Common Web Application Vulnerabilities + How To Prevent Them

Security breaches are surprisingly common in the world of website applications. In fact, a recent study found that hackers attacked users in 9 out of 10 web applications in 2019 alone.

In order to protect your customers’ data from being stolen while maintaining a positive brand reputation, it’s vital to understand the most common web application vulnerabilities, and know how to prevent security breaches.

In this article, we’ll cover the latest web application vulnerabilities, explore prevention methods and share tips to help you strengthen your web application security as well as preventing any issues in app or hybrid app development.

The most common web application vulnerabilities include:

  1. SQL Injection
  2. Broken Authentication
  3. Cross-Site Scripting (XSS)
  4. Broken Access Control
  5. Cross-Site Request Forgery (CSRF)
  6. Session Hijacking
  7. Distributed Denial Of Service (DDoS) Attack
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What Are Web Application Vulnerabilities?

Web application vulnerabilities are weaknesses or system flaws in web-based applications that can be exploited by a person who performs security breaches, known as a threat actor.

Web application vulnerabilities allow threat actors to access your system so they can perform unauthorized actions, such as leaking sensitive data or stealing passwords.

7 Common Web Application Vulnerabilities

From injecting malicious code into your web application to hijacking a user’s session, here are seven of the most common web application vulnerabilities to look out for.

1. SQL Injection

Structured Query Language (SQL) injection occurs when malicious SQL code is inserted into your database, so threat actors can access sensitive information such as company data, log-in credentials and stored credit card information.

Structured Query Language is a computer language used to program and manage data on web applications.

Once hackers successfully inject malicious code, they can issue commands to your operating system to read sensitive data on your database and modify or delete data.

A common web application vulnerability, SQL injection represented 65% of web application cyber attacks in 2019.

2. Broken Authentication

Broken authentication is a broad term that refers to a threat actor utilizing a web application’s inadequate password policy or unlimited log-in attempts to hijack a user’s account.

Broken authentication attacks aim to impersonate an authenticated user to compromise or modify passwords and steal user data, such as personal names and credit card information.

According to the OWASP Top 10 list of top web application vulnerabilities, broken authentication jumped to the #1 spot in 2021 from 2017, where it ranked #5.

If your web application has a relaxed password policy and allows multiple login attempts, there’s a greater chance that a threat actor can access accounts.

A relaxed password policy allows users to set easy-to-guess passwords such as “123456,” while allowing multiple login attempts increases the chance of gaining access to an account.

3. Cross-Site Scripting (XSS)

Similar to an SQL injection, cross-site scripting involves inserting malicious code into a website application.

For example, when malicious code is injected into your web app and a threat actor hijacked your user’s session — the threat actor can access any session tokens and sensitive data retained by your user’s browser.

During a cross-site scripting attack, a threat actor can:

  • Hijack a user’s session
  • Direct a user to dangerous websites
  • Infect a user’s JavaScript to steal cookies and sensitive data

4. Broken Access Control

A broken access control occurs when a hacker is able to read, modify or delete data beyond their account’s capabilities due to a system error.

Access controls identify how users can interact with data, such as what they can view or modify.

For example, let's say your web application only grants access to payment details. If broken access control occurs, hackers can edit payment details as well.

Threat actors use this web application vulnerability to access networks, systems and software. In addition, they can access admin privileges such as viewing customer data, credit cards and passwords.

5. Cross-Site Request Forgery (CSRF)

A cross-site request forgery (CSRF) attack forces a user to perform unwanted actions on a web app by utilizing social engineering attack tactics, such as clicking on links from phishing mails.

When a user clicks on a link from a phishing mail, the hacker is granted access to account information. The hacker can then change passwords, user names or transfer funds in a web application like PayPal.

Unlike a cross-site scripting (XSS) attack, a CSRF attack requires the user to be logged into a web application that uses session cookies for validating user requests and tracking sessions.

A popular target for CSRF attacks is online money transfer web applications.

For example, cookies store personal data (your name, login credentials and email address) in PayPal accounts. Once a hacker gains access to your PayPal account — without multi-factor authentication verification — they can seamlessly transfer funds out of your account.

6. Session Hijacking

Session hijacking is a technique hackers use to hijack a user’s session on web applications.

Website applications that require user accounts typically implement an authentication process to identify returning users.

Once the user is authenticated, a session will be established. The server and user’s browser exchange a session ID, so the server knows which user is accessing the web application.

If a hacker gains access to a user's session ID, they can use their bank account to transfer money, purchase items on THE user’s behalf and steal data.

7. Distributed Denial Of Service (DDoS) Attack

Living up to its name, a distributed denial of service attack occurs when a web application or network becomes temporarily or indefinitely unavailable.

DDoS attacks occur when a threat actor floods a web application or network with too much traffic, until the web application crashes. Once a threat actor performs a DDoS attack, the website application slows down or cannot be accessed by authenticated users.

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How To Prevent Common Web Application Vulnerabilities

Now that you’re aware of the common web application vulnerabilities, here are cybersecurity tips on how to prevent them from occurring.

1. How To Prevent SQL Injection

To prevent SQL injection attacks:

Enable input sanitization: Input sanitization is a cybersecurity protocol of assessing, cleaning and filtering data inputs from APIs, users, and web services of any unwanted characters and strings, to prevent harmful codes being injected into your web application.

Install a website application firewall: A web application firewall monitors your web application’s traffic and identifies patterns that pose a threat.

2. How To Prevent Broken Authentication

To prevent broken authentication:

  • Reject weak passwords: When developing your password policy, set stringent password requirements, such as a certain length and complexity. Standard password requirements include a minimum password length of eight characters, with a mix of special and alphanumeric characters.
  • Limit login attempts: Hackers might try brute force or guessing as many passwords as they can to hack an account. To prevent this, enforce a limit of login attempts before locking out your user. For example, set a maximum of three login attempts.

3. How To Prevent Cross-Site Scripting (XSS)

To prevent cross-site scripting:

  • Utilize a content security policy: Use a content security policy (CSP) to mitigate the consequences of a potential cross-site scripting attack. Think of this policy as an added layer of protection to help detect and mitigate cross-site scripting (XSS) and data injection attacks.
  • Scan your web application regularly: For preventive measures, regularly scan your web application using a web vulnerability scanner.

4. How To Prevent Broken Access Control

To prevent broken access control:

  • Set up access control lists: Access control must operate on the server-side by setting up Access Control Lists (ACL) or a list of rules that specifies which users are granted or denied access to a particular system resource.
  • Deny access by default: In the development stage, you can deny users access to fields, functionalities and pages that they shouldn’t’ have access to by setting their accounts with minimum privileged functions. For example, by default, every user should be restricted from modifying data they only need to view.

5. How To Prevent Cross-Site Request Forgery (CSRF)

To prevent cross-site request forgery:

  • Send phishing email reminders: Remind users not to click on any suspicious links, especially since 96% of phishing attacks occur through email. Educate your users on how to spot a phishing email by fact-checking the sender’s email address and watching for grammar mistakes.
  • Enable multi-factor authentication: Let’s say a hacker was able to hijack your user’s account. While the hacker was able to scratch the surface by logging into the account, multi-factor authentication adds multiple layers of protection on top of a password. Assuming that the hacker doesn’t have your user’s mobile device to receive the code from MFA, your user’s account is still safe.

6. How To Prevent Session Hijacking

To prevent session hijacking:

  • Enable session timeout: To further safeguard your user’s data, you can enable a session timeout where you automatically log your user out after a certain time frame (for example, 15 minutes) if their web application can sense that your user is inactive during their session. As the session timeout approaches, you can notify your user that their session is almost up and give them a choice to stay logged in. For example, “Your online banking session is about to expire. Please choose Continue Session to stay logged in.”
  • Encourage two- or multi-factor authentication: Further verification steps act as an added layer of protection, even if your user’s account gets hijacked.

7. How To Prevent Distributed Denial Of Service (DDoS)

To prevent distributed denial of service attacks:

  • Subscribe to DDoS protection services: DDoS protection services identify abnormal traffic flows and redirect abnormal traffic from your web application.
  • Craft a disaster recovery plan: A recovery plan outlines how you’ll communicate the problem, mitigate it, and how you’ll recover after the attack. Creating a plan ahead of time can help you react quickly if or when a DDoS attack occurs.
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Tips To Improve Your Web Application Security

Interested in further streamlining your web application’s security?

Follow our top tips to ensure your users’ data is protected from web application vulnerabilities.

1. Ensure Your Data Is Encrypted

When a user visits and uses your web application, they share sensitive data such as their login credentials.

Typically, data sent between web applications and web servers are sent in plain text, which can leave data vulnerable to eavesdropping — where hackers depend on unsecured networks to access data in transit between devices.

To prevent eavesdropping, utilize the transport layer security (TLS) protocol.

Transport Layer Security (TLS) is an encryption security protocol you can use to prevent hackers from eavesdropping on your users’ data.

The TLS protocol uses symmetric and asymmetric encryption to protect sensitive data.

Symmetric encryption exchanges data within a secured session, while asymmetric encryption establishes a secure session between the user and web server.

2. Implement A Strong Password Policy

A strong password policy prevents hackers easily guessing passwords.

From guessing passwords using brute force to using social engineering, cyber criminals have developed various methods and tools over the years to crack passwords in seconds.

A strong password requires the following criteria:

  • Must be at least 12 characters long
  • Must not contain your user’s personal information such as real name, maiden name or birth date
  • Must be unique from your user’s previously used passwords
  • Must contain different types of characters, including lowercase and uppercase letters, numbers and symbols

Ultimately, common passwords such as “123456” and “qwerty” are a big no-no.

3. Encourage Two-Factor Or Multi-Factor Authentication

A two-step factor verification, also known as 2FA, is a security process that adds a second layer to your users' accounts in addition to passwords.

The same logic applies to multi-factor authentication or MFA, but with more security layers than 2FA.

Think of two- or multi-factor authentication as an additional wall of defense to secure your user’s data from threat actors.

PayPal is a good example of a web application that encourages two- and multi-factor authentication.

Their two-step verification process allows you to choose between getting a code through text or using an authenticator app to receive a code after entering your password. The code then expires after 10 minutes.

So, even if a hacker guesses your password correctly, they won’t gain access to your account, unless they have your mobile device to receive the code.

4. Partner With Cybersecurity Experts

Partnering with a cybersecurity consulting firm ensures your website application is secure from potential cyber attacks.

Cybersecurity consulting firms monitor your website application, determine your web app's current and potential vulnerabilities and consistently implement updated security features to keep your data — and your brand reputation — safe.

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Wrapping Up On Web Application Vulnerabilities

Understanding the latest web application vulnerabilities and knowing how to prevent them will give your website application a strong line of defense against hackers.

While threat actors have developed many tools and processes to steal data through your web application, here are tips on how you can improve your web application security to protect your brand and users:

  • Ensure your data is encrypted
  • Implement a strong password policy
  • Encourage two- or multi-factor authentication
  • Partner with cybersecurity experts
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