Trojan Horse Questions
What is a Trojan Horse?
A 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 categorized as a Trojan horse if it fulfills 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.
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.
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.
- Guide 1: How to Remove from Windows.
- Guide 2: Get rid of from Mac OS X.
- Guide 3: Remove from Google Chrome.
- Guide 4: Erase from Mozilla Firefox.
- Guide 5: Uninstall from Microsoft Edge.
- Guide 6: Remove from Safari.
- Guide 7: Eliminate from Internet Explorer.
How to Remove from Windows.
Step 1: Boot Your PC In Safe Mode to isolate and remove
Step 2: Uninstall and related software from Windows
Here is a method in few easy steps that should be able to uninstall most programs. No matter if you are using Windows 10, 8, 7, Vista or XP, those steps will get the job done. Dragging the program or its folder to the recycle bin can be a very bad decision. If you do that, bits and pieces of the program are left behind, and that can lead to unstable work of your PC, errors with the file type associations and other unpleasant activities. The proper way to get a program off your computer is to Uninstall it.
Step 3: Clean any registries, created by on your computer.
The usually targeted registries of Windows machines are the following:
You can access them by opening the Windows registry editor and deleting any values, created by there. This can happen by following the steps underneath:
Get rid of from Mac OS X.
Step 1: Uninstall and remove related files and objects
1. Hit the ⇧+⌘+U keys to open Utilities. Another way is to click on “Go” and then click “Utilities”, like the image below shows:
- Go to Finder.
- In the search bar type the name of the app that you want to remove.
- Above the search bar change the two drop down menus to “System Files” and “Are Included” so that you can see all of the files associated with the application you want to remove. Bear in mind that some of the files may not be related to the app so be very careful which files you delete.
- If all of the files are related, hold the ⌘+A buttons to select them and then drive them to “Trash”.
In case you cannot remove via Step 1 above:
In case you cannot find the virus files and objects in your Applications or other places we have shown above, you can manually look for them in the Libraries of your Mac. But before doing this, please read the disclaimer below:
You can repeat the same procedure with the following other Library directories:
Tip: ~ is there on purpose, because it leads to more LaunchAgents.
Step 2: Scan for and remove malware from your Mac
When you are facing problems on your Mac as a result of unwanted scripts, programs and malware, the recommended way of eliminating the threat is by using an anti-malware program. Combo Cleaner offers advanced security features along with other modules that will improve your Mac’s security and protect it in the future.
Remove from Google Chrome.
Step 1: Start Google Chrome and open the drop menu
Step 2: Move the cursor over "Tools" and then from the extended menu choose "Extensions"
Step 3: From the opened "Extensions" menu locate the unwanted extension and click on its "Remove" button.
Step 4: After the extension is removed, restart Google Chrome by closing it from the red "X" button at the top right corner and start it again.
Erase from Mozilla Firefox.
Step 1: Start Mozilla Firefox. Open the menu window
Step 2: Select the "Add-ons" icon from the menu.
Step 3: Select the unwanted extension and click "Remove"
Step 4: After the extension is removed, restart Mozilla Firefox by closing it from the red "X" button at the top right corner and start it again.
Uninstall from Microsoft Edge.
Step 1: Start Edge browser.
Step 2: Open the drop menu by clicking on the icon at the top right corner.
Step 3: From the drop menu select "Extensions".
Step 4: Choose the suspected malicious extension you want to remove and then click on the gear icon.
Step 5: Remove the malicious extension by scrolling down and then clicking on Uninstall.
Remove from Safari.
Step 1: Start the Safari app.
Step 2: After hovering your mouse cursor to the top of the screen, click on the Safari text to open its drop down menu.
Step 3: From the menu, click on "Preferences".
Step 4: After that, select the 'Extensions' Tab.
Step 5: Click once on the extension you want to remove.
Step 6: Click 'Uninstall'.
A pop-up window will appear asking for confirmation to uninstall the extension. Select 'Uninstall' again, and the will be removed.
Eliminate from Internet Explorer.
Step 1: Start Internet Explorer.
Step 2: Click on the gear icon labeled 'Tools' to open the drop menu and select 'Manage Add-ons'
Step 3: In the 'Manage Add-ons' window.
Step 4: Select the extension you want to remove and then click 'Disable'. A pop-up window will appear to inform you that you are about to disable the selected extension, and some more add-ons might be disabled as well. Leave all the boxes checked, and click 'Disable'.
Step 5: After the unwanted extension has been removed, restart Internet Explorer by closing it from the red 'X' button located at the top right corner and start it again.