What Is a Trojan Horse In The Computer Networking?

What is a Trojan Horse Malware?

Unusual behavior on a device, such as unexpected changes to the configuration settings of a computer, is one of the telltale signs that a Trojan virus is currently running on the device.

However, the question “what is Trojan?” can be answered in a straightforward manner by stating that a Trojan is a form of malware that, in most cases, infiltrates a user’s system after being concealed as an attachment in an email or as a file that is available for free download. After being downloaded, the malicious code will carry out the operation that the perpetrator intended it to carry out. This could include gaining backdoor access to business systems, spying on users’ internet activities, or stealing sensitive data. It accomplishes this by reading passwords, logging keystrokes, or opening the door for further malware, which may even take over the entire machine if it gets a chance. These activities might include the following:

• Deleting data
• Blocking data
• Modifying data
• Copying data
• Getting in the way of how computers or computer networks work

Downloads of games, tools, applications, and even software fixes could potentially contain Trojan horses. A great number of Trojan assaults make use of social engineering techniques in addition to phishing and spoofing in order to coerce the target user into doing the desired action.

Trojans can’t make copies of themselves like viruses and worms can.

A Trojan horse and how it works

Before a Trojan horse can infect a computer, the user must download the malicious application’s server side. The Trojan horse can’t just show up on its own. For the attack to be launched on the system, the executable file (.exe file) must be run and the program must be installed. A lot of the time, social engineering is used to get end users to download the malicious application. The download trap could be in a banner ad, a link to a website, or a pop-up ad.

But the most common way for Trojan horses to spread is through emails and attachments that don’t seem dangerous. Spam is a common way for people who make Trojan horses to send their emails to hundreds or thousands of people. As soon as the email is opened and the attachment is downloaded, the Trojan server will be installed and will run automatically every time the computer starts up.

It is also possible for a computer with the Trojan horse to keep sending it to other computers, making a network of computers called a botnet. This is done by turning a normal computer into a “zombie” computer, which means the person who is using it doesn’t know it is being controlled by someone else. Hackers use these zombie computers to keep spreading malware and build a network of zombie computers.

Trojan horse infections can happen on more than just laptops and desktop computers. Mobile malware, which can attack smartphones and tablets, can also be used by Trojans to attack mobile devices. With this kind of infection, an attacker could use these Wi-Fi-connected devices to reroute traffic and commit cybercrimes.

Here’s one way a Trojan horse could be used to harm a personal computer:

The victim gets an email that looks official and has an attachment. When the victim clicks on the attachment, the malicious code is run. Because nothing bad happens and the computer keeps working as usual, the victim doesn’t realize that the attachment is actually a Trojan horse and that his computer is now infected.

The bad code stays hidden until a certain date or until the victim does a certain thing, like going to a banking website. At that time, the trigger turns on the bad code so it can do what it was meant to do. Depending on how the Trojan was made, it may delete itself after it has done what it was supposed to do, go into a dormant state, or keep working.

Examples of Trojan Horse Malware

Here are some of the trojan families that spread quickly and are the most dangerous.

Zeus

Zeus/Zbot is a piece of malware that works in a client/server model, with deployed instances calling home to the Zeus Command and Control (C&C) center. It is thought to have infected more than 3.6 million computers in the US, including machines owned by NASA, Bank of America, and the US Department of Transportation.

Zeus gets on Windows computers and sends private information from the victim’s computer to the Zeus server. It is very good at stealing login information, banking information, and other financial information and sending it to the attackers.

The single C&C server was the weak point of the Zeus system, and law enforcement agencies went after it first. Later versions of Zeus added a domain generation algorithm (GDA), which lets Zbots connect to a list of alternative domain names if the Zeus server isn’t available.

Zeus has many different names, such as:

• Zeus Gameover is a version of the Zeus botnet that is peer-to-peer and doesn’t have a central C&C.
• SpyEye is a program that was made to steal money from online bank accounts.
• Ice IX is a type of financial malware that can take over a browser’s content during a financial transaction and steal login information and other private information from forms.
• Citadel is an open-source version of Zeus that was worked on and improved by a group of cybercriminals. It was replaced by Atmos, which is also an open-source version of Zeus.
• Carberp is a type of financial malware that is one of the most common in Russia. Can take advantage of flaws in operating systems to get root access to target systems.
• Shylock uses a domain generation algorithm (DGA), which is used to get commands from a lot of bad servers.

ILOVEYOU

ILOVEYOU, also known as the “ILOVEYOU virus,” was a trojan that came out in 2000. It was used in the most damaging cyberattack in history, which cost the world $8.7 billion.

The trojan was spread through a phishing email that said, “Please check the attached love letter from me.” The email had an attachment called “ILOVEYOU,” which looked like a text file. Those who were curious enough to open the attachment got infected. The trojan would overwrite files on the computer and then send itself to everyone on their contact list. The virus spread to millions of computers through this simple but effective way to spread.

Cryptolocker

Cryptolocker is a type of ransomware that is often used. It spreads through infected email attachments. A typical message has an infected ZIP file that is password protected, and the password is in the message. The trojan is turned on when the user opens the ZIP file with the password and clicks on the attached PDF. It looks for files to encrypt on local drives and mapped network drives and encrypts them with 1024-bit or 2048-bit keys using asymmetric encryption. The attackers then ask for a ransom in order to give the files back.

Stuxnet

Stuxnet was a Windows Trojan that was made to attack Industrial Control Systems (ICS). It was used to attack Iran’s nuclear facilities, so the story goes. The virus made the operator monitors look like everything was normal, but it changed the speed of the Iranian centrifuges, making them spin too long and too fast and breaking the equipment.

Types of Trojans

Backdoor Trojans

They are a type of Trojan that is easy to make but could be one of the most dangerous. This is because, as a gateway, they can either load all kinds of malware onto your system or make sure your computer is open to attack. Botnets are often set up with the help of a back door. Without you knowing, your computer joins a network of “zombie” computers that are used to attack. Backdoors also make it possible for code and commands to be run on your device or for your web traffic to be watched.

Rootkit

Rootkits are made to hide things or things that are happening on your system. Often, their main goal is to stop malicious programs from being found, so that they can run longer on a computer that has been infected.

Exploit

An exploit is a program with data or code that uses a weakness in an application on your computer to do something bad.

Dropper/downloader Trojans

The Emotet malware is one of the most well-known dropper Trojans. It has been made safe, but unlike a backdoor Trojan, it can’t run any code on the PC itself. Instead, it brings other malware with it, like the banking Trojan Trickbot and the ransomware Ryuk. So, droppers are like downloader Trojans, with the difference that downloader Trojans need a network resource to get malware from the network. Droppers already have the other malicious parts of the program package built into them. Both types of Trojan can be updated remotely and in secret by the programmers who made them, for example so that virus scanners can’t find them with new definitions. This is also a way to add new functions.

Banking Trojans

Banking Trojans are some of the most common viruses. Since more and more people are using online banking and some users aren’t very careful, this makes sense. Online banking is a good way for thieves to get money quickly. Their goal is to get the information they need to get into bank accounts. To do this, they use phishing methods, such as sending the people they think are their victims to a fake page where they are supposed to enter their login information. So, when you use online banking, you should only use secure ways to verify your identity, like the bank’s app, and never enter your access information on a web interface.

| Related Article:

• Phishing e-mail targeting Chase Bank customers

DDoS Trojans

Distributed denial-of-service (DDoS) attacks are still a problem on the Internet. In these attacks, a server or network is flooded with requests, usually by a group of computers called a botnet. For example, in mid-June 2020, Amazon stopped a record attack on its servers. Over the course of three days, 2.3 terabytes of data per second were sent to Amazon’s web services. To get that much computing power, there must be a very large botnet. So to speak, botnets are made up of zombie computers. On the surface, they seem to be running normally, but they are also working in the background to attack. The reason for this is a Trojan with a backdoor that sleeps on the computer without being noticed and can be opened by its operator if needed. If a botnet attack or a DDoS attack works, websites or even whole networks may not be accessible anymore.

Trojan-Ransom

This kind of Trojan can change data on your computer so that it doesn’t work right or you can’t use certain data anymore. The criminal won’t fix your computer or let you access your files until you pay them the ransom money they want.

Fake antivirus Trojans

Fake antivirus Trojans are especially sneaky. Instead of protecting, they cause a lot of trouble for every device. With supposed virus discoveries, they want to scare users who don’t know what’s going on and get them to pay for effective protection. But instead of getting a helpful virus scanner, the user gets more problems because their payment information is sent to the person who made the Trojan so they can use it in other ways. So, if you go to a website and all of a sudden get a virus warning in your browser, you should ignore it and only trust your system’s virus scanner.

Trojan-GameThief

With this kind of program, online gamers’ account information is stolen.

Infostealer Trojan

This type of malware can be used to either install other Trojans or keep the user from finding out that a malicious program is running. The parts of Trojans that steal information can make it hard for antivirus programs to find them when they scan.

Trojan-IM (Instant Messaging)

Trojan-IM programs steal your login information and passwords for instant messaging programs like ICQ, MSN Messenger, AOL Instant Messenger, Yahoo Pager, Skype, etc. One could say that these messengers aren’t used much any more. But Trojans can get into even brand new messenger services. Trojans could also try to get into Facebook Messenger, WhatsApp, Telegram, or Signal. A Trojan for Windows was taken over through a Telegram channel as recently as December 2020. Phishing attacks should also not be able to get through to your instant messaging.

In January 2018, Kaspersky security researchers found a Trojan called Skygofree. The malware has very advanced features. For example, it can connect to Wi-Fi networks even if the user has turned off that feature on their device. The popular messaging service WhatsApp can also be watched by the Skygofree Trojan. It can both read and steal messages.

SMS Trojans

Even though they look like something from another century, they are still around and pose a big threat. SMS Trojans like Faketoken, which is malware for Android, can do different things. Faketoken, for instance, sends a lot of SMS messages to expensive international numbers while pretending to be a normal SMS app. The person who owns the phone has to pay for this. Other SMS Trojans connect to expensive premium SMS services.

Remote access Trojan

This type of malware gives the attacker full control of a user’s computer, just like a backdoor Trojan. The cybercriminal keeps access to the device through a remote network connection, which they use to steal information or spy on a user.

SUNBURST

The SUNBURST trojan virus was released on many SolarWinds Orion Platform. Trojanized versions of a digitally signed SolarWinds file called SolarWinds.Orion.Core.BusinessLayer.dll were used to attack victims. The file that has been hacked is a backdoor. Once it’s on a target computer, it sleeps for two weeks and then gets commands that let it move, run, do reconnaissance, reboot, and stop system services. Communication happens over http to URIs that have already been set.

Trojan-Spy

Trojan-spy programs can watch how you use your computer by, for example, keeping track of what you type on the keyboard, taking screenshots, or getting a list of the programs you have open.

Trojan-Mailfinder

The email addresses on your computer can be taken by these programs.

Mobile Trojans

Most people think of Trojan attacks as things that happen on desktop or laptop computers, but they can also happen on smartphones, tablets, and any other device that can connect to the internet.

Like other malware attacks, mobile Trojan attacks look like real programs, usually an app or something else that people often download. Many of these files come from unofficial, pirated app marketplaces and are made to steal data and files from the device.

Trojan: Malware or Virus?

Some people call a Trojan a Trojan virus or a Trojan horse virus, but these are not correct terms. Trojan malware can’t copy itself or run itself like a virus or worm can. It needs the user to do something specific and on purpose.

Trojans are a type of malware, and like most other types of malware, they are made to damage files, reroute internet traffic, watch what the user does, steal sensitive information, or set up backdoors to the system. Trojans can delete, block, change, leak, or copy data, which can then be sold back to the user for a ransom or on the dark web.

How to recognize a Trojan

Trojan horses often look like normal system files, so it can be hard to find them and get rid of them with regular virus and malware scanners. Most of the time, you need specialized software tools to find and get rid of individual Trojan horses.

But a computer that is infected with a Trojan horse will act in strange ways that can be used to spot it. Some of the odd things could be:

• A change in the computer’s screen, like changing the color or resolution, or a flip that isn’t necessary.
  There are too many pop-up ads that offer solutions to different problems, which might make the user click on the ad.
• The mouse might start moving on its own or stop working at all, and the functions of the mouse buttons might switch places.
• The homepage of the browser might change, or the browser might always send the user to a different website than the one they want. Most of the time, this redirected site will have an offer that users can click on or download to get more malware.
• The computer’s antivirus and antimalware programs will be turned off, and you won’t be able to get to the steps you need to take to get rid of malware.
• Strange messages and graphics may start to show up on the screen.
• In the task manager, you will see programs running that you don’t know.
• The taskbar will either change how it looks or go away completely.
• The background picture on the computer’s desktop can change, as can the way desktop icons and programs are laid out.
• The user’s personal email service may start sending spam messages to all or some of the addresses in the contact list. These messages often contain malware and a convincing way to get the recipient to open and download the attack, which spreads the Trojan horse to other computers.

It’s important to remember that some of the strange things listed above can also be caused by safe, legal software. Also, because of how they are delivered, adware and potentially unwanted programs (PUPs) are sometimes confused with Trojan horses. For example, adware can get on a computer by hiding in a package of other software. But unlike Trojan horses, adware and potentially unwanted programs (PUPs) don’t try to hide once they are on a computer.

How to protect your network from a Trojan horse

The easiest way to avoid a Trojan horse is to never open or download emails or attachments from sources you don’t know. If you delete these messages before opening them, the Trojan horse threat will not happen.

But installing and using an internet security suite is the first step and the key to computer security. Most of the time, the user doesn’t know that a Trojan horse has been installed, so antimalware software must be used to find the bad code, isolate it, and get rid of it. To avoid getting a Trojan horse, users should keep their antivirus and antimalware software up to date and run diagnostic scans on a regular basis.

Other ways to keep a system safe are:

• Changing the software for the operating system (OS) whenever the company that makes the software releases a new version.
• Protecting personal accounts with passwords that are hard to guess and are made up of letters, numbers, and symbols.
• Use caution with all email attachments, even those from known senders, because a Trojan horse could have infected their computer and is using it to spread malware.
• Making regular backups of files so that they are easy to get back if a Trojan horse attack happens.
• Using firewalls to keep all personal information safe.
• Avoiding sketchy and dangerous websites. Sometimes, Internet security software can tell you which sites are safe and which ones you should avoid.
• Only access URLs that begin with HTTPS
• Only install or download programs from publishers you know and trust.
• Choosing not to click on pop-up ads that try to get you to click through to tempting offers and promotions.
• Never open an email if you don’t know what it’s about, who sent it, or who it’s from, or if you have any doubts about it.

Getting rid of a Trojan horse

If a Trojan horse is found on a computer, it should be disconnected from the Internet right away and the suspicious files should be removed using an antivirus or antimalware program or by reinstalling the operating system.

The hardest part of getting rid of a virus is figuring out which files are bad. As soon as the Trojan is found, the rest of the process is easier. The dynamic link library (DLL) error, which is often shown by a computer when there is a Trojan horse, can sometimes help users find the infected files. You can copy this error and search for it online to find out more about the.exe file that is having trouble.

Once the files have been found, System Restore must be turned off. If this function is not turned off, all the malicious files that are deleted will be brought back and the computer will be infected again.

The next step is for users to restart their computers. Users should press the F8 key and choose “safe mode” while the computer is restarting. Once the computer has started up, users should go to the control panel and click on “Add or Remove Programs.” From here, you can remove and delete any infected programs. To make sure that the Trojan application and all of its extensions are gone, all of the program files should be deleted from the system.

Once this is done, you should restart the system again, but this time in the normal way. This should be the end of the process to get rid of the Trojan horse.