What are Injection Attacks?

You’d agree that the range of different types of cyberattacks is expanding, and the situation is getting intense. Hackers use new and robust techniques to break into systems and steal or modify confidential data. But one creed of cyberattacks are among the oldest and most dangerous: Injection attacks.

Two-thirds of all web app attacks reported in 2019 were attempted using SQL injection attack tactics. So, what is an injection attack anyway? How does it work? And what can you do to prevent and detect it?

Read on for answers to these questions and learn about the various types of injection attacks.


What is an Injection Attack?

Let’s begin by understanding what “injection” means in cybersecurity. Well, an injection attack is when cyberactors inject malicious scripts into a system, web-based application, or platform to intercept crucial data by gaining remote access. 

They can even use this technique to infect a device with malware, compromise backend systems or clients, hijack sessions, and steal data from users linked to a targeted program.

For example, SQL injection attacks(explained in more detail below) occur by exploiting vulnerabilities introduced when developers create dynamic database queries consisting of user-supplied input.


How Do Injection Attacks Work?

In an injection attack, hackers use commands to interfere with backend databases in an unauthorized manner. This is possible because many websites depend on input submitted by users, typically in an HTTPS query run against a database. For instance, users enter their username and password which is then cross-checked with the platform’s database, allowing the user to log in.

So, attackers hijack the process by using the input fields to execute malicious scripts that manipulate normal functions in their favor, overriding a query’s logic. 

Ultimately, any website or application that allows users to upload or enter data may be vulnerable to all kinds of injection cyber attacks. And the consequences are dire—from data loss, theft, and modification to authentication bypass, denial of service, and entire system compromise.

Cybercriminals can even use this technique to infect systems with malware like computer worms to steal users’ personal data and sell it on the black market. So, injection attacks don’t only affect the data integrity of your website but can also put your users’ data in harm’s way.  

Example of an Injection Attack

In 2014, a Russian gang of hackers compiled a list of websites vulnerable to SQL injection attacks and stole 1.2 billion usernames and corresponding passwords. Although there isn’t a precise record of how many accounts or individuals were affected, the incident remains one of the largest of its kind.


What are the Different Types of Injection Attacks?

Any company with a website or user platform must understand cybersecurity risks and vulnerabilities. This includes knowing the following types of injection attacks

SQL Injection (SQLi)

Structured Query Language or SQL is used to communicate with databases to recover, alter, or erase data. In an SQL injection attack, cybercriminals embed malicious SQL statements or commands using web form input fields, comment boxes, pop-ups, etc. to capture, change, or manipulate data.

This type injection attack exploits vulnerabilities in a website’s authorization and authentication processes, which can lead to full system compromise.

Cross-Site Scripting (XSS Injection)

A cross-site scripting attack is possible on web applications allowing user input within the output they generate. Threat actors can then send different end-users corrupted code without validation or encryption. XSS attacks leverage this weakness by injecting malicious script into safe websites. 

Once the end-user visits the targeted site, the script executes and their browser becomes compromised, allowing cybercriminals to steal cookies, monitor web activity, hijack user sessions, and impersonate victims.  

Code Injection

Hackers already know the application code and programming language in a code injection attack. So, they find a vulnerability and exploit it, injecting corrupted scripts to gain access which may contain operating system commands. 

Depending on user privileges, the attacker can access all data, corrupt the entire system, or even infect it with hybrid malware. Code injection exploits typically rely on user-input fields such as text input, HTTP GET/POST/PUT/DELETE parameters, headers, and cookies.

Command Injection

Web applications have to call a system command in certain situations. If user input isn’t validated and restricted, attackers can easily attempt a command injection attack by knowing the operating system used (unlike code injection attacks). 

They typically inject operating system commands via user privileges. Once executed, these types of injection attacks can compromise application infrastructure and elements like connected servers, etc.

Carriage Return and Line Feed Injection (CRLF Injection)

Carriage Return and Line Feed or CRLF are system vulnerabilities that allow malicious actors to inject character sequences. The sequence splits the HTTP response header to write arbitrary contents into the HTTP response body. 

CRLF injection exploits can impact the entire system by incorporating cross-site scripting attack techniques. 

Email Header Injection

Email header injection attacks are similar to CRLF injection attacks. They can occur on any web application that utilizes user input (such as a contact form) to generate and send email messages. 

When this input isn’t validated, cyberattackers can introduce malicious headers, injecting  IMAP/ SMTP commands which tell the mail server to behave differently. While these cyberattacks aren’t directly harmful to the website in question, they’re typically used for spamming and phishing purposes.

Host Header Injection

An HTTP host header attack occurs when a website server trusts a host header without first validating it. Attackers exploit this vulnerability by injecting a malicious payload into the host header to manipulate server-side processes.

As host headers are typically user controllable, cybercriminals can exploit various other vulnerabilities leading to web cache poisoning, SQL injection attacks, and other server-side weaknesses. 

LDAP Injection

The Lightweight Directory Access Protocol or LDAP helps search and manage resources, control user access, and can store login credentials within a network or intranet. 

Cybercriminals inject unvalidated LDAP statements to trick authentication standards, allowing them to gain unauthorized access, steal confidential data, and alter LDAP directory information.


What Vulnerabilities do Injection Attacks Target?

Now that you understand the different types of injection attacks, let’s go over the commonly exploited vulnerabilities. 

These types of cyberattacks target an expansive range of cybersecurity flaws collectively known as injection vulnerabilities. As you’ve seen from the above, there’s usually one common denominator: Unvalidated user input. 

User-input includes anything from comment sections and contact forms that use JavaScript code to database queries, operating system commands, and native application source code.

Basically, any part of a web-based application that lets users enter or upload data is prone to injection attacks.


How to Spot an Injection Attack?

So, what is an injection attack’s telltale signs? These cyberattacks are messy, and mostly rely on trial and error in the early stages—until a hacker finds an exploitable vulnerability. As such, it can be notoriously difficult to spot an injection attack while it’s happening. 

Numerous errors for failed logins or unexecuted SQL queries may indicate an injection attack, along with failed attempts to access invalid objects, stored procedures, or any errors involving permissions.

Of course, it’s much easier and more effective to detect and prevent injection attack vulnerabilities in the first place.

Start by searching the source code for all calls to external sources like exec, and Runtime.exec, XML. etc. Secondly, ensure user-input data is filtered and sanitized before it’s used to generate output data or registered in the application database. 

You must also learn how to recognize malware as SQL injection attacks can infect your devices with viruses, spyware, trojans, etc. This is an indirect way to possibly spot an injection attack.

Another easier way to detect an injection attack weakness is by using an automated web vulnerability scanner which is similar to a pentest tool. It’ll spot attack vectors so that you can stop attackers from entering your system. Alternatively, you can call experts to help you find and patch any injection vulnerabilities in your website or application.


How to Prevent Injection Attacks?

It’s time to learn how to prevent SQL and other injection attacks. The best preventive measure is to code web applications securely. Here are a few more best practices to consider:

  • Use the allowlisting technique for user input validation. It’ll filter bluff and malicious statements and configuration inputs.
  • Developers should use prepared statements with parameterized queries to differentiate between code formats and requested user inputs. 
  • Restrict or limit special characters in input fields. 
  • Remove non-useful elements and functions of a web application to decrease the number of vulnerabilities. 
  • Apply Least Privilege to allow only privileged users to access an account or section of a web application.

Final Thoughts

Injection attacks are a common threat as most applications don’t validate user input. Hackers often exploit misconfigured servers and unpatched vulnerabilities—which can be avoided with the right preventive measures 

It’s better to be safe than sorry; hence companies must use allow listing, the system of least privilege, and secure codes for creating web applications.

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