Web applications come in all shapes and sizes – from simple contact forms to social media platforms to online banking systems. They all have one thing in common: they handle valuable data.
Like a bank vault, your web apps should be tested to find vulnerabilities as soon as possible so you can fix them before they can be exploited by hackers. To do this, you need a comprehensive testing methodology that can cover all the bases.
1. Cross-site scripting
Cross-site scripting (XSS) is a type of security vulnerability that involves code injection into a web page or application. XSS attacks can result in malicious code being executed in the user’s browser, which can allow hackers to access sensitive information such as session cookies or other data that has been stored by a browser on behalf of an authenticated user.
XSS vulnerabilities are typically exploited by cybercriminals who want to steal personal information, including bank account numbers and other sensitive details that can be used for identity theft or fraudulent transactions. Often, attackers use phishing or social engineering to trick victims into visiting a malicious URL.
Many websites use JavaScript to perform a variety of functions, such as displaying advertisements and sending users data to other websites. This has made JavaScript a popular and common language for modern web development, but it also brings with it a range of unique vulnerabilities.
For example, JavaScript is a language that can be easily altered by hackers, which is why cross-site scripting attacks are one of the most widespread and prevalent security vulnerabilities. These attacks are mainly focused on stealing credentials that have been saved by a user’s browser, such as their username and password.
Most browsers have built-in security features that can block XSS and other attacks. However, even when these tools do work, they are only able to prevent the threat from being spread across all pages on a website.
The most effective way to protect a site from XSS is to ensure that any unsafe inputs are sanitized before being rendered into HTML and served on a web page. This can be done by restricting user input to a specific allowlist or by ensuring that only known safe values are sent to the server.
Another important factor is implementing strong coding practices that limit the possibility of XSS attacks. For example, JavaScript should be compiled into object-oriented code rather than interpreted as plain text.
A third factor is the use of content security policies (CSPs) in web applications. CSPs can help to mitigate XSS by preventing the exploitation of vulnerable code by blocking certain commands from executing within the browser.
2. SQL injection
When an attacker exploits a SQL injection vulnerability, he or she can take control of the backend database and retrieve information that wasn’t intended to be displayed on the front end. This includes sensitive company data, user lists or private customer details.
To mitigate the risk of a SQL injection attack, organizations need to ensure that all developers and testers are well-versed in web application security testing. They also need to regularly scan their applications using a web vulnerability scanner, such as Acunetix.
The best way to prevent SQL Injection attacks is to validate user-supplied input, especially input fields that can be accessed by the user. For example, a form that allows users to enter login information should also verify the credentials and allow users to change their passwords.
In addition, it’s essential to configure proper error reporting and handling on the web server and in the code so that database error messages never reach the client web browser. This helps to reduce the chance of an attacker leveraging technical details in verbose error messages for successful exploitation of an SQL Injection flaw.
It’s also important to use parameters any time you need to make an SQL query to a database, entering placeholder values in your statements and then passing user-inputted values to the statements at the time of execution. If your programming language does not support parameters, then you should remediate your application by sanitizing or escaping input before passing it to a database.
As part of a comprehensive web application security strategy, you should test all your web pages for SQL injection vulnerabilities during development and then continuously through production. You should also regularly update your software and frameworks with patches for discovered vulnerabilities.
In addition, you should provide suitable security training to all your developers, QA staff and DevOps employees. These security trainings can help prevent the recurrence of SQL injection attacks and other security vulnerabilities in your web application. Additionally, you should regularly scan your web applications with a web vulnerability scanner such as Acunetix to identify any potential SQL Injection vulnerabilities and fix them quickly.
3. Cross-site request forgery (CSRF)
CSRF vulnerabilities exploit the trust web applications have with users to send forged requests that perform actions on behalf of the authenticated user. These unauthorized operations can include transferring funds, changing a user’s email address, and gaining access to sensitive data, among others.
Unlike reflected XSS, which is primarily a UI vulnerability, CSRF focuses on state-changing requests that the attacker can execute without the victim’s knowledge. The attack may also involve social engineering, such as sending an email or website link to a victim and having them click on it.
The underlying principle behind cross-site request forgery is that when a client makes an HTTP request to a server, it automatically includes any cookies and other tokens that it has received from the domain of the server. These automatically included cookies and tokens are often used by a CSRF attacker to cause the client to send a forged request that appears real and then performs any requests appropriately (for example, transferring funds or changing a user’s email address).
Some developers will protect against CSRF using methods that distinguish between legitimate and malicious requests by comparing a random, unique token generated by the server with the expected value in each request. These are known as synchronizer tokens, and are considered the best protection against CSRF attacks.
Another way to mitigate CSRF is to make sure that all browsers support SameSite cookies, which prevent web applications from sending forged cookies and tokens to the web servers of other domains. This works because browsers will invisibly include any cookies and tokens that they receive from a given domain in any web request sent to that domain.
This method of preventing CSRF is especially effective on web applications that use session cookies, because these cookies and tokens are automatically included in any request sent to the domain of the server. However, it is important to note that this strategy will only protect the application against CSRF vulnerabilities if the web applications are designed properly and implemented correctly.
The best way to avoid CSRF attacks is by using the synchronizer token technique and by making sure that all users use modern, updated web browsers that support SameSite cookies. Moreover, ensuring that all users are logged in at all times is a good safeguard against CSRF attacks, and should be considered a basic security policy for every company.
4. Denial of service (DoS)
A DoS (denial of service) is an attack that makes a system or network inaccessible. It typically happens when an attacker floods the system or network with unwanted traffic. This can make it impossible for users to access information or services, causing it to crash and costing businesses time and money.
There are many different kinds of DoS attacks, ranging from simple one-system saturating floods to massive distributed denial-of-service (DDoS) attacks that involve hundreds of thousands of attacking systems. However, the majority of modern-day DoS attacks rely on a significant number of attacking systems coordinated under the control of a single attacker to overwhelm the target.
This can be accomplished by either exploiting a software vulnerability in the system or flooding it with fake requests, both of which consume excessive amounts of network resources. The most common type of DoS attack is a volumetric attack, which seeks to saturate the target’s bandwidth capacity by overwhelming it with traffic that exceeds its bandwidth limit.
Another popular DoS attack is application-targeted, which targets a specific application and makes demands that stress its components. This can include preventing users from using the application, locking them out of their accounts or making requests that demand an entire database that it depends on to perform its normal functions.
The attack can be bolstered by using a malicious script or exploit that facilitates direct system access. For example, it could be used to lock out user accounts after a series of failed login attempts or to force the application to reload itself after an error condition is triggered.
A DoS attack can be detected via monitoring and analysis of network traffic, as well as detecting anomalous changes in the load on a system. This can alert the system owner to a DoS attack and help prevent it from happening in the first place.
Keeping up with best practices and following security guidelines can protect your web application from these kinds of attacks. These measures include reviewing application architecture and implementation, monitoring network traffic and analyzing traffic origins and types. They also include implementing good security habits, such as limiting user actions that can overload system resources and regularly evaluating system health and responsiveness.
