How command injection attacks work on servers

There are many types of threats that can put our network security at risk. Many varieties of viruses, malware, attacks against servers… In this article we are going to explain how command injection works and how it affects us. It is one more technique that hackers have, but we always have options to make things as difficult as possible and be protected against these types of strategies. The objective is to know the threat to know how it acts and how to avoid it.

What is a command injection attack?

How command injection attacks work on servers

A command injection attack, which is also known as Command Injection , is basically when an attacker injects code to execute commands on a system. It always takes advantage of some existing vulnerability and without the victim being aware of it. In this way they will gain control of the server and be able to use it as if they were a legitimate user.

This technique used by hackers is primarily aimed at compromising servers . For example through a web application or any vulnerability that exists. If there is a program that allows you to execute commands to obtain certain functions, that is where they could inject malicious commands.

Let’s say a server uses a program to perform an action. For example reading documents or collecting usage data. For this it is necessary to execute commands and show us that information. An attacker could perform malicious command injection, whenever there is a bug, and take over that server.

What do they use these attacks for?

After explaining what a command injection attack is, we are going to talk about how they can really affect you. Cybercriminals use these techniques to attack a server and gain illegitimate access, steal data, or even cause it to malfunction.

steal credentials

One of the attacker’s goals when using this method is to steal login credentials. For example, a program that you have installed on the server can be used to collect personal data and even passwords. It is a very common method and is always targeted by hackers.

This can affect both businesses and home users. Whenever we use a vulnerable server, we can suffer attacks of this type that steal our credentials and passwords.

Strain fake programs

Another goal of attackers is to be able to sneak any malicious application into the system. This can be used to control the server, gain access to data or simply install programs that will cause malfunctions or serve as an entry point for other threats and carry out different strategies.

Having fake applications on our computers is one of the main reasons why it starts to malfunction. It happens when we install the programs from unofficial sources, but in this case it is due to hackers injecting malicious commands.

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break the connections

Of course, another problem that command injection can cause is causing server crashes . For example make connections inaccessible via SSH or remote desktop. Ultimately they can gain full control or affect programs that are essential.

If this problem appears, we can say that it is one of the main ones in servers. They are essential equipment to access information and data, for example. If we can’t get in remotely, it means that this team is not going to fulfill its main function.

Change the look of an app

By injecting commands into an application, a cybercriminal can change the appearance of the application. For example, display images at will, modify the menu, the texts… This could lead to data theft, for example if the victim logs in through a menu that redirects him to a fraudulent page.

Furthermore, beyond simply modifying a program, the attacker could render it inoperable or even delete it. It is one more problem that can affect the servers and put their proper functioning at risk.

What to do to avoid these attacks

So what can we do to prevent command injection attacks and our servers from being compromised? As in the case of any other method, it is essential to follow a series of steps to avoid problems and maintain privacy.

These attacks often take advantage of vulnerabilities in the server. Therefore, it is essential to keep everything updated correctly. We must correct any error that appears and always have the latest versions installed so that we do not run the risk of being victims of this problem.

It is also very important to use good encryption . Passwords are the main security barrier and we must use keys that really protect us. They have to be unique and totally random. Ideally, they should contain letters (both uppercase and lowercase), numbers, and other special symbols.

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Another interesting point is to create a white list of users or devices that can access that server and block all others. This will prevent, or at least reduce the possibility, that a cybercriminal can target the server and gain illegitimate control over it. We will prevent you from installing malicious software, blocking connections, etc.

On the other hand, in these cases it is very important to carry out a constant review . We must verify that everything works fine, that nothing strange has appeared in the applications, there are no connections that do not correspond to legitimate users, etc. This will help save time and act as quickly as possible.

Conclusions of this type of threat

We can therefore say that command injection is a major problem affecting servers on the Internet. Hackers can pull off a variety of attacks, with different goals. For example, stealing credentials, sneaking fake programs, making servers stop working…

It is essential to always keep our computers protected, but especially when they are connected to the Internet. We must have all the updates and carry out the necessary changes in the configuration to protect ourselves from this type of attack or any other similar one.