and knowledge to check for flaws in source codes, function calls, and loop structures. Detecting coding flaws or logic errors can prevent the occurrence of system breaches.

Exploratory Testing

Useful for identifying hidden threats that may have been overlooked by traditional testing methods, this kind of testing conducts port scans, service identification scans and vulnerability scans to unravel flaws in the organization’s security posture.

Test Scaffolding

Offers a proper framework to test and validate the effectiveness and efficiency of each security measure and control

Behavioral Analysis

Involves real-time monitoring of unusual behaviors within the applications or systems and offers insights to secure security networks.

Challenges in Black-box Penetration Testing

The black-box penetration tests may fail to offer a detailed analysis of your source code and internal systems. Since these tests rely mostly on trial-and-error and guesswork, it may take months for reconnaissance until the tester finds a vulnerability. However, this depends entirely on the tester’s experience and other criteria.

White Box Penetration Testing

White box penetration testing enables hackers to have complete knowledge of the targeted system or application. This includes having information about the system, target, networks, login credentials, source code and access to administrative privileges.

Known as crystal penetration tests, they are usually conducted at the beginning stages of product development. This helps the tester detect any security loopholes or vulnerabilities before it is sent to the developer. You can even carry out these crystal tests during product integration, product release and cyberattack outbreaks. Apart from potential security threats, white box penetration testing helps to identify bad coding practices and supply chain issues.

Why Should We Perform White Box Penetration Testing?

One of the main advantages of carrying out a white box cybersecurity test is that you can resolve vulnerabilities immediately before the application goes out live in the market. Along with this, white box penetration testing helps in:

  • Writing test cases quickly as the tester has a thorough understanding of the security system.
  • Analyzing software code structures found in design documents, programming language specifications, source code, UML diagrams, programmer’s comments, object model, or the high-level language model.
  • Identifying vulnerabilities at an early stage of SDLC.

Stages of White Box Penetration Testing

The 5 stages of white penetration testing include:

  • Gathering Information: The tester accumulates in-depth information about the targeted system including insights into operating systems, hardware and software applications and network architectures. This is done to enable attack scenarios.
  • Analyzing Vulnerabilities: This step includes detecting vulnerabilities in the systems including firewall configuration, poor password policies and expired software.
  • Developing Attack Scenarios: After the vulnerabilities have been identified, the tester builds attack scenarios to depict how systems can be harmed during an actual event of cyber attack.
  • Realization of Attacks: Attack scenarios are enabled by targeting the vulnerable parts of the system. Both security loopholes and defense measures are studied thoroughly.
  • Results and Reporting: After gathering data from the attack scenarios and covering vulnerabilities, this comprehensive report uncovers the concern areas of the targeted network and suggests strong remediation measures.

Techniques for White-box Penetration Testing



Statement Coverage

In coding parlance, it means that every line of the code is implemented till the end of the testing.

Branch Coverage

Testing the outcomes and results of your code

Path Coverage

Testing every path of the code from beginning to end

Condition Coverage

Assessing the results of the logical conditions in the code.

Challenges in White-box Penetration Testing

White-box penetration testing is considered to be expensive and may fail to scale with bigger applications. In most cases, it is time-consuming as exhaustive testing is implemented to test large applications. The tests are more susceptible to errors as the tester may overlook some coding mistakes during the regular process of analyzing the line or path of the code.

Gray-box Penetration Testing

Gray-box penetration testing serves as an intermediary between black box testing and white box testing. While black box testing focuses on a system’s external inputs/ outputs and white box testing on the system’s internal code, gray box testing is concerned with testing the system’s internal infrastructure to detect any potential security flaws.

Why Should We Perform Gray Box Penetration Testing

Gray box testing is effective for very large and complex systems where a tiny error can wreak havoc on the system. The best part is that testers don’t necessarily need to have extensive coding knowledge or programming skills. Considered essential to the quality assurance process, this penetration testing comes with the following benefits such as:

  • Enabling both black box and white box testing techniques.
  • Creating effective test scenarios as the tester has a comprehensive knowledge of the internal systems.
  • Identifying vulnerabilities that may have been overlooked during unit testing.
  • Resolving issues immediately by changing the partially available code

Stages of Gray Box Penetration Testing

The 10-step gray box penetration testing involves:

Stage 1: Choose Input
Select black box and white box testing inputs

Stage 2: Assess Output
Identify the outputs based on the selected inputs in stage 1.

Stage 3: Select the Key Paths
Choose the major paths for the testing phase.

Stage 4: Choose Subfunctions
Execute subfunctions to test in-depth about the product.

Stage 5: Select Subfunction Input
Choose inputs for subfunctions.

Stage 6: Identify Subfunction Output
Select outputs for the subfunctions based on the inputs of stage 5.

Stage 7: Perform Subfunction
Apply test case for the subfunction

Stage 8: Verify executed subfunction
Verify to check if the test results are accurate or not

Stage 9: Repeat Step 4 and Step 8
Stage 4 and Stage 8 should be repeated for the other subfunctions

Stage 10: Repeat Step 7 and Step 8
Execution and Verification should be applied to other subfunctions

Techniques for Gray Box Penetration Testing




The targeted system is broken into many variables and each variable is tested for vulnerabilities.

Orthogonal Array Testing

Discovers a wide variety of potential software defects.


Uncovers system vulnerabilities and offers a holistic view of the organization’s security posture.

Challenges in Gray Box Testing

One of the main disadvantages of gray box cybersecurity testing is that the tester may not unravel all the hidden security vulnerabilities as they don’t have complete visibility into the system. At the same time, limited access to source codes and application mapping and analysis processes lowers the speed and efficiency of grey box testing.

Keep Security Vulnerabilities Out of Reach with Cloud4C

Nowadays, organizations are following the ‘defense-in-depth’ approach where no single security control attack can shut down your entire IT infrastructure. Penetration testing helps organizations iron-out this approach to ensure that the networks and systems are safeguarded through implementation of a series of protection schemes.

Cloud4C, one of the leading managed security services providers, secures your systems and networks with its 360-degree threat and vulnerability analysis and penetration testing services. Our VAPT solutions offer end-to-end vulnerability analysis and scanning tools to assist organizations in detecting and resolving complex and hidden vulnerabilities. Along with this, our exhaustive array of MDR, SIEM-SOAR, SOC, threat intelligence solutions and services ensure your mission-critical operations run risk-proofed always. Get in touch with us today for a FREE Cybersecurity Assessment.

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Team Cloud4C
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Team Cloud4C

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