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What is a Website Vulnerability and How Can it be Exploited?

A website vulnerability is a weak point or misconfiguration in the code of a website or web application that allows an attacker to gain some level of control over the website and possibly the hosting server.

Most vulnerabilities are exploited through automated means such as vulnerability scanners and botnets. Cybercriminals develop specialized tools that scan the internet for specific WordPress or Joomla, looking for widespread and publicized vulnerabilities.

Once found, these vulnerabilities are exploited to steal data, distribute malicious content or inject defacing and spam content into the vulnerable website.

Types Of Website Vulnerabilities

There are five common types of vulnerabilities in websites that attackers often exploit. While this is not an exhaustive list of all possible vulnerabilities a determined attacker can find in an application, it does include several of the most common vulnerabilities that websites have today.

1. SQL Injection Vulnerabilities (SQLi)

SQL injection vulnerabilities describe areas in website code where direct user input is passed to a database. Malicious people use these forms to inject malicious code, also called payload, into a website’s database. In this way, the cybercriminal can access the website in several ways, for example, by

  • Injecting malicious/spam posts on a website
  • Stealing customer information
  • Bypassing authentication to gain complete control of the website.

Due to its versatility, SQL Injection is one of the most commonly exploited website vulnerabilities. It is commonly used to access open source content management system (CMS) applications such as Joomla!, WordPress and Drupal.

SQL injection attacks, for example, have even been linked to a break-in at the U.S. Election Assistance Commission and a popular Grand Theft Auto video game forum, resulting in the exposure of user data.

2. Cross-Site Scripting (XSS)

Cross-Site Scripting is when attackers inject scripts via uncontrolled user input or other fields on a website to execute code. With Cross-Site Scripting, it is not the website or server itself that is attacked but the visitors to the website.

This often means that attackers inject JavaScript into the website to execute the script in the visitor’s browser. Browsers are unable to recognize whether the script should be part of the website or not, leading to malicious actions such as

  • Session hijacking
  • Distribution of spam content to unsuspecting visitors
  • Stealing session data

Some of the most extensive attacks on WordPress stem from Cross-Site Scripting vulnerabilities. However, XSS is not limited to open-source applications. Recently, a Cross-Site Scripting (XSS) vulnerability was discovered in the system of gaming giant Steam, potentially allowing attackers to expose login credentials.

3. Command Injection

Command injection vulnerabilities allow attackers to remotely inject and execute code on the website’s hosting server. This happens when user input passed to the server, such as header information, is not validated correctly, allowing attackers to inject shell commands into the user information.

Command injection attacks are particularly critical since they can allow malicious actors to initiate the following

  • Hijack an entire website
  • Hijack an entire hosting server
  • Use the hijacked server for botnet attacks

One of the most harmful and widespread Command Injection Vulnerabilities as the Shellshock vulnerability, which affected most Linux distributions.

4. File Inclusion (LFI/RFI)

Remote file inclusion (RFI) attacks utilize the include functions in server-side web application languages such as PHP to perform code from remotely stored data.

Attackers host malicious files and then use insufficiently sanitized user input to inject or modify an include function in the PHP code of the victim site. Can then use this include to initiate the following:

  • Submitting malicious payloads that can use to include attack and phishing pages in visitors’ browsers.
  • Embedding malicious shell files into publicly accessible websites
  • Taking control of a website administration panel or host server

Local file inclusion (LFI), like remote file inclusion, can occur when user input can change the entire or absolute path to included files. Attackers can, after that, use this vector to gain read or write access to sensitive local files, such as configuration files having database credentials.

The attacker could also perform a directory traversal attack by changing the path of an included file to view the backend and host server files to expose sensitive data

A local file inclusion attack can become a remote file inclusion attack if, for example, the attacker can include log files that have previously been injected with malicious code through public interaction.

These types of vulnerabilities are often used for other attacks such as DDoS and Cross-Site Scripting attacks. They have also been used to expose and steal sensitive financial information, such as Starbucks, which was the victim of an embedding attack that compromised customers’ credit card data.

5. Cross-Site Request Forgery (CSRF)

Cross-site request forgery attacks are much less common but can be very dangerous. CSRF attacks entice website users or administrators to perform malicious actions for the attacker unknowingly. As a result, attackers can perform the following actions with valid user input

  • Change order values and product prices
  • Transfer funds from one account to other
  • Change user passwords to hijack accounts.

These types of attacks are particularly vexing for e-commerce and banking websites, where attackers can gain access to sensitive financial data. Recently, used a CSRF attack to take control of the DNS settings of a Brazilian bank for more than five hours.

Mitigating and Preventing Vulnerabilities

You can take simple steps to mitigate vulnerabilities and prevent hackers from gaining unauthorized access to your website.

Update your applications

The first important step in securing your website is to ensure that all applications and their associated plugins are up to date. Vendors often release mandatory security patches for their applications, and it is essential to make these updates on time.

Malicious actors keep up with news about open source applications and have been known to use update notifications as a template for finding vulnerable websites. Signing up for automatic application updates and email notifications of critical patches will keep you one step ahead of the attackers.

Use a web application Firewall (WAF)

Web app firewalls are the first line of defense against those who scan your website for vulnerabilities. web application Firewalls prevent malicious traffic from accessing your website in the first place. This includes blocking bots, known spam or attack IP addresses, automated scanners, and attack-based user input.

Malware Scanner

Your last line of defense is to use a reputable automatic Malware Scanner. It is recommended to find one that automatically detects vulnerabilities and removes known malware.

Advanced programmers may choose to manually check their code and implement PHP filters to clean up user input. This includes restricting image upload forms to .jpg or .gif files and safe listing forms to allow only expected input.

Knowing the types of vulnerabilities hackers might exploit your web applications is an essential first step in securing your website. Vulnerabilities can be fatal not only to your website and server but also to your customers’ data.

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