Web applications have increasingly become the backbone of many businesses, but also, unfortunately, major targets for cyberthreats. The reliance on these applications for various crucial operations — from processing customer data to facilitating e-commerce transactions — makes it imperative to uphold strong security defenses.

According to Verizon’s 2024 Data Breach Investigations Report, web application attacks are involved in 26% of all breaches, making it the second most common attack pattern. Moreover, another recent report found that 72% of vulnerabilities discovered in web apps were related to source code snafus. Along with these oversights, incorrect condition checks and improper configurations can pave the way for many types of attacks, including SQL injections and cross-site scripting (XSS).

With cyberattacks becoming more sophisticated and targeting web applications more frequently, the importance of understanding these vulnerabilities is now more pronounced than ever.

In this post, we will shed some light on the seven most common web application vulnerabilities so you have a stronger understanding of how to protect your digital footprint.

1. SQL Injection

SQL injection (SQLi) attacks occur when attackers exploit vulnerabilities in data-driven web applications by sending specially crafted SQL queries through the application. By injecting malicious SQL queries into form fields that are designed to accept different types of inputs, attackers can manipulate the database to reveal information, alter data, or even execute administrative operations on the database.

The consequences of an SQLi attack can be severe, including:

• Unauthorized viewing of user lists, personal data, and other sensitive information stored in the database.
• Modification and deletion of data, potentially leading to data loss or service disruption.
• Administration operations on the database, such as shutting down the DBMS, issuing commands to the operating system, or even escalating privileges within the context of the database server.

Hackers use automated tools like SQLMap to discover and exploit these vulnerabilities, and this highlights the need for rigorous input validation and parameterized queries as preventive measures.

2. Cross-Site Scripting (XSS)

Cross-site scripting (XSS) is a prevalent web application vulnerability that allows attackers to inject malicious scripts into web pages viewed by other users. This compromises the interaction users have with vulnerable applications.

Unlike other web attacks, XSS targets the users of the website rather than the server itself. The goal is to execute scripts in the victim’s browser that can hijack user sessions, deface websites, or redirect the user to malicious sites.

There are three main types of XSS:

• Stored XSS: The most dangerous type, where the injected script is permanently stored on target servers, such as in a database, in a message forum, visitor log, comment field, etc. The victim retrieves the malicious script from the server when requesting the stored information.
• Reflected XSS: The malicious script comes from the current HTTP request. Here, the user might click a link that contains the malicious URL, or they might be tricked into submitting a form that leads to the XSS attack being triggered. The script is embedded in the response page and executed by the browser.
• DOM-based XSS: This type occurs when the script is triggered due to document object model (DOM) manipulation in a client-side script. It can happen entirely on the client side, where the payload is not processed or stored by the server but is executed due to DOM modification.

The effects of successful XSS attacks can be severe, including:

• Stealing cookies, sessions and other sensitive data that can lead to identity theft.
• Manipulating or destroying data on behalf of the user, potentially causing reputational damage or operational disruption.
• Performing actions on other websites on behalf of the user if the websites rely on cookie-based authentication.

The persistence of XSS in the OWASP Top 10 reinforces the necessity for sanitizing and validating all user inputs to prevent malicious data from being rendered in the browser.

3. Cross-Site Request Forgery (CSRF)

Cross-site request forgery (CSRF) is a web security vulnerability that tricks a web browser into executing an unwanted action in an application to which a user is logged in. Unlike XSS, which exploits the trust a user has for a particular site, CSRF exploits the trust that a site has in a user’s browser.

That is, a CSRF attack occurs when a malicious website, email, blog, or program causes a user’s web browser to perform an unwanted action on a trusted site for which the user is currently authenticated. For example, if a user is logged into their bank account and unknowingly triggers a CSRF attack, this attack can transfer funds, change passwords, or steal the account without the user’s knowledge, essentially riding on the user’s logged-in status.

Anti-CSRF tokens and adherence to the Same-Origin Policy are effective countermeasures against CSRF attacks.

4. Security Misconfiguration

Security Misconfiguration is one of the most common vulnerabilities that affects web applications. It happens when security settings are defined, implemented and maintained improperly.

Such misconfigurations can occur at any level of an application stack, including the network services, platform, web server, database, framework, custom code, and pre-installed virtual machines, applications or storage. The broad spectrum of potential misconfiguration can make it a pervasive and significant risk.

Misconfiguration can happen due to a variety of reasons:

• Default Settings: Continuing to use default configurations or default user accounts and their passwords.
• Incomplete Configurations: Not fully configuring security settings, thereby leaving unnecessary features enabled or unprotected.
• Outdated Software: Running outdated software versions can expose vulnerabilities that have been fixed in later versions.
• Verbose Error Messages: Detailed error messages containing sensitive information that could aid an attacker.
• Unnecessary Services: Services that are not needed by the application but are enabled and accessible.

Here are the types of security misconfigurations that could occur:

• Improper file and directory permissions, allowing unauthorized users to access sensitive files.
• Misconfigured cloud storage that exposes sensitive data to the public.
• Unsecured databases that are not configured with adequate security controls that allow unauthorized access.
• Inadequate or improperly configured HTTP headers can expose the application to attacks like XSS or clickjacking.

Its impacts are varied but can include:

• Unauthorized data access or data loss.
• Service disruption or complete takeover of the application.
• Increased likelihood of more severe attacks, facilitated by the initial exposure due to misconfiguration.

The key to mitigating this vulnerability is a combination of proactive security practices, regular updates, and a culture of security awareness within the organization. Employing secure default settings by changing configurations from their defaults to more secure options during installation and regular operations can significantly lower risks. Regular security audits are essential, as they help in identifying and promptly addressing misconfigurations.

Additionally, the deployment of web application firewalls (aka WAFs) adds a robust layer of security, inspecting incoming traffic and blocking potentially harmful requests, thereby providing real-time protection against the exploitation of misconfigured systems.

5. Insecure Direct Object References (IDOR)

Insecure direct object references (IDOR) occur when an application provides direct access to objects based on user-supplied input. This vulnerability allows attackers to bypass authorization and access resources directly, which can lead to unauthorized access to data or functionality within the application that the user shouldn’t have access to.

IDOR vulnerabilities typically arise when:

• Web applications expose a reference to an internal implementation object, such as a file, directory, or database key, directly in the URL or as an HTML form parameter.
• Insufficient authorization checks are performed when these references are accessed. This allows attackers who can guess or enumerate these references to access unauthorized data.

For example, if a URL to access a user’s banking transactions is formatted as bank.com/account?transaction_id=12345, an attacker might change transaction_id to different values in an attempt to access transactions from other users, exploiting the IDOR vulnerability if proper authorization checks are not in place.

The impact can be severe, depending on the nature of the data or functionality exposed:

• Unauthorized access to personal data such as social security numbers, credit card details, or medical records.
• Unauthorized actions, such as altering data, processing transactions, or changing permissions.
• Data breaches, leading to regulatory fines and significant damage to reputation.

To combat IDOR, applications should implement robust authorization checks and avoid exposing direct references to internal objects. Ensure that each request to access a resource is accompanied by an authorization check to verify that the user has the right to access the requested resource. Utilize role-based access control (RBAC) mechanisms to enforce who can access what resources under which conditions.

6. Broken Authentication

Broken authentication typically results when security measures related to the authentication process are implemented incorrectly, allowing attackers to compromise passwords, keys, and session tokens, or exploit other implementation flaws to assume other users’ identities. This vulnerability can lead to unauthorized access and control of critical functions or sensitive data within a system.

Broken authentication can occur through various mechanisms:

• Credential Stuffing: Where attackers use stolen account credentials in large-scale automated login requests directed against a web application.
• Session Hijacking: This occurs when a user’s session token is stolen and used by an attacker to gain unauthorized access to the application.
• Insufficiently Protected Credentials: Poorly implemented encryption or hashing of passwords and security answers allows attackers to easily decrypt or guess credentials.
• Lack of Multi-factor Authentication (MFA): Relying solely on usernames and passwords without a second form of verification increases vulnerability to credential theft.

The impacts are severe and can include:

• Unauthorized access to user accounts.
• Data breaches involving sensitive, regulated, or proprietary information.
• Gaining elevated privileges within the system, potentially leading to full system control.

To prevent broken authentication, enforcing strong password policies is crucial; this involves requiring complex passwords that need to be regularly updated and cannot be easily guessed. Adding layers to the authentication process enhances security significantly, hence the importance of implementing multi-factor authentication (MFA). MFA requires users to provide multiple verification factors, which dramatically reduces the likelihood of unauthorized access.

Another key area is session management. Ensuring that session IDs are both strong and unique and that they are promptly invalidated upon the user logging out or after a certain period of inactivity, helps in preventing session hijacking. Alongside this, encrypting or hashing credentials securely protects user data even if unauthorized access to the database occurs. Conducting regular security audits and vulnerability testing is another critical measure, helping to identify and remediate potential security weaknesses before they can be exploited.

7. Using Components With Known Vulnerabilities

There is an added risk introduced when software applications utilize libraries, frameworks, or other modules that have known security flaws. This vulnerability can arise from failing to keep these components updated or by using outdated components that no longer receive security updates from their maintainers.

This issue typically occurs in the following contexts:

• Outdated Libraries and Frameworks: Often, projects will include third-party libraries during development. Over time, these may become outdated as new vulnerabilities are discovered, but if they aren’t updated, they can expose the application to attacks.
• Transitive Dependencies: Modern applications often use packages that, in turn, depend on other packages. Vulnerabilities in any part of this dependency chain can compromise the entire application.
• Lack of Software Inventory: Without a clear inventory of the third-party components used in an application, it’s difficult to track which components are vulnerable and need updates.

Here are a few examples of vulnerable components:

• Libraries like Apache Struts, that had a significant vulnerability that led to high-profile breaches.
• Outdated content management systems like certain versions of WordPress or Joomla are known to be insecure.
• Network services like older versions of OpenSSL which had critical vulnerabilities like Heartbleed.

To prevent the exploitation of known vulnerabilities in software components, regular updates and patching are crucial. All software components, from the operating system to application libraries, must be kept up-to-date with the latest security patches. This proactive approach not only remediates identified vulnerabilities but also helps in maintaining the overall security hygiene of the software environment.

Additionally, the use of software composition analysis tools plays a pivotal role in safeguarding applications. These tools are designed to scan codebases for known vulnerabilities within components, helping maintain an up-to-date inventory of third-party dependencies and their security statuses. This is crucial for identifying and mitigating risks before they can be exploited by malicious actors.

Also, effective vendor management ensures that all third-party components integrated into the software come from reputable sources and are supported over the long term. It is vital to verify that these components receive continuous updates and support to protect against emerging threats.

Best Practices for Securing Web Apps

Securing web applications is a continuous process that requires you to implement some established best practices and stay updated with new security advancements. Here are three simple strategies for protecting web applications from common vulnerabilities and attacks.

1. Using web application firewalls (WAFs)

A web application firewall is an essential tool in protecting web applications from known vulnerabilities and attacks.

WAFs operate by filtering, monitoring, and blocking harmful HTTP traffic to and from a web application. They help defend against SQL injections, XSS attacks, and other OWASP Top 10 threats by examining the traffic before it reaches the application and blocking harmful requests based on specific rulesets.

2. Regular security assessments and penetration testing

To identify vulnerabilities that could be exploited by attackers, regular security assessments and penetration testing are crucial. These practices involve the evaluation of the system for potential security breaches and vulnerabilities.

Penetration testing, in particular, simulates real-world attacks to test the effectiveness of existing security measures. It helps organizations find and fix security vulnerabilities before they can be exploited.

3. Emphasizing secure coding practices and continuous education

Secure coding practices are vital for reducing the number of vulnerabilities in web applications. Developers must be trained in secure coding techniques which involve input validation, output encoding, proper error handling, and the use of security features provided by the development frameworks. Secure coding also encompasses the principles of least privilege and defense in depth, ensuring that applications have multiple layers of protection.

Keeping development and security teams informed about the latest security threats and mitigation techniques is crucial. Continuous education on security best practices, new vulnerabilities, and defensive tactics help in maintaining a secure development lifecycle. This ongoing learning process can be supported through regular training sessions, security workshops, and updates on the latest security trends.

Wrapping Up

While the task of securing web applications is undoubtedly complex, it is also entirely manageable with the right approach and resources. By understanding the common vulnerabilities, applying best practices, staying adaptive to new threats and fostering a security-aware culture, you can significantly enhance their defensive posture against the range of cyberthreats facing modern web applications.