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What is a Trojan Horse (Computing)?

In computers, a Trojan horse is software that looks to be innocent but is actually dangerous and is downloaded and installed on a computer. Unexpected changes to computer settings and activity, even when the machine is intended to be turned off, are both symptoms of a Trojan infection.

What is a Trojan Horse in Computing

Figure 1. What is a Trojan Horse in Computing

The Trojan horse is usually disguised as a harmless email attachment or free download. When a user opens an email attachment or downloads free software, the malware contained therein gets downloaded to the user's computer. Once inside, the malicious code may carry out any task the attacker intended.

How Do Trojans Work?

Trojan viruses function by exploiting a user's lack of security awareness as well as computer security measures such as antivirus and antimalware software. A Trojan usually appears as a malicious attachment to an email. The file, software, or application looks to have been downloaded from a reliable source. When the user opens the email attachment, the trustworthy source from which it came might be a deception. The aim is to get the user to open the file and download it.

Malware or other harmful content is then installed and activated on the computer or other devices as a result of this. Malicious material spreading to other files on the device and causing computer harm is a typical type of attack. The manner in which it does this differs from Trojan to Trojan. It's all down to the hackers who created the Trojan malware's design and aim.

A Trojan horse, like the ancient Greek Trojan horse, infects a computer from within. Users may download and activate the Trojan horse on their own, much as Troy was duped into bringing it in as an honored symbol to end the war. The Trojan horse's method of infection is determined by the computer's design. When a Trojan infects a computer, its main purpose may be one of the following.

  • Remove all data from the device.
  • Copies of data are made to be stolen and sold or to be used for other malicious reasons.
  • Make changes to the data
  • Data might be blocked or data can be accessed.
  • Disrupt the target computer's and/or network's performance.

Is Trojan a Virus or Malware?

If you look for Trojans online, you'll see that the term "trojan virus" is frequently used. While such a word is often used, it is strictly inaccurate. Both Trojans and computer viruses are kinds of malware, yet they have distinct characteristics. The primary distinction between viruses and Trojans is that viruses multiply themselves, whereas Trojans do not. A virus can spread to other devices by generating copies of itself and attaching them to the infected machine's software, folders, and files. When a Trojan infects a device, on the other hand, it remains there until the user transfers or downloads the dangerous application to another machine.

What are the Types of Trojan Malware?

Trojans are classified in computers depending on their capabilities. It all depends on the Trojan's harmful payload or malicious code. When a Trojan infiltrates a device, its payload performs actions that fall into one of the following categories:

1. Backdoor Trojans

A backdoor Trojan computer virus is a type of malicious software that infiltrates a victim's computer without the owner's knowledge or consent. Once one of these viruses has been installed on a victim's computer, it may be viewed and controlled remotely. This puts all data on the computer in jeopardy, as well as anyone who enters personal information onto the computer.

2. DDoS Trojans

The purpose of DDoS Trojans is to perform denial-of-service attacks against the victim's IP address. During such attacks, numerous compromised devices send a stream of requests to the DDoS target, overwhelming it and forcing it to cease working. Cybercriminals need to infect a large number of machines with DDoS Trojans to launch a successful DDoS attack. This is frequently accomplished through mass spam and phishing. When a botnet is ready, all infected machines attack the victim at the same time.

3. Banking Trojans

Banker Trojan is a sort of malware software that is meant to steal financial information from you, such as online banking, e-payment systems, and credit or debit cards. The stolen information is then sent to the Trojan's malevolent user through email, FTP, the web, or other ways. Until it is installed on the computer, it might appear to be a legitimate piece of software. The Trojan horse can then acquire access to a computer system and steal vital data and information once it has been installed.

4. Dropper or Downloader Trojans

Droppers are the initial stage of a blended attack, which is a three-part malware bundle that includes a dropper, loader, and further software (often a rootkit). The dropper infects your device and sets the stage for the loader to install a rootkit on it and give a hacker access. Other forms of malware will be installed via downloader Trojans.

5. Fake Antivirus Trojans

Antivirus software that is fake Trojans is very cunning. Instead of safeguarding, they cause major problems for every device. They want to create fear among naive users by claiming to have discovered a virus and encourage them to pay a price for efficient protection. Instead of a useful virus scanner, the user is left with even more issues, since their payment information is sent to the Trojan's creator for further exploitation. So, if your browser pops up with a malware alert when you visit a website, disregard it and solely trust your system's virus scanner.

6. Infostealer Trojans

A Trojan Horse Infostealer, often known as the information thief, is a malicious computer Trojan created by digital hackers and programmers to acquire and steal important data from susceptible systems without the users' awareness. The most prevalent InfoStealer Trojan strain captures the following data:

  • Name of the user
  • Passwords
  • Device IDs
  • Online banking credentials
  • Postal codes
  • Phone numbers
  • Regions
  • Security Certificates

The Infostealer Trojan may also discreetly monitor user activity and record conversations with online banking services and social media, allowing it to steal crucial data packages. Cybercriminals frequently capture important data and files from users and then transfer the information to a distant server, where they may later utilize it to carry out their criminal operations.

7. Ransomware Trojans

Ransomware Trojan can alter data on your computer, causing it to malfunction or prevent you from accessing certain information. The offender will only unblock your data or restore your computer's functionality once you have paid the ransom demanded.

8. SMS Trojans

They may appear to be relics from a previous century, yet they are still active and constitute a serious threat. SMS Trojans, like the Android virus Faketoken, may operate in a variety of ways. Faketoken, for example, sends bulk SMS messages to costly overseas lines while masquerading as a typical SMS app in the system. The costs must be covered by the smartphone owner. Other SMS Trojans set up connections with costly premium SMS services.

9. Mailfinder Trojans

This form of malicious software harvests email addresses from a computer and sends them to the malicious user via email, the web, FTP, or other ways. Cyber crooks then exploit stolen addresses to send viruses and spam to large groups of people.

10. Instant Message Trojans

Trojan-IM malware steals your passwords and login information for instant messaging services like AOL Instant Messenger, ICQ, Yahoo Pager, Skype, MSN Messenger, and others. It may be argued that these messengers are no longer in use. Even new communication services, however, are vulnerable to Trojans. Trojans might potentially attack WhatsApp, Facebook Messenger, Signal, or Telegram. A Windows Trojan was conscripted via a Telegram channel as recently as December 2020. In addition, phishing attacks on instant messaging should be avoided.

11. Exploit Trojans

Exploits are software that contains information or code that takes advantage of vulnerabilities in a computer application. These Trojans inject code onto a machine that is specifically tailored to exploit a flaw in a certain piece of software.

12. Rootkit Trojan

Rootkits are programs that are meant to hide particular items or actions in your computer. Their primary goal is to keep malicious programs from being noticed, hence extending the time that they may execute on an infected machine.

What is the Difference Between Spyware and Trojan?

Spyware is a sort of software that performs tasks such as observing and tracking user behaviors as well as gathering personal information. Spyware programs, in general, install themselves on a computer and make money for a third party by gathering data from the user without his permission. By operating in the background, malicious spyware tries to capture passwords and personal information from users.

On the other hand, Trojan Horse is a form of malware that utilizes misleading and fictitious names to deceive users about its actual intentions and then executes them. Trojan Horses are malicious programs that masquerade as genuine and beneficial software yet allow hackers to gain unauthorized access to and control of a computer system. Below you can find 5 differences between spyware and trojan.

  • Spyware is not as dangerous as a Trojan horse. The Trojan horse is a more dangerous threat than spyware.
  • Spyware has been set up for commercial use. Trojan Horse has been put in place for malicious intentions.
  • Spyware makes money for a third party by gathering user data without his consent. Trojan Horse can offer hackers unauthorized access and control of the system.
  • The spyware's main goal is to keep track of the system's activities. The trojan horse's main goal is to keep the system's activities under control.
  • Antivirus software is unable to identify spyware but can identify Trojan horses.

How to Prevent Trojan Horse Attacks?

To protect against Trojan attacks, use a combination of solid network security measures and a Trojan scanner frequently. Keep these tips in mind if you want to protect yourself and your system from being attacked.

  • Never download or install any product software from a site or source that you don't entirely trust.
  • Avoid being a victim of phishing scams: Do not open or snap a connection in an email that was sent to you by a random person.
  • Update your operating system and any security protocols that have been implemented: Update your operating system regularly to guarantee that your product is becoming more capable of combating threats. Security fixes for the most recent threats are usually included in updates.
  • Do not go to any risky places: Keep an eye out for sites that don't have security certificates - their URLs should begin with HTTPS:// rather than HTTP://. The S stands for secure, and a lock should appear next to the URL in the location bar.
  • Clicking spring up or flagging from the web is not a good idea: New, untrusted popups should not be clicked since they might contain terrifying Trojan horses.
  • Passwords that are confusing and fascinating are used to protect records. A solid secret key is simple to decipher and is indisputably made up of a mix of upper- and lower-case letters, special characters, and digits. Try not to use the same secret phrase in every situation and change your secret key on a regular basis. A password manager program is an excellent way to keep track of your passwords.
  • Firewalls will keep your data safe. Firewalls filter the data that enters your device from the internet. While most operating systems come with a built-in firewall, it's also a good idea to use an equipment firewall for total protection.
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  • Consistently back up. While backing up your data will not prevent you from installing a Trojan, it will assist you if you lose anything important due to a malicious attack.

How Trojans Impact Mobile Devices?

Trojans aren't just a concern for laptops and desktops. They can also have an effect on your mobile devices, such as phones and tablets. In general, a Trojan is connected to software that appears to be legitimate. In truth, it's a malware-infected phony version of the software. Unsuspecting consumers can frequently obtain them via unapproved and pirate app shops run by cybercriminals. These applications can also collect information from your smartphone and send premium SMS texts to make income. One type of Trojan software has been designed particularly for Android smartphones. It's known as Switcher Trojan, and it infects users' devices to target their wireless networks' routers. What's the end result? Cybercriminals might reroute communications through Wi-Fi-enabled devices and exploit them to perform a variety of crimes.

How to Remove Trojan Malware?

Using professional Trojan removal software is the best technique to remove a Trojan infection from any device. Trojans are removed in the same way that viruses and other malware are removed from your computer.

  1. Install antivirus software from a reputable source.
  2. Switch to Safe Mode.
  3. To prevent malware from operating or accessing the internet, restart your PC in Safe Mode.
  4. Temporary files should be deleted.
  5. Use the Disk Cleanup program to delete temporary files. This will expedite the malware scan that follows.
  6. Check your computer for malware.
  7. Scan your computer for Trojans and other infections with your antivirus software. The infection should be detected and removed automatically by your program.
  8. Recover data or files that have been damaged.
  9. If you've been routinely backing up your computer, use the backup to recover any damaged files or data.

What are Examples of Trojan Horse Attacks?

Some of the most well-known cyberattacks in history have been triggered by Trojan horse software. A look at some of the most well-known Trojans follows.

  1. Emotet: Emotet was first discovered in 2014 as a financial Trojan. Emotet gained headlines in the cybersecurity world as thieves began exploiting it to deliver other malware instead. Emotet was widely regarded as one of the most dangerous malware strains ever generated, and it used enormous spam and phishing efforts to target both corporate and individual victims. The virus was used to construct many botnets, which were then rented out to other adventurous cyber criminals on a malware-as-a-service (MaaS) basis. In 2021, Emotet was eventually brought down by a concerted international law enforcement operation.
  1. ZeuS: In 2007, the ZeuS Trojan made its debut in a data theft attack against the US Department of Transportation. ZeuS is primarily known as a banking Trojan, and it is widely used to steal financial data via two browser-based methods:
  • Keylogging: As you type information into your browser, the Trojan logs your keystrokes.
  • Form grabbing: When you log in to a website, ZeuS can intercept your login and password. ZeuS infected millions of machines thanks to phishing emails and automated drive-by downloads on infected websites, which is why it was utilized to construct Gameover ZeuS, one of the most notorious botnets of all time.
  1. Shedun: Shedun is an Android adware Trojan horse that repackages real Android apps with fraudulent adware before rehosting them on third-party download platforms. When you download an app from one of these sites, you'll also acquire adware. When you install the infected program, you'll be bombarded with adverts that the attacker uses to make money. It is extremely difficult to remove viruses from an Android handset, and most sufferers have chosen to purchase new devices instead. Shedun was said to have infected over 10 million Android smartphones by 2016.

History of the Trojan Horse

The Trojan horse is a mythological figure from Greek mythology. Legend has it that the Greeks created a giant wooden horse that the inhabitants of Troy used to enter the city. Men hiding within the horse emerged during the night, unlocked the city's doors to let their troops in, and overran the city.

The phrase was originally used in a 1974 paper by the United States Air Force over "vulnerability in computer systems". Ken Thompson made it famous when he got the Turing Award from the Association for Computing Machinery (ACM) in 1983. The Turing Award is granted by the Association for Computing Machinery (ACM) to an individual of technical significance in the computer field.

A growth in bulletin board systems (BBS) throughout the 1980s led to the rapid proliferation of Trojan horse attacks. A BBS was a computer system that ran software that allowed users to hack into it over the phone line. After logging into the BBS, a user might do tasks such as uploading, downloading, and distributing possibly dangerous material.

The pest trap or Spy Sheriff was the name given to the first Trojan horse virus. This early Trojan horse was able to infect over one million computers all across the world. It appears as a slew of pop-up adverts, most of which appear to be warnings, informing users of the need for an esoteric software package. It is incredibly tough to uninstall the Spy Sheriff Trojan horse after it has been successfully installed on a machine. Spy Sheriff is typically undetectable by antivirus and antimalware software, and it cannot be removed with a system restoration. Furthermore, if a user attempts to remove the Spy Sheriff program, the Trojan horse reinstalls itself on the machine utilizing hidden infected files.

A guy was arrested in October 2002 after 172 photos of child pornography were discovered on his computer's hard disk. The court took almost a year to acquit him of the accusations and accept his explanation that the data were downloaded without his knowledge by a Trojan horse. This is one of the earliest instances where the Trojan horse defense worked.