Since companies rely more and more on web applications for their core operations, protection against various types of shifting threats and vulnerabilities should be a priority concern. Thus, web application penetration testing should be an indispensable element in protecting any enterprise that develops or manages web-based services and SaaS applications.

Therefore, during a web application penetration test for first-time application developers, a lot of questions can arise: the testing methodologies, what tools are being used, and some common security vulnerabilities that might be inherent in the SaaS application.

To help answer these common questions, we have created this resourceful guide to walk your organization through the process of planning a web application penetration test.

What is web application penetration testing?

Web application penetration testing (also called web app pentesting) is a security assessment aimed at identifying and exploiting vulnerabilities within a web application. This process simulates an attack that may be carried out in the real world, mapping and locating certain weak points that malicious attackers could use.

This is about securing applications for organizations, protecting user data, and keeping it compliant with necessary regulations. The test acts like a general gauge for assurance that the overall security of an application is tightened.

Benefits of web application penetration testing

The following are some key benefits of regular penetration testing to an organization:

  • Identify security flaws: Penetration tests uncover hidden gaps that malicious actors will exploit in the web application.
  • Enhance compliance obligations: A host of laws and regulations, including GDPR and HIPAA, among others, require organizations to perform regular security testing.
  • Minimizes the risk of an attack: Penetration tests minimize the possibility of a breach by exploiting all the different vulnerabilities before an attacker does.
  • Improves the trust of the users: Taking app security seriously shows that a business is committed to protecting its reputation and, by extension, its users’ data and privacy.

Scope of the web application penetration test

Defining the scope is one of the most important preliminary steps for any web application penetration test. A well-defined scope will ensure in all probabilities that each and every area of the application is scrutinized for strong defense against a possible list of vulnerabilities.

The following are the most critical components that usually fall under the scope of web application penetration testing:

Authentication mechanisms

Authentication is the mechanism that allows the identification of a user, usually through a username-password combination. Testing of the authentication mechanisms includes:

  • Ensuring the application can prevent brute-force attacks and that stolen credentials are not reusable.
  • Verifying that multi-factor authentication (MFA), if in use, is properly configured and cannot be bypassed.
  • Determining if the application is enforcing strong password policies regarding minimum length, complexity requirements, and expiration intervals.
  • Ensuring proper session security management, including providing for session expiration, protection against session fixation attacks, and session invalidation following a logout.

Authorization flaws

Authorization controls define which authenticated user has the right to access and changes in the application. An authorized pen tester should verify if each user type (e.g., admin, regular user, guest) can get proper access to resources. Testing for authorization flaws includes:

  • Ensuring users only access functions that are permitted for their role, preventing privilege escalation.
  • Confirming users cannot manipulate URL parameters or object IDs to gain unauthorized access to data, commonly known as Insecure Direct Object References (IDOR). 
  • Performing tests to ensure sensitive pages and data are well protected and inaccessible without proper permissions.

Input validation

Input validation is highly critical to protect the application from attacks that inject malicious code or data. Testing for input validation includes:

  • Ensuring user inputs are sanitized so that malicious scripts won’t be executed in other users’ browsers.
  • Testing for vulnerabilities that allow an attacker to manipulate SQL queries, resulting in information leakage, modification, or even deletion.
  • Testing for vulnerabilities that allow hackers to execute system commands or include arbitrary files.

Error handling and logging

Error handling and event logging are two of the most critical application functionalities in terms of detecting and responding to the web application’s unusual or malicious behaviors. Testing for error handling and logging includes:

  • Ensuring the application does not display technical system error messages to users.
  • Verifying that invalid or abnormal behaviour is logged, including multiple failed login attempts or attempts to unauthorized access.
  • Testing the log tampering protection against unauthorized entities.
  • Ensuring logs do not store sensitive information, including but not limited to plaintext passwords or personally identifiable information (PII), for privacy and compliance reasons.

Web application penetration testing methodology

An infographic showing the 4 main steps of web application penetration testing.

Web application penetration testing employs a methodology that systematically exploits different parts of the application. Normally, the methodology of testing also involves the use of industry standards such as OWASP. The key steps are outlined below:

1. Reconnaissance and information gathering

During this phase, information from the application as well as from its environment is collected. Passive reconnaissance includes searching publicly available data, whereas active methods such as scanning can be performed in order to map the structure of the application.

2. Vulnerability scanning

This phase leverages the use of tools in finding common vulnerabilities. Common misconfigurations, outdated libraries, and unsecured protocols may be picked up through scans.

3. Exploitation

After identifying the vulnerabilities, the tester tries to exploit them. This is hands-on verification of the real impact of every vulnerability in application security.

4. Reporting

When a test is completed, a comprehensive report of the findings, implications, and steps prescribed for remediation is produced.

OWASP methodologies in web app penetration testing

By aligning with methodologies such as OWASP, pen testers can adapt structured and reliable means of finding risks and then mitigating those very vulnerabilities.

OWASP Top 10

The OWASP Top 10 is a list updated on a regular basis, which includes, in order, the most critical security risks concerning web applications. It is used as a benchmark for identifying high-priority vulnerabilities and understanding trends within security risks.

OWASP Testing Guide

The OWASP Testing Guide is an in-depth guide that describes best practices and methodologies concerning web application penetration testing. It first categorizes various test types and then explains each test in a step-by-step manner.

OWASP Application Security Verification Standard (ASVS)

The OWASP Application Security Verification Standard (ASVS) provides a basis on which to establish app security requirements in web applications at different assurance levels. The ASVS is particularly valuable for any organization that needs to check all applications against a well-defined set of uniform security standards or guidelines. 

It has three levels of security assurance:

  • Level 1: Basic security level for low-risk applications.
  • Level 2: Higher security level, where the processing of sensitive data in applications is moderately high-risk.
  • Level 3: The highest security level, designed for critical applications where security is paramount.

Common vulnerabilities in web applications

Vulnerabilities can be introduced by at least one of the following: improper configuration, software implementation weaknesses, and design flaws. 

As already mentioned, OWASP maintains an updated list on the top critical risks, identified as the OWASP Top 10, which is a good reference for the main threats that web applications are facing:

Broken access control

 Poor application of access controls allows unauthorized people to view or modify sensitive data or perform privileged functions. An attacker may be able to exploit this kind of opportunity to take control of other users’ accounts, view people’s data, perform unauthorized actions, or access administrative functions.

Security misconfiguration

 Security settings that are not well configured or left on their defaults, thus making sensitive information and system functions accessible to unauthorized users.

Insecure design

 This addresses vulnerabilities stemming from flawed designs, highlighting the need for proactive security measures grounded in secure design principles as a means of risk avoidance.

Cryptographic failures

 This arises when sensitive data is not well accommodated and the attackers have the potential to intercept financial information, personal data, or business secrets.

Server-Side Request Forgery (SSRF)

 A procedure in which a server is tricked into making requests on behalf of an attacker to improper destinations or systems could result in unauthorized access, information disclosure, or some kind of malicious activity.

Vulnerable and outdated components

 Using outdated or vulnerable software components can lead to severe breaches. This emphasizes the need to update and patch all components, such as libraries and frameworks, regularly.

Identification and authentication failures

 This involves vulnerabilities in procedures for authentication and identity management. Poor password policies, weak session management, and many other weak authentication checks enable the theft of identities or unauthorized access.

Injection

 SQL, NoSQL, or command injection all occur when an application sends untrusted data to an interpreter as part of a command or query. Attackers exploit these types of vulnerabilities to execute unauthorized commands or access unauthorized data.

Software and data integrity failures

 This points out the risks of insecure software updates, insecure CI/CD pipelines, and data integrity issues because of a lack of proper verification that might compromise the system.

Security logging and monitoring failures

 Poor logging practices combined with poor monitoring will delay or prevent the detection of a security breach, which allows attackers to go about their business undetected.

If you’re interested in the list for the OWASP Top 10 mobile vulnerabilities, check out this helpful guide by Verimatrix, which serves as a developer’s guide to securing, detecting and responding to threats targeting mobile apps.

Web application penetration testing standards and frameworks

Consistency and completeness in web application penetration testing are assured by standards and frameworks. The following are some of the most widely adopted standards:

Using these frameworks helps ensure a methodical approach to testing and provides a web application penetration testing guide that testers can rely on for quality assurance.

Commonly used web application penetration testing tools

There are various tools available that can aid in the process of web application penetration testing, such as automating the scanning for vulnerabilities, assisting in reconnaissance, and providing options for reporting. 

Some of the more popularly used web application penetration testing tools include:

  • Burp Suite: A comprehensive tool for testing web applications, including features for scanning, crawling, and vulnerability detection.
  • OWASP ZAP (Zed Attack Proxy): An open-source tool popular for identifying common vulnerabilities.
  • Nmap: A network mapping tool frequently used to discover open ports and services.
  • Nikto: A web server scanner that can identify vulnerabilities, outdated versions, and potentially dangerous files.

Conclusion

Penetration testing for a web application is considered one of the most important activities since it helps in maintaining app security and ensuring compliance. Its advantages range from the identification of hidden vulnerabilities to gaining user trust. 

With well-articulated security policies and a strong incident response plan, penetration testing can be done on a periodic basis. 

If your organization is in need of expert assistance to enhance your app security posture, reach out to a company that has expertise in 24/7 threat monitoring and deep security assessments. Check out Verimatrix XTD.