DEV Community

Ajith Nagappan
Ajith Nagappan

Posted on

What are some of the common vulnerabilities in web applications?

A web application vulnerability is a misconfiguration or weakness in a web application code that allows hackers or attackers to gain some level of site dominance and possibly the hosting server.

Most vulnerabilities are recognized through automated means, such as by using vulnerability scanners and botnets.

Cybercriminals generate specialized tools that scour the internet for particular platforms, like WordPress or Joomla, looking for common and reported vulnerabilities. Once found, these vulnerabilities are exploited to steal data, distribute malicious content, or inject defacement and spam content into the vulnerable site.

Most of the web application vulnerabilities occur due to programming errors. This happens due to negligence during the software development and testing process or from the continuous use of open-source components. .

Web application vulnerabilities can be classified as three categories:

High severity
Medium severity
Low severity

High-Severity Vulnerabilities

High severity vulnerabilities commonly occur in web applications and allow an attacker to easily hack the targeted applications without any direct access to company logins or authentications.

Attackers conducting this type of attack have some technical skills, but many tools make the exploitation process automated.

Most common high severity vulnerabilities are:

Cross-site Scripting
SQL Injection
Remote Code Execution
File Inclusion and Directory Traversal

Cross-site Scripting

Cross-site Scripting is one of the most common vulnerabilities in web applications. Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into otherwise benign and trusted websites.

XSS attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser side script, to a different end-user. Flaws that allow these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user within the output it generates without validating or encoding it.

An attacker can use XSS to send a malicious script to an unsuspecting user. The end user’s browser has no way to know that the script should not be trusted, and will execute the script because it thinks the script came from a trusted source.

The malicious script can access any cookies, session tokens, or other sensitive information retained by the browser and used with that site.

Types of Cross-site Scripting:

Reflected Cross-Site Scripting

Stored Cross-Site Scripting

DOM-based Cross-Site Scripting

Impact of XSS vulnerability include:

Admin account takeover
Read private message
Hijack the session, browser of the user using malware

SQL Injection

SQL injection is a code injection technique that might destroy your database.

SQL injection is one of the most common vulnerabilities in web applications. SQL code injection is a technique where the user input is interrupted as SQL commands rather than standard data while processing the SQL query.
SQL injection exploits by an attacker to access, modify, and delete data from the database. This type of vulnerability allows the attacker to increase to more damaging attacks inside the networks where the application hosts.

SQL injection exploits by an attacker using different strategies based on their categories,

In-band SQL Injection
Blind SQL Injection
Out-of-band SQL injection

In-band SQL injection

In-band SQL Injection is the most common and easy-to-exploit of SQL Injection attacks. In-band SQL Injection occurs when an attacker can use the same communication channel to both launch the attack and gather results.

In-band SQL injections are,
Error based SQL injection

Union Query SQL injection

Inline Query SQL injection

Stacked Queries SQL injection

Blind SQL injection
Blind SQL injection is commonly known as unlike in-band SQL injection or Inferential SQL injection. This type of injection takes longer for an attacker to exploit. Blind SQL injection is the most dangerous than any other form of SQL injection. The attacker is not able to see the reports of these attacks, so this attack is commonly referred to as blind SQL attacks. The attacker in this attack tries to construct a separate database inside the application.

The following types of injection attacks come under blind SQL injection:

Boolean based Blind SQL injection

Time-based Blind SQL injection

Out-of-band SQL injection
Out-of-band SQL injection is an injection attack that is rarely used by an attacker. The possibility of this attack depends on the features enabled in the database of the server. Out-of-band SQL injection is an alternative for time-based SQL injection. These attacks will also occur when the server is not giving a stable response.

Remote Code Execution

Remote Code Execution is one of the most common vulnerabilities in web applications. Remote Code Execution is a vulnerability that can be exploited if user input is injected into a File or a String and evaluated by the programming language's parser error.

Usually, this behavior is not intended by the developer of the web application. A Remote Code Evaluation can lead to a full compromise of the vulnerable web application and also a web server. It is important to note that almost every programming language has code evaluation functions.

Impact of Remote Code Execution

An attacker who can execute such a flaw is usually able to execute commands with the privileges of the programming language or the web server. In many languages, he can issue system commands, write, delete or read files or connect to databases.

Medium-Severity Vulnerabilities

Medium Severity Vulnerabilities usually arise because of errors and deficiencies in the application configuration. By exploiting these security issues, malicious attackers can access sensitive information on the application or server. The exploitation of these types of vulnerabilities can depend on the existence of some special conditions.

For example, in the case of SSL/TLS certificate issues, or misconfiguration of TLS, an attacker has to be in an appropriate location to be able to eavesdrop on the connection of the victim.

Denial of Service (DoS) attacks may occur due to these vulnerabilities.

Medium-Severity flaws include:

Cross-Site Request Forgery

Transport Layer Security (TLS)

Secure Socket Layer (SSL)

Cross-Site Request Forgery (CSRF)

Cross-Site request forgery is one of the most common vulnerabilities in the web application. Cross-site request forgery (CSRF), also known as XSRF, Sea Surf, or Session Riding, is an attack vector that tricks a web browser into executing an unwanted action in an application to which a user is logged in.

A successful CSRF attack can be devastating for both the business and the user. It can result in damaged client relationships, unauthorized fund transfers, changed passwords, and data hold up including taken session cookies.

CSRFs are typically conducted using malicious social engineering, such as an email or link that tricks the victim into sending a forged request to a server. As the unsuspecting user is authenticated by their application at the time of the attack, it’s impossible to distinguish a legitimate request from a forged one.

Low-Severity Vulnerabilities

Low Severity Vulnerabilities include information leakage, configuration error, and need for some security measures. They can be combined with other issues of a higher severity level, and can be used in conjunction with social engineering (manipulating people into following certain actions or revealing crucial information), to cause a more severe impact on the target. In comparison to Critical, High and Medium Severity issues, these findings have limited effect.

The web application vulnerabilities caused due to low severity includes:

Documentation Files
Insufficient Protection
Failure to encrypt sensitive data

Two-Factor authentication can go a long way in preventing these vulnerabilities. Low-Severity flaws are the easiest one to avoid when comparing to high and medium.

The failure to follow the best security practices may be the factor for security vulnerabilities.

The common factor that comprises a website and web application security includes,

Use of Open-Source software components
Wrong choice of software components that comprise the infrastructure of a website or app
Short project time frame.


In short, to secure our web applications from all common vulnerabilities, it's important to have a proper security testing process in place.

This method involves conceptualizing, developing, and deploying a series of minimum viable products on security programs.

Tools are available for the protection of web application security and to scan for vulnerabilities.

If you’re looking to secure your web application from vulnerabilities, Beagle Security can help you to identify vulnerabilities on your website before hackers exploit them. You can sign up for a free account here.

Top comments (0)