Trojan virus. Hero of the occasion of malicious programs

Helga Smith

The majority of users are sure that the viruses are distributed separately. They really believe that you can’t download one trojan virus which would contain 5-7 viruses of completely different types. Yes, such an opinion was actual in 2012…2014, however, it is completely wrong in 2020. Thanks to the technologies development, you can easily download a program declaring that it is capable of, for example, license key generation, but it will also deliver the stealer, miner, keylogger, spyware and backdoor right in your system. It can differ from one case to another, but let’s have it all out first.

History of trojan virus : appearance

First mentions about the programs, who had the functionality that differs from the declared are dated in 19711. Regardless of the absence of malicious functionality in this program, it was named “Trojan Horse” – after the famous horse dummy which was used by Greeks to get into the city of Troy. Greek warriors were hiding under the guise of a wooden horse, left as a gift on the battlefield, and so do the malware inside of the app which is legit at the first sight. 

Despite its early appearance, trojans’ development was not very fast. The main reason is that users had an extremely low level of knowledge about so-called computer hygiene. They were downloading any files from the website they discovered yesterday, paying no attention that there is something wrong with the picture that has the extension of .png.exe. It was very easy to infect the needed amount of users without any tricks, so the trojan viruses were out of demand. However, there were several significant trojans which were used for malware attacks in the 90s.

Trojan virus functioning scheme
Trojan virus functioning scheme

Time will melt it down

With the time flow malware injection came to be not so easy. Computer users became more experienced, antimalware software became widespread, and the operating system (we are talking about Windows) got the capabilities of malware protection. So the malware distributors decided to use a known but low-used thing – trojan virus.

At the beginning of its way one trojan was used to distribute the single type of malware. Such things like trojan-downloader (a type of trojan virus which acts as a downloader for other malware of any type) was not widespread. However, for adware/browser hijacker distribution trojans were still out of demand: people clicked on colourful and blinking advertisements, initiating the downloading of so simple, but annoying viruses; this scheme is actual even these days.

Actual types of trojan virus

Here are description for all types of trojan virus that were developed after the beginning of their active usage, and used even today:

Usually hides under the guise of “password keeper” or “system cleaner”, getting access to your passwords directly or through the cookies. Sometimes can be in its alternate form – keylogger, which steals not your passwords/logins, but all keystrokes.

Tracks all your activities to sell it to someone else. Often used for personalized attacks. Offered as a tracker for your children, spouse or subordinates. Can really offer such functions, but that does not decrease its malicious intent.

Contains a virus that encrypts your data and forces you to pay the ransom for files decryption. Because of the strong encryption algorithm, it is likely impossible to decrypt your files without the specialized software.

Changes your hosts file and then shows you the fake variant of famous websites login pages, like Gmail, Facebook, Twitter and so on, forcing you to input login/password. All information inputted on such websites will be collected by malware creators2.

Remote administration tool for your computer, that is used to add your PC into the botnet or to inject you more malware; creators of these malware usually pay a commission to the backdoor maintainers.

Uses your PC’s hardware capabilities to mine cryptocurrencies. May be easily spotted by a significant plummet of the PC performance.

Facts and stats about trojans in 2020

In the last three years, trojan viruses transformed significantly. Despite distributing every separate type of malware in the separate trojan, trojan virus developers decided to pack several of mentioned types of malware inside of the single trojan. The effect may be reached immediately after the trojan launch (if the malware files are right inside of the trojan program), or after some time (if malicious items are stored on the server). Last type of trojans is called “trojan-downloader”

Trojan viruses statistics
Trojan viruses took over the whole top-10 of the most frequent malware list. Stats from ESET quarterly report.

In combination with ransomware, trojan-downloader became an element of the cyberbuglar chain. You get the downloader on your personal computer, then your system becomes full of different malware. Downloader’s creators obtain the information they will sell in future, and make your PC a part of the botnet, having their money from the botnet selling. When the majority of antimalware tools get the ability to detect and delete this downloader as well as all satellite malware, malware creators inject the ransomware, that is a perfect basis for the final payoff.

As you can see, trojan viruses are not so dangerous theirself, as dangerous the consequences which can be met after their activity.

How have I got the trojan virus?

The largest share of trojan viruses spreading is against programs with questionable and suspicious functionality (program crackers, Windows activators, et cetera). The programs of this type can have no declared functionality, or have the declared functions, but there is still a risk that there is a non-declared thing inside of this app. Such software is usually distributed on the special websites, full of the applications with such properties, or through peer-to-peer networks – ThePirateBay, eMule and so on. There is no chance to have a check if there are any malicious functions inside of the program. The usage of described programs is done at one’s own risk.

Another way of trojan spreading is archives, Microsoft Office files and several other files which are able to contain different programs inside. These files can be found on different forums, where you are looking for a solution for a problem on your PC, as well as ready materials on the theme you need to prepare for your university presentation.

The scheme of trojan virus spreading
The scheme of trojan virus spreading

How to defend yourself against trojans?

There are several quite effective methods, which will help you to keep your PC safe. The majority of advices you can see below are a logical conclusion based on the text above.

Do not use cracked/unlicensed software. Their usage may lead not only to malware injection, but also to numerous lawsuits. In case if you need to use such apps for some reason, test them on the virtual machine to ensure that they really have the functions you need and clean of viruses.

Have the antimalware program installed on your computer. Of course, every computer with Windows onboard has an embedded solution – Microsoft Defender, but it is very vulnerable to malware like spyware or backdoors. These types of malware are capable of disabling the Defender through changing the Group Policies. So, it is recommended to use a separated antivirus, like Loaris Trojan Remover. It is named so not just for a beautiful name: it has a serious database with about 97% of all existing trojan viruses, which is updating hourly. Be sure in your security while using Loaris.

  1. Trojan viruses history on Wikipedia
  2. More about phishing methods

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