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Penetration Testing: A Complete Guide

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You wouldn't buy a car without ensuring its safety features have undergone rigorous testing, would you? Why risk using an application that hasn't undergone similarly meticulous evaluation? 

Car manufacturers assess a car's safety mechanisms and general performance by running it through a gauntlet of tests that help identify and address potential vulnerabilities. Software developers do the same internally and externally with the help of third-party experts. 

In essence, penetration testing (or simply pen testing) is the software development equivalent of hiring a car safety inspector to evaluate the security features of a new vehicle model before it hits the market. 

What Is Penetration Testing?

A penetration test is a process in which software companies hire a third party to hack their application deliberately. These professional “ethical hackers” systematically probe your computer system or network to identify and address security vulnerabilities. 

By doing so, organizations can fix potential issues before they become real threats, just as a car manufacturer addresses safety concerns before putting a new vehicle on the road. This approach ensures the safety of both digital and physical systems.

A penetration test evaluates your systems and applications to find potentially undetected issues—design flaws, configuration errors, bugs, secrets or insecure dependencies in code—that make your app or system more susceptible to cyberattacks.

Instead of waiting for a real hacker to find vulnerabilities and reactively solving them, penetration tests allow a benevolent, professional, expert third party to attempt to break into your system without intending to cause damage if they find a way in. 

Why Is Pen Testing Important?

To ensure your company’s infrastructure remains secure and well-protected, pen tests should be performed regularly—at least once a year. 

With the rate at which applications and computer systems are being hacked—and the rate at which the cost of these types of attacks is growing—organizations are rightfully prioritizing application security (AppSec).  

IBM’s 2023 Cost of a Data Breach report states that the average data breach costs a company is $4.45 million. How high these costs grow depends significantly on how prepared organizations are to deal with cyberattacks and data breaches. 

Identifying and neutralizing attacks and notifying affected parties costs a lot of money. Bad breaches can also lead to operational disruption and damage your company’s reputation. 

Penetration tests help your team decrease the chances of a severe breach occurring. They also prepare you and show you what to do if a break-in occurs. Pen tests are like fire drills—they take a deep look into your organization’s security policies to determine their effectiveness and whether they need to be bolstered. 

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What Are the Benefits of Penetration Testing?

Pen testing is one of the best methods development teams can use to ensure that their application is adequately protected and secure, helping you to identify potential weaknesses in application security, Development teams today recognize the importance of security, with 84% of them claiming that they conduct regular security audits, according to your 2024 State of Software Quality report

Pen tests can dig deeper than your team’s regular vulnerability assessments can. Vulnerability assessments are regular, automated, security scans that search your code and system for common flaws that can lead to security issues. Codacy Security, for example. is a vulnerability assessment tool that scans your code, checking it against over 2,000 static analysis security rules across 20 languages.

Penetration testing takes these practices a step further. In pen testing, testers scan applications and systems to detect vulnerabilities and attempt to exploit vulnerabilities they uncover, impersonating the actions of a malicious hacker. If a pen tester can exploit a vulnerability successfully, so can a bad actor, meaning that pen tests rarely yield false positives.

Security testing gives a more complete picture with pen tests since they use both automated tools and manual processes. This method of testing gives your team a more in-depth understanding of your vulnerabilities and the potential damage these defects can lead to, helping your team with the following processes: 

Attack Preparation 

Prevention is important in application security, as is knowing what to do when a breach occurs. Penetration tests help your organization create a plan of action to handle any malicious attack effectively. 

They also serve to help you evaluate the effectiveness of your response plan. How quickly can your team neatly mitigate the threat? How effectively can you expel bad actors infiltrating your app or system? 

Risk Identification

Pen tests provide deep insights into where your application is most vulnerable. Recognizing your weaknesses helps you assemble the proper security tool stack and develop your security protocols based on your company’s risk profile. 

Risk identification through pen testing helps educate your developers as well. When your engineers understand how hackers launch their attacks, they can work to improve their knowledge and execution in those particular vulnerable areas of AppSec. 

Regulatory Compliance 

Penetration tests can ensure that your team's work in regulatory compliance performs as envisioned. Some of the most common data security regulations, including the Health Insurance Portability and Accountability Act (HIPAA) and the General Data Protection Regulation (GDPR), focus primarily on security controls. 

Some standard regulations, like the Payment Card Industry Data Security Standard (PCI-DSS), require regular pen testing. 

Types of Pen Testing

The diversity of penetration testing types stems from the multifaceted nature of cybersecurity threats and the unique vulnerabilities associated with various aspects of an organization's infrastructure. 

Cyber threats are dynamic, and security postures need to be adaptive. Various pen testing types ensure a more comprehensive assessment of an organization's security defenses.

Application Pen Testing

Application pen tests meticulously scrutinize vulnerabilities within applications and their associated systems. This includes a wide spectrum of digital domains such as web applications, mobile and Internet of Things ( IoT) apps, cloud applications, and application programming interfaces (APIs).

The initial steps of application pen testing often involve referencing the Open Web Application Security Project (OWASP) Top 10, a compendium of the most critical vulnerabilities in web applications. This guide offers a foundation for testers, addressing concerns like malicious code injections, misconfigurations, and authentication failures.

While OWASP checks are a good starting point, complete application pen testing delves deeper to seek out less common security flaws and vulnerabilities that may be unique to the specific application under examination.

Application penetration testing commonly accesses your software for the following: 

  • Structured query language injection (SQLi): Looking for vulnerabilities where malicious SQL queries could be injected into user inputs, potentially leading to unauthorized access to sensitive data.

  • Cross-Site Scripting (XSS): Identifying vulnerabilities that could allow hackers to inject scripts into web pages, compromising their sessions.

  • Authentication bypass: Simulating attempts to bypass authentication mechanisms, such as weak password policies or multi-factor authentication flaws, to evaluate access controls' robustness.

  • Session hijacking: Exploring vulnerabilities that could allow unauthorized access to a user's session, potentially leading to identity theft or unauthorized transactions.

  • File inclusion vulnerabilities: Identifying vulnerabilities that could allow malicious users to upload and execute arbitrary files on the server, compromising system integrity.

Network Pen Testing

Network pen testing broadens its scope to encompass a company's entire computer network. In network pen testing, both external and internal tests are performed to identify the following types of threats: 

  • Unauthorized access attempts: Looking for vulnerabilities that could allow unauthorized access to the network by simulating external hackers. This includes exploiting weaknesses in firewalls, routers, and servers facing the internet.

  • Phishing attacks: Launching phishing campaigns to assess employees' vulnerability to email-based attacks by emulating real-world scenarios. This helps identify potential points of compromise through social engineering.

  • Denial of service (DoS) attacks: Attempting to overload servers with traffic to identify weaknesses in handling and mitigating denial-of-service attacks to assess the network's resilience. 

  • Network sniffing: Employing techniques like packet sniffing to uncover sensitive information transmitted across the network. 

  • Insider threat simulations: Pen testers with internal access (or simulated access) mimic the behavior of a malicious insider, exploring the network to identify vulnerabilities that could be exploited from within.

  • Stolen credentials: Attempting to use stolen or compromised credentials to gain access to sensitive areas of the network to assess the effectiveness of internal access controls and password management.

  • Lateral movement: Assessing how easily an attacker could move laterally from one compromised system to another, potentially gaining access to critical resources.

  • Abuse of privileges: Exploring whether users with legitimate access can abuse their privileges to gain unauthorized access to sensitive data or systems. 

  • Misconfigured security settings: Assessing whether systems are properly configured to prevent unauthorized access and to ensure data integrity. 

Hardware Pen Testing 

Cybercriminals employ many tactics to compromise security on a variety of levels. So, even if your software and network are well-protected, your hardware might be vulnerable if proper precautions haven’t been taken. 

Different types of pen tests require specialized knowledge and skills. Professionals who perform application pen tests need coding and web technologies expertise, while hardware pen testers delve into device-level vulnerabilities.

Hardware pen tests extend their scrutiny to the physical devices connected to the network, including laptops, mobile and IoT devices, and operational technology (OT). Some of the most common hardware threats examined in hardware pen testing include: 

  • Physical access exploitation: Simulating scenarios where an attacker gains physical access to devices connected to the network, potentially extracting sensitive data or planting malicious hardware.

  • Operating system exploits: Explore weaknesses that could be exploited to gain unauthorized control over hardware.

  • Device firmware vulnerabilities: Looking for vulnerabilities in device firmware that could be exploited to compromise the functionality and security of connected devices.

  • Unsecured ports and interfaces, Bluetooth, and wireless protocols: Identifying vulnerabilities related to unsecured ports and interfaces, Bluetooth, and other wireless protocols that could be exploited for unauthorized access or data interception.

Personnel Pen Testing 

Personnel pen tests shine a spotlight on the human element of cybersecurity. These tests aim to uncover vulnerabilities that could be exploited through social engineering attacks by assessing employees' cybersecurity hygiene. 

Phishing, vishing, and smishing are employed to gauge employees' susceptibility. Physical office security assessments that simulate real-world scenarios are also performed, like attempting to gain unauthorized access by exploiting lax building security.

Some other personnel threats that are scrutinized in pen testing include: 

  • Impersonation techniques: Attempts to gain physical access to secure areas by impersonating delivery personnel or exploiting lax building security, a method known as "tailgating."

  • USB drop attacks: Leaving USB drives in common areas to test whether employees insert them into workstations, potentially exposing the network to malware or other threats.

By simulating these threats, organizations can gain insights into potential weaknesses in their applications, hardware devices, and personnel practices, allowing them to address vulnerabilities and enhance overall cybersecurity proactively.

Common Penetration Testing Methods

In explaining the types of penetration tests, we’ve already touched on the fact that internal and external testing methods exist.

The method by which these internal and external tests are performed is often referred to as white-box testing. White-box testing means the penetration tester is given information about the target network before initiating the assessment. This includes IP addresses, network infrastructure schematics, protocols in use, and even source code. In this case, the tester's task becomes more straightforward, as they have a roadmap to guide their efforts. This approach allows for a more informed and deliberate evaluation of the system's security.

In external pen tests, the focus is on evaluating the security of a company's Internet-facing assets to identify vulnerabilities that external threats may exploit. Internal penetration testing simulates attacks by someone with access to an application behind its firewall to assess how well the internal security measures can withstand threats from within the organization.

Another type of white-box testing is targeted testing—a method in which the tester and security personnel work together, sharing information about their movements and actions. This cooperative approach serves as a valuable training exercise, offering security teams real-time feedback from a hacker's perspective.

The concept of black-box testing relies on withholding as much foreknowledge from the testers and those being tested as possible. Blind testing, in which the pen tester knows as little as possible about the target, is a popular black-box testing method. 

Typically, they will only be provided with the name of the targeted enterprise. By limiting the information given to the tester, blind testing aims to emulate the unpredictability and urgency of a genuine cyber threat and give companies a real-time glimpse into how an actual application assault might unfold. 

Double-blind testing takes the element of surprise a step further. The pen tester has no specific instructions on attacking the company, and the company has no advance knowledge of the simulated attack. Mirroring real-world scenarios, the target company is unaware of the impending breach, providing an authentic test of its ability to respond and defend without prior preparation.

Who Performs Pen Tests? 

Penetration tests are performed by third-party security professionals—not someone from within your company. These companies or individuals hired to perform pen tests are AppSec professionals who work in ethical hacking—using various tools and techniques that malicious hackers use to discover and infiltrate vulnerabilities. 

In ethical hacking, tests are simulated to find ways your app or system can be compromised, but ultimately, the pen testers refrain from doing actual damage. Instead, their role is to report their findings so that you can protect yourself from malicious hackers. 

Pen testing is best performed by third parties with no deep knowledge of your app to uncover blindspots that someone who works in your organization, regardless of skill and experience, might overlook simply because they helped build your app and are familiar with how it works. 

The Five Phases of Penetration Testing

The execution of a pen test usually occurs in the form of a five-step plan that enables the tester to understand your potential vulnerabilities and what type of damage bad actors would be able to enact once they’ve exploited these capabilities. 

1. Reconnaissance

This is the research phase of pen testing. Testers will gather information about your application or system, both by getting internal access from you and from doing independent, external research from more public sources. 

As an internal method, your company could give them access to your source code and allow the pen testers to freely analyze it to identify possible ways into your application. Pen testers can also scour the Internet to find public information that could help them infiltrate your system. This could be public documentation you’ve made available, documentation from open-source tools you’ve integrated into your app, news articles about your company, employee social media or GitHub accounts, and more. 

Pen testers might even try to use social engineering tools and methods to extract information from employees or close associates of your company that they can use to uncover vulnerabilities. 

2. Scanning 

With the reconnaissance done, the pen tester now has somewhat of an idea of how they would be able to attack your application. The next step is to closely examine your application to confirm potential vulnerabilities to see how your application would respond to an intrusion attempt. 

In this phase, automation is often used. Static code analysis tools give the pen tester a deeper understanding of your code and potential vulnerabilities. The next step is to understand how the target application will respond to various intrusion attempts.

This phase could also include continuing social engineering schemes for stealing sensitive credentials that could help them infiltrate your application. These methods also help test how well-versed your employees are on social engineering threats and how well they can spot them.

3. Exploitation

In the next phase, the pen tester uses all of the information they have gathered to try and gain access to your application. They often used common AppSec security threats and methods such as SQL injection, brute-force attacks, denial-of-service attacks (DDoS), and cross-site scripting,

4. Escalation

If they manage to gain access to your system, the escalation phase focuses on maintaining access and how much damage they can potentially do. The goal is to stay connected long enough to intercept secrets and other sensitive information, modify your code, and alter your application's functions. 

This phase is all about accessing the potential impact of a successful malicious attack. In this phase, the pen tester wants to see how much they can “move around” your app and how much access they can gain before the security protocols you have implemented can stop them. 

In some cases, pen testers can not only temporarily access your system but even lurk for weeks and months before you can recognize their presence and do something about it. 

5. Analysis and Reporting 

Finally, pen testers report their finding to you. They will list the specific vulnerabilities they were able to exploit, how much sensitive data was accessed, and any other damage they could do to your application before your team could detect and mitigate the attack. 

Since you’re dealing with an ethical hack and not a malicious one, the pen testers will help you clean up any of the damage and ensure that they haven’t left behind things that could continue to hurt your application, like Backdoor Trojans or altered configurations. 

The full report from pen testers not only outlines the vulnerabilities they found and what damage they were able to cause but also gives a detailed explanation of how they avoided your security protocols.  

Pen Testing Tools

Penetration testers employ a variety of tools for reconnaissance, vulnerability detection, and automating critical aspects of their testing processes, including: 

  • Tools for discovering network hosts and open ports that enable users to write and execute scripts to automate tasks like host discovery and port scanning.

  • Specialized web proxies that intercept and modify traffic between a browser and the target or generic man-in-the-middle proxies that assist in redirecting and inspecting network traffic.

  • Exploitation tools used to achieve system footholds or gain access to targeted assets, which provide a variety of ready-made exploits to test and compromise systems and allow penetration testers to automate the exploitation process.

  • Post-exploitation tools that facilitate interaction with systems, maintaining, and expanding access, and accomplishing attack objectives.

  • Specialized operating systems tailored for penetration testing and ethical hacking. 
  • Credential-cracking programs that can reveal passwords through encryption breaking or brute-force attacks. 

  • Packet analyzers, or packet sniffers, that enable network traffic analysis by capturing and inspecting packets.

Getting Started with Penetration Testing 

If you want to get started on keeping your application secure, Codacy Security is the perfect partner. Our platform helps you scan your application from the inside out with static application security testing (SAST) to identify possible security issues, checking your code against almost security 2,000 rules across 20 languages.

We’ve leveraged the best open-source linters and partnered with the best in the industry to help our customers find and fix issues early in the development lifecycle with a simple and easy-to-use approach.

We also started detecting infrastructure-as-code misconfigurations, helping prevent cloud infrastructure issues. In late 2023, we added secret detection that detects passwords, tokens, and other sensitive hardcoded values in your code. 

To keep your application safe from the inside out, we’ve also partnered with TargetDefense/Bulletproof to provide pen testing services to our customers.

With a Codacy Pro subscription, you get the peace of mind of an additional scan or report required for regulation, affordable pricing with an exclusive discount, and the ability to see unified results back in Codacy. If you are interested, schedule your pen test through Codacy today.


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