What Are Trojan Viruses?

One of the most difficult malicious programs for the average computer user to identify. Named for the famed Trojan horse from Greek antiquity, a Trojan virus is designed by hackers to trick users into opening email attachments with malicious code included. The Trojan horse of antiquity seemed harmless, but contained a Greek army inside that sacked the city of Troy after the people brought it in. A Trojan horse virus takes inspiration from this move by tricking users into downloading and executing malicious programs on their computers. The results can be varied and devastating.

What is a Trojan Horse Virus?

Although a Trojan horse virus is referred to using the term virus, it is actually a malicious code or software rather than a virus. A common type of malware, a Trojan resembles a reputable, trusted application or file that convinces the user it is safe to download onto computers or laptops. When the user downloads and executes the malicious software onto a device, the malware contained within is activated. Once the Trojan malware is downloaded and activated, cyber criminals can take control of the device itself, lockout the user with ransomware attacks, or perform whatever malicious threats the designer hand in mind.

How Do Trojan Horses Work?

Trojan viruses work by taking advantage of a lack of security knowledge by the user and security measures on a computer, such as an antivirus and antimalware software program. A Trojan typically appears as a piece of malware attached to an email. The file, program, or application appears to come from a trusted source. As the user views the email attachment, the trusted source it comes from has the potential to be a ruse. The goal is to get the user to download and open the file.

Once this happens, malware or other malicious content is installed and activated on the computer or other devices. One common form of attack is to have malicious content spread to other files on the device and damage the computer. How it goes about doing this varies from one Trojan to the next. It is all in the design and intent of the hackers that built the Trojan malware.

One item to remember when adopting security measures to combat Trojans is the performance of a Trojan. Although the term Trojan virus is often used, Trojans are more accurately described as Trojan malware. A virus is capable of executing and replicating itself on computers and mobile devices. Trojan malware cannot do this. The user has to execute the Trojan and it then goes on to perform the action designed by the hackers behind it.

How Does a Trojan Horse Infect a Computer?

A Trojan horse infects a computer from the inside, much like the ancient Greek’s Trojan horse. Just as Troy was tricked into bringing the horse in thinking it was an honorary symbol to end the war, users download and activate the Trojan horse on their own. How the Trojan horse infects a computer depends on its design. The primary goal of a Trojan horse as it infects a computer is to:

  • Delete data on the device
  • Copy data to steal and sell or use for other nefarious purposes
  • Modify data
  • Block data or access to data
  • Disrupt the performance of the target computer and/or network

Don’t Let Your Employees Accidentally Help A Trojan to Your Data

What Does a Trojan Look Like?

A Trojan horse looks like a reputable file, that is part of what makes it difficult for users to decipher safe from unsafe. Most Trojan files are designed to appear as though the files are coming in an email attachment from a known email address. The malicious content within can unleash worms into a network that cause disruptions in performance and pose threats to data. The files can take the appearance of work files, image attachments, or even links on websites as users surf the web. For example, pop-up windows on other websites or programs available to download on websites. If not trustworthy, the odds are high that these files are malicious in nature

What are the Types of Trojan Horse?

There are numerous different types of malware that threaten computers and other devices in a Trojan attack. Trojan malware takes on various forms and can infect a device from a number of different entry points. The following is a list of the common types of Trojan horse malware, but it should not be considered an all-inclusive list of possible Trojan threats:

  • Backdoor Trojan: these Trojans create a virtual “backdoor” to a computer that allows hackers remote access to the computer. As such, hackers can download user data and easily steal it. Even worse, a backdoor allows a cyber criminal to upload additional malware to the device.
  • DDoS Trojan: known as a Distributed Denial of Service, these types of Trojans take down a network by flooding it with additional traffic it cannot sustain.
  • Downloader Trojan: this type of Trojan targets an already-infected computer to download and install new versions of malicious threats. This includes both Trojans and adware, as examples.
  • Fake AV Trojan: these Trojans behave like antivirus programs or software, but rather than stealing data it seeks to demand money from the user to detect and remove threats. These threats could be real or fake.
  • Game-thief Trojan: this type of Trojan is largely aimed at online gamers and seeks to steal account information that could include credit card information.
  • Infostealer Trojan: this kind of malware does just as the name suggests. It seeks to steal data on infected computers.
  • Malfinder Trojan: the goal of this malware is to steal email addresses accumulated on specific computers and devices.
  • Ransom Trojan: one of the most troublesome Trojans, these threats seek a financial ransom from the user to undo the damage to the computer. It can also block data and impair the performance of the computer.
  • Remote Access Trojan: a remote access Trojan gives the attacker full control over a computer using a remote network connection. There multiples goals for this type of attack that include stealing information or spying on network activity.

What are the Most Common Trojan Infection Points?

One of the most common infection points for Trojan horses, worms, and other forms of malicious content is email. Many users don’t think twice about downloading email attachments when the source email address is trustworthy. This is a factor that hackers take advantage of by hiding malicious codes and programs inside the attachment. However, email is not the only common Trojan infection point.

Most Internet security suites warn users about the compromised nature of particular websites. Visiting a website with a poor security certificate or proceeding after a warning is not advisable as this site is believed to be or known to be the source of Trojan horses. Pop-up windows and suggested download links on these types of sites is also another source of Trojan threats.

How Do You Prevent Trojans?

Knowledge and security measures are the best defense against Trojan horse malware and other malicious content. Internet security software programs can run regular diagnostic scans to check for sites with known malicious content. Updating operating system software when updates are released is important as hackers tend to target holes in outdated systems when launching malware attacks.

Users should focus on protecting accounts with complex, unique passwords for each account. For example, using letters, numbers, and symbols in passwords. Firewalls can also help keep personal information safe. It is also advisable to be cautious with any email attachments and run scans on any email attachment before downloading. Although it won’t prevent a Trojan horse malware attack, it is also advisable to back files up regularly. This will help restore data in the event of Trojan horse threats.

How Do You Remove a Trojan?

If a user discovers a Trojan horse it can be removed using manual operations or software programs. Removing a Trojan can be difficult because it is possible for hidden files to exist on the computer. If a Trojan horse is discovered, the malicious threats can be removed by

  • Identifying the file or files infected and removing it from the system
  • Disable the function of System restore
  • Restart the computer and press F8 (Windows PCs) and select safe mode to start up the computer
  • Use Add or Remove Programs in the control panel to remove the programs affected by the Trojan horse
  • Remove extensions by deleting files of a program within the Windows System folder

While you can follow these manual steps on a personal computer, it is not an effective approach for Trojan viruses that infect enterprise computer systems. In this case, the situation can be very complex and the best approach is to seek outside help. The benefit for any enterprise network using Avatara’s CompleteCloud platform is that its built-in security systems constantly work to prevent Trojan horses and other malware to avoid the problem in the first place.

How Can You Be Sure that Your Computer is Safe?

If worms, malicious codes, and other threats have been downloaded and activated, removal can restore the integrity of the computers involved. However, the user might still wonder if the computer is safe. How does the user know for sure that a computer is safe? Well, for starters, users can exercise greater caution when encountering email attachments or visiting suspicious websites.

Working with a trusted service provider for business networks can also ensure computer systems remain safe. Avatara CompleteCloud has private cloud networks with security that provides users reliable network access and security safeguards that protect that network. These include remote, secure access for users, armed guards with biometric access for users. Server and edge firewalls protect against intrusions, along with intrusion detection software and anti-malware, anti-spam software. We also provide employee cyber security training allowing you to create a human firewall around your data.

Even if users don’t use a private cloud network through Avatara, there are still cyber security measures in place to protect computers and networks. These include features such as DNS filtering, a security operations center with intelligent defense systems, multi-factor authentication for sign-ins, and even encrypted email that can protect against Trojan horse threats through the most common access point. Trojan horse malware poses a serious threat, but there are options available to prevent the negative impacts of worms, Trojan horses, and other types of malware.

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