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Web Application Security: Threats and 6 Defensive Methods

March 16, 2022
Oliver Moradov

What Is Web Application Security?

Web application security is the practice of detecting and preventing cyber attacks on websites, and more importantly—building websites that are secure to begin with. This includes a set of security controls built into web applications to protect them from a growing variety of cyber threats.

Web applications inevitably contain bugs and misconfigurations, and some of these are security vulnerabilities that can be exploited by attackers. Web application security helps address these vulnerabilities by leveraging secure development practices, implementing security testing throughout the software development lifecycle (SDLC), resolving design-level defects and avoiding security concerns during deployment and runtime.

In this article:

Why is Web Security Testing Important?

Web security testing focuses on identifying security vulnerabilities in web applications and their configurations. Its primary objective is the application layer. Testing web application security often involves delivering various input types to provoke errors and cause unexpected system behavior. These “negative tests” investigate whether the system is performing tasks it isn’t designed to execute.

Additionally, web security testing extends beyond evaluating the security features, such as authentication and authorization, implemented in the application. It’s equally significant to test other features for secure implementation, for example—business logic, proper input validation, and output encoding.

Learn more in our detailed guide to web application security testing.

Top Web Application Security Risks 

Here are some of the major risks facing web applications today.


This security risk occurs when untrusted data is sent to an interpreter via a command or query. An attacker injects malicious code that looks like normal code, and can trick the interpreter into executing unexpected commands or accessing data without proper permissions.

An injection attack on a web application can bypass authorization mechanisms, resulting in exposure of valuable data or complete compromise of the system. Common injection flaws include LDAP, NoSQL, and SQL injection.

Learn more in our detailed guides to:

Denial of Service (DoS) and Distributed Denial-of-Service (DDoS)

In a DoS attack, attackers generate fake traffic through different vectors to overload the target server or surrounding infrastructure. If the server cannot handle incoming requests efficiently, it slows down and eventually refuses to process incoming requests from legitimate users. A DDoS attack is the same thing at a much larger scale, leveraging botnets of thousands or millions of devices controlled by the attacker.

Related content: Read our guide to security testing tools.

Cross-site Request Forgery (CSRF)

CSRF tricks victims into making unwanted requests, leveraging existing authentication. An attacker can use the user’s account privileges to impersonate the user and perform operations on their behalf.

If a user account is compromised, an attacker can steal, destroy, or modify sensitive information. Attackers typically target accounts with high privileges, such as accounts belonging to administrators or executives.

Related content: Read our guide to web application attacks.

Cross-Site Scripting (XSS) 

XSS allows hackers to inject client-side scripts into web pages to intercept user session access, impersonate users, access sensitive information, tamper with websites, or redirect URLs to malicious websites. This flaw occurs whenever an application embeds untrusted data in a web page, or updates a website with user inputs via browser-generated HTML or JavaScript, without proper validation.

Learn more in our detailed guide to web application vulnerabilities.

Security Misconfiguration

This is one of the most common risks to web applications. It occurs when security controls are not set correctly in a web application or the surrounding infrastructure. 

For example, security configuration errors can be unpatched known vulnerabilities, cloud storage exposed to the Internet with no authentication, insecure default configurations left as-is, misconfigured HTTP headers, or unnecessarily detailed error messages that divulge sensitive information to attackers.

Application security professionals must ensure the secure configuration of all applications, frameworks, operating systems, and libraries. It is important to ensure that these are also updated and patched in a timely manner.

Learn more in our detailed guide to websocket security.

XML External Entities (XXE) 

Many web applications have misconfigured XML processors, which evaluate external entity references in XML files. An attacker can exploit external entities to expose internal server files, perform internal port scanning, use a web server for denial of service (DoS) attacks, and perform remote code execution.

Learn more in our detailed guide to XXE

Vulnerable Deserialization

Deserialization is the process of recreating data objects from a stream of bytes. Insecure deserialization occurs when untrusted code, created by an attacker, exploits vulnerabilities in the programming language’s deserialization mechanisms. In severe cases, this can enable remote code execution (RCE). Even if the vulnerability does not lead to RCE, it might still be exploited to perform escalation of privileges, code injection attacks, and replay attacks.

Learn more in our detailed guide to deserialization

Tools You Can Use to Defend Against Web Application Threats

There are two main methods to defend against web application vulnerabilities—prevention or blocking. Ideally, organizations should employ both methods.

Here are key tools to help prevent web application vulnerabilities:

  1. Static application security tests (SAST)—involves analyzing the application source code during development. SAST tools help detect coding and design issues that can lead to vulnerabilities. Learn more in our guide to SAST
  2. Software composition analysis (SCA)—involves analyzing applications to identify open source software (OSS) and third-party components containing known vulnerabilities or licensing restrictions. 
  3. Interactive application security testing (IAST)—involves observing application behavior, such as input, output, data flow, and logic. It requires deploying an IAST agent in the application to conduct a runtime analysis of the code, data flow, and memory. 
  4. Dynamic application security tests (DAST)—involves analyzing code in runtime, including servers and underlying application frameworks. It requires a manual configuration of the DAST for each application. Learn more in our guide to DAST

Here are key tools to help block web application attacks:

  1. Web application firewall (WAF)—protects web applications against malicious HTTP traffic. It places a filter barrier between attackers and the targeted server to block attacks such as SQL injection, CSRF, and XSS. 
  2. Runtime application self-protection (RASP)—detects and blocks attacks by employing in-application instrumentation. You can use an SDK to integrate RASP directly into your codebase or deploy an agent to the host at runtime. 

Related content: Read our guide to microservices security.

6 Web Application Security Best Practices

1. Execute Input Validation

Effectively validating user inputs is crucial for mitigating web application security threats like SQL injection and cross-site scripting (XSS). Verify all data submitted to your application for type, length, format, and range before processing to prevent attackers from injecting malicious code into your system.

Related content: Read our guide to web application attacks.

2. Employ Up-to-Date Encryption

Implementing Transport Layer Security (TLS) with the latest recommended cipher suites and protocols is essential for secure data transmission. Keep TLS configurations current to maintain robust encryption standards.

In addition to TLS for data transmission, securely storing user passwords is important. Use strong cryptographic hash functions like SHA-256 or SHA-512 for password encryption before adding them to your database.

3. Enhance Authentication and Authorization

Implement advanced authentication methods like multi-factor authentication (MFA) to ensure authorized access to your web applications. Set complex password requirements and limit failed login attempts to safeguard against brute force attacks. Implement role-based access control (RBAC) mechanisms to provide the appropriate permissions based on users’ roles within the organization.

Learn more in our detailed guide to web application scanning.

4. Track API Usage

APIs are essential in modern web applications but may introduce security vulnerabilities if improperly managed. Ensure all APIs used in your application have adequate authentication and authorization measures and communicate through encrypted channels. Monitor API usage routinely and analyze access logs for unusual activity or potential vulnerabilities.

5. Record Code Changes

Maintaining accurate records of code changes is crucial for monitoring updates, bug fixes, and new features in your web application. This practice fosters transparency within development teams and helps swiftly identify potential security problems caused by recent modifications. Use version control systems like Git to enable efficient developer collaboration while maintaining a structured history of code adjustments.

Related content: Read our guide to websocket security.

6. Employ Dynamic Testing for Application Security Validation

Using dynamic testing with tools like DAST is another best practice for web application security. Dynamic testing tools can detect numerous issues such as injection attacks, cross-site scripting (XSS), broken authentication and session management, insecure direct object references, and more. Incorporate DAST into all development lifecycle stages, from early testing and staging to production, for shifting security left.

Learn more about SAST in our detailed guide to snyk cli.

Securing Web Applications with Bright Security

Bright is a developer-first Dynamic Application Security Testing (DAST) scanner that can test your applications and APIs (SOAP, REST, GraphQL), enabling you to bake security testing across your development and CI/CD pipelines. 

Detect the OWASP (API) Top 10, Mtre 25 and more, including Business Logic Vulnerabilities. You can easily reduce your security and technical debt by scanning early and often, on every build, to be secure by design. 

Learn more in our detailed guide to mobile security.

With NO false positives, there is no need for manual validation of security findings, removing costly and time consuming human bottlenecks that cripple your rapid releases and drain your security team’s limited resources. 

See Additional Guides on Key Security Testing Topics

Together with our content partners, we have authored in-depth guides on several other topics that can also be useful as you explore the world of security testing.

Cloud Native Security

Authored by Tigera

Application Security Testing

Authored by Bright Security 


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