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Trojan Horse

What is a Trojan Horse?

Trojan horse is one of the most dangerous categories of malware. Trojans are created with the intention of taking over control of computers and allowing the hackers to spy on the users. They are otherwise known as RAT (remote access tool/trojan) and trojan horse viruses.

Over the years we have seen many different types of them – developed by both amateur programmers and highly experienced criminal collectives. This has resulted in complex attacks with a lot of Trojans that are targeted against both end users and companies.

By definition, a malware is categorised as a Trojan horse if it fulfils the main role – to infect a computer and allow hackers to take over control of the victim machines. This can be done by hooking up to system processes and manipulating them for access or via other common weaknesses in the user-installed applications or operating system as a whole.

Trojan horses have grown to be much more than simple spy tools, they may contain advanced functionality or be used to infect the computers with other malware. This is particularly useful when the Trojan has been configured to “prepare” the environment. Most recent examples of this category are well-known for making sure that modifications to the operating system have been made in order for the Trojan to run without interruption from it or security applications that might be installed.

Related: Astaroth Trojan Uses YouTube Channels to Hide Command and Control Servers

How Does a Trojan Horse Infect Computers?

There are several major infection methods that are used by hackers to install Trojans. An important factor to consider is that the deployment can take place via a several-stage delivery process. This is often done by using several mechanisms following a sequence of prescribed events.

A common strategy is to deploy small-sized scripts which will retrieve a second “stage”. It is often placed in a archived format or encrypted form. The script will unpack and place the files in system folders and other locations where it might not be scanned by anti-virus engines and other security services.

Trojans and related files can be uploaded to hacker-controlled sites or other places where a lot of users might search for data. Common sources may include any of the following:

  • Social Networks — The Trojan files can be posted on profiles, groups, chat rooms and pages. They can be of hacker-controlled profiles or hacked ones.
  • Web Portals and Landing Pages — The criminals can create landing pages, portals and fake search engines. This is especially useful when redirects scripts are implemented. When the users navigate to different elements of the pages the files can be downloaded by either clicking on links or interacting with content: scripts, pop-ups, banner and ads.
  • File-Sharing Networks — Trojan files can be easily uploaded either by themselves or in infected data to networks like BitTorrent and other software used to distribute files. They are a very popular outlet for spreading both pirate and legitimate files.
  • Shortened URLs — The hackers can easily include links leading to the Trojan horse infections in shortened addresses. They might use popular services to “mask” the exit URL address.

Many Trojan infections, however, happen when a carrier file is run by the end users. They have a much higher chance of infection as the users are much more likely to run them instead of standalone archives or executable files. Examples of such payload carriers can be macro-infected documents which can be of all popular file formats: presentations, text documents, databases and spreadsheets. When they are opened by the victims a prompt will be generated which will ask them to enable the built-in macros, the most popular reason which is quoted is that this is required in order to view the contents. The alternative is to create malicious application installers of popular software. This is done by taking the original versions from their official sources and adding in the necessary code.

Otherwise Trojan infections can be done by using direct attacks. They are coordinated and executed using hacker toolkits and complicated suites and can take be used against whole networks. The easiest way is to look for security weaknesses in the computers which can exploit to a Trojan installation.

The criminals will target unpatched software or badly configured ones — these are the easiest way to break into a given computer. Other campaigns can make use of brute force attacks wherein the credentials to certain services can be calculated and trialed to gain entry. The hackers may either use ready-made password list files or use an algorithm to generate them.

Among the easiest ways to deploy Trojans is to command previously installed malware to retrieve them. This is commonly done when ransomware viruses are considered, some of the well-known families are deliberately programmed to do so after the encryption phase has started working. This is done in order to monitor if the victims are going to pay the ransom decryption fee.

What Happens After Trojan Horse Infects My Computer?

Trojan horse infections are primarily developed to take over the target computer devices however this is only the original dictionary definition. Nowadays Trojans are among the most complicated and damaging types of malware infections. While they have the main goal of remote controlling computers there are many other malicious actions that can be undertaken by it.

What Was Hidden Inside Trojan Hours

Commonly Trojans are designed with a modular codebase allowing them to start various components that can be built into them or downloaded and run when the hackers instruct them to do so. Depending on the way the virus is designed this can also happen automatically if the engine deems that the infected machine conforms to certain conditions. Typical Trojan virus activity can include the following:

  • Information Retrieval — The main engine can launch a data gathering command which may collect information that can be personally identifiable information or a report of the installed machine components. This is often done to generate an unique ID signature for each computer allowing the hackers to easily keep track of the number of infected devices. The gathering of such information may also be used for other crimes such as identity theft and financial abuse.
  • System Boot Options Changes — The Trojan can be programmed to manipulate the boot options and automatically start the malware when the computer is powered on. This can also prevent the users from accessing recovery menus. This can seriously hinder manual user recover methods.
  • System Configuration Manipulation — Trojans can edit the configuration of important system files and user settings. Depending on what exactly has been altered this can lead to data loss, unexpected errors and serious performance issues.
  • Persistent Installation — Malware of this category are often programmed to scan the infected systems for any installed security software. If they are detected then their engines can be disabled or entirely removed. This can act against the likes of virtual machine hosts, anti-virus programs, sandbox environments, firewalls and intrusion detection systems.

Trojans will typically operate by creating and maintaining a connection to a hacker-controlled server, at this point the hackers will be able to run the prescribed commands. Data can be transferred from the infected computers — not only individual files, but also supplementary data. Examples can be web browser information — it can be harvested for stored history, cookies and account passwords. Information can also be retrieved from the clipboard, some Trojans may also include keylogger functionality — the ability to monitor and record mouse movement and keyboard input.

How to Protect My Computer from Trojan Horse?

To a large extent there are numerous ways through which users can prevent some of the simpler Trojan viruses from their computers. This will work in cases where the Trojan horse viruses are delivered to the users via sites and email messages. Users should know that the majority of attacks are delivered via phishing tactics — the target victims will be scammed by the users to interact with email messages, clicking on sites and links or entering data in fields. Website phishing is very popular among all levels of experience — the simplest sites are merely badly made copies of commonly used services and company pages. More sophisticated ones can be hosted on almost the same sounding domains, incorporate security certificates and replicate the design and structure. To avoid being scamed always inspect the link URLs and make sure that they point exactly to the official and legitimate domain used by a given service. It is very easy for hackers to replace o’s with 0’s as some browsers and display resolutions might not clearly show the difference.

When it comes to email messages never open links and attachments that have been sent by unknown and untrusted people, companies or services. Also make sure to enable the file extensions view in your operating system to prevent the execution of double extensions. Phishing email messages can send out such files – they are usually of popular documents or archives. When they are placed on the system the double extension will hide executable code or other malware techniques.

Other general-purpose tips to prevent Trojan horse infection scenarios are the following:

  • Avoid Accepting Invites From Unknown People on Social Network – Generally hackers can automatically generate profiles that include all basic account necessities. They can be programmed to automatically send out Trojan-infected files.
  • Rely on Official Download Sources Only — Many Trojan data can be embedded in software patches, updates and add-ons which can be easily uploaded to fake portals and popular web communities. The hackers will likely use hacked or specially created profiles for this purpose.
  • Always Use A Reliable Security Suite — Having a simple anti-virus software nowadays is not enough. While definition updates and software stability is important there are a lot of threats that may still infect target users of different categories. This is the reason why we always recommend to use a specialized anti-malware solution in combination with anti-virus programs. This combination will ensure that a proper recovery following a security incident can be done.
  • Use Operating System Security Features When In Need — Trojan attacks can spread through the network, this is the reason why operating system developers have placed some basic network defense settings. They can be enabled by the users using the Settings menu and can vary from version to version. One of the most important example is the Work profile, a function which is used when laptop users are connecting their devices to Public or Work Wi-Fi networks. In this case network sharing will be switched off which will limit the infection potential of Trojans that have implemented a worm-like propagation.

The top advice to follow is to always be on guard! Trojan virus infections are among the most advances and computer criminals are constantly devising new infection tactics. Keep yourself updated on new malware, being informed is the best protection.

Martin Beltov

Martin graduated with a degree in Publishing from Sofia University. As a cyber security enthusiast he enjoys writing about the latest threats and mechanisms of intrusion.

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Preparation before removing Trojan Horse.

Before starting the actual removal process, we recommend that you do the following preparation steps.

  • Make sure you have these instructions always open and in front of your eyes.
  • Do a backup of all of your files, even if they could be damaged. You should back up your data with a cloud backup solution and insure your files against any type of loss, even from the most severe threats.
  • Be patient as this could take a while.
  • Scan for Malware
  • Fix Registries
  • Remove Virus Files

Step 1: Scan for Trojan Horse with SpyHunter Anti-Malware Tool

1. Click on the "Download" button to proceed to SpyHunter's download page.

It is recommended to run a scan before purchasing the full version of the software to make sure that the current version of the malware can be detected by SpyHunter. Click on the corresponding links to check SpyHunter's EULA, Privacy Policy and Threat Assessment Criteria.

2. After you have installed SpyHunter, wait for it to update automatically.

SpyHunter 5 Scan Step 1

3. After the update process has finished, click on the 'Malware/PC Scan' tab. A new window will appear. Click on 'Start Scan'.

SpyHunter 5 Scan Step 2

4. After SpyHunter has finished scanning your PC for any files of the associated threat and found them, you can try to get them removed automatically and permanently by clicking on the 'Next' button.

SpyHunter 5 Scan Step 3

If any threats have been removed, it is highly recommended to restart your PC.

Step 2: Clean any registries, created by Trojan Horse on your computer.

The usually targeted registries of Windows machines are the following:

  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce

You can access them by opening the Windows registry editor and deleting any values, created by Trojan Horse there. This can happen by following the steps underneath:

1. Open the Run Window again, type "regedit" and click OK.
Remove Virus Trojan Step 6

2. When you open it, you can freely navigate to the Run and RunOnce keys, whose locations are shown above.
Remove Virus Trojan Step 7

3. You can remove the value of the virus by right-clicking on it and removing it.
Remove Virus Trojan Step 8 Tip: To find a virus-created value, you can right-click on it and click "Modify" to see which file it is set to run. If this is the virus file location, remove the value.

Step 3: Find virus files created by Trojan Horse on your PC.

1.For Windows 8, 8.1 and 10.

For Newer Windows Operating Systems

1: On your keyboard press + R and write explorer.exe in the Run text box and then click on the Ok button.

Remove Virus Trojan Step 9

2: Click on your PC from the quick access bar. This is usually an icon with a monitor and its name is either “My Computer”, “My PC” or “This PC” or whatever you have named it.

Remove Virus Trojan Step 10

3: Navigate to the search box in the top-right of your PC's screen and type “fileextension:” and after which type the file extension. If you are looking for malicious executables, an example may be "fileextension:exe". After doing that, leave a space and type the file name you believe the malware has created. Here is how it may appear if your file has been found:

file extension malicious

N.B. We recommend to wait for the green loading bar in the navigation box to fill up in case the PC is looking for the file and hasn't found it yet.

2.For Windows XP, Vista, and 7.

For Older Windows Operating Systems

In older Windows OS's the conventional approach should be the effective one:

1: Click on the Start Menu icon (usually on your bottom-left) and then choose the Search preference.

Remove Virus Trojan

2: After the search window appears, choose More Advanced Options from the search assistant box. Another way is by clicking on All Files and Folders.

Remove Virus Trojan Step 11

3: After that type the name of the file you are looking for and click on the Search button. This might take some time after which results will appear. If you have found the malicious file, you may copy or open its location by right-clicking on it.

Now you should be able to discover any file on Windows as long as it is on your hard drive and is not concealed via special software.

Trojan Horse FAQ

What Does Trojan Horse Trojan Do?

The Trojan Horse Trojan is a malicious computer program designed to disrupt, damage, or gain unauthorized access to a computer system.

It can be used to steal sensitive data, gain control over a system, or launch other malicious activities.

Can Trojans Steal Passwords?

Yes, Trojans, like Trojan Horse, can steal passwords. These malicious programs are designed to gain access to a user's computer, spy on victims and steal sensitive information such as banking details and passwords.

Can Trojan Horse Trojan Hide Itself?

Yes, it can. A Trojan can use various techniques to mask itself, including rootkits, encryption, and obfuscation, to hide from security scanners and evade detection.

Can a Trojan be Removed by Factory Reset?

Yes, a Trojan can be removed by factory resetting your device. This is because it will restore the device to its original state, eliminating any malicious software that may have been installed. Bear in mind, that there are more sophisticated Trojans, that leave backdoors and reinfect even after factory reset.

Can Trojan Horse Trojan Infect WiFi?

Yes, it is possible for a Trojan to infect WiFi networks. When a user connects to the infected network, the Trojan can spread to other connected devices and can access sensitive information on the network.

Can Trojans Be Deleted?

Yes, Trojans can be deleted. This is typically done by running a powerful anti-virus or anti-malware program that is designed to detect and remove malicious files. In some cases, manual deletion of the Trojan may also be necessary.

Can Trojans Steal Files?

Yes, Trojans can steal files if they are installed on a computer. This is done by allowing the malware author or user to gain access to the computer and then steal the files stored on it.

Which Anti-Malware Can Remove Trojans?

Anti-malware programs such as SpyHunter are capable of scanning for and removing Trojans from your computer. It is important to keep your anti-malware up to date and regularly scan your system for any malicious software.

Can Trojans Infect USB?

Yes, Trojans can infect USB devices. USB Trojans typically spread through malicious files downloaded from the internet or shared via email, allowing the hacker to gain access to a user's confidential data.

About the Trojan Horse Research

The content we publish on SensorsTechForum.com, this Trojan Horse how-to removal guide included, is the outcome of extensive research, hard work and our team’s devotion to help you remove the specific trojan problem.

How did we conduct the research on Trojan Horse?

Please note that our research is based on an independent investigation. We are in contact with independent security researchers, thanks to which we receive daily updates on the latest malware definitions, including the various types of trojans (backdoor, downloader, infostealer, ransom, etc.)

Furthermore, the research behind the Trojan Horse threat is backed with VirusTotal.

To better understand the threat posed by trojans, please refer to the following articles which provide knowledgeable details.

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