How to Open .js Files ( Javascript Hidden Virus) - How to, Technology and PC Security Forum |

How to Open .js Files ( Javascript Hidden Virus)

how-to-open-do-not-open-js-files-sensorstechforum-comSince many of the users on our forum and on our complaint e-mails have reported to be victims of infections caused by .js files(JavaScript source code file format) we have decided to serve the need of knowledge our readers should have and educate them how to protect themselves from malicious execution of a JavaScript that may render their files equal to garbage and make them pay a hefty sum. Bear in mind, we will provide the best advices on our abilities, but even the best advise won’t protect you if you do not pay attention to what you are doing while browsing on a daily basis. Let us begin!

The E-mail

This segment is the most important piece of education you will ever receive if you are a beginner, because it will briefly teach you how to spot the difference between fake e-mail messages and actual e-mails. This is also due to the fact that the most often cause of infection by .js files viruses is via e-mail attachments. So when we are talking about .js files protection, we are also addressing spam e-mail protection as well.

The first step when receiving an e-mail and deciding whether or not to open a .js file in it is to have a system. Such system is very simple to memorize. If I could summarize it, I would definitely use this sentence:

“Start from the top!”

The “top” is the subject of the e-mail that is sent to you and the source e-mail it is sent from. Here you can sort out the cheap e-mails which you can immediately delete even without having to open them. These are the so-called “promotion” and “important” e-mails that are not from organizations, but different individuals that you have never met before. Usually, people tend to write e-mail topics of something familiar to the user who they are sending the message to. Otherwise, why would have provided your e-mail address to specific people for contact, right?


But then again, what if the message does not have a subject or what if it is sent by a company, like Amazon, for example (see the picture below). And what if the e-mail is saying that your PayPal account is suspended? The counter reaction to this in case you are not sure is to use a secure environment when opening the e-mail.Also, bear in mind of the obvious, and this is if a .js file is portrayed to you as a document in an e-mail, it may not be, because it is highly untypical for documents to be in JavaScript.


One solution is to use a sandbox application that “wraps” your web browser or e-mail client (Mozilla Thunderbird, Microsoft Outlook) in a secure encryption on which if the ransomware infection malware is activated, may immediately shut down because it will be stopped inside the program. One very good example for a sandbox application is a neat little app, called Sandboxie which we tested below. It even has the option to auto wrap every program you start in a sandbox automatically without affecting the performance of your computer even the slightest.


However, some sophisticated viruses and malware who run on .js to infect users may be coded and obfuscated with expensive obfuscators and exploit kits that may even go as far as through the sandbox application itself. Here is where you will need an advanced protection tool against these programs when you do your e-mailing – an advanced anti-malware tool is just the thing for you. Unlike traditional antivirus programs, most anti-malware programs are more frequently updated, and they are not just focused on .js malware, but on other suspicious files roaming around in spam e-mails carrying what may just be the lasts Locky or Cerber viruses.

There are a variety of anti-malware programs to choose from out there, and many would argue that the more well-known a security software is, the more it becomes a target for malware, because of the higher interest in it. This is why there should be a balance between a tool on which the hackers have little intelligence while at the same time is frequently maintained and updated. The best choice is a tool that will have a second-generation heuristic update system. This means that if the latest Locky hits in the U.S., the program on your computer should know about this and have the heuristics as fast as possible after this “zero patient” type of infection. One good example for such tool is Heimdal’s professional version, which we have kindly reviewed for you below and in case you do not seem to be fond of it it there are many other tools out there amongst which you can choose.


What If I Don’t Have the Time or Experience To Check Every E-mail?

In case the situation is that dire, or you are going to be educating someone who is systematically becoming infected via e-mail and via JavaScript and other types of files, do not worry. Explaining the situation to the inexperienced user may not be successful even if you repeat It over and over again. This is why we have a brilliant idea which can help protect your daily e-mailing if you are running a Windows OS and this is to use a virtual Android OS straight on your Windows device. Craftily, right?

The idea for this unexpectedly smart solution is that most spam e-mails are designed to trick Windows users into becoming infecting with malware. Surely, there is a lot of malware written for Android, but provided a little education and malware writers prefer malicious URLs via fake advertisements or suspicious apps to infect Android users, not e-mail. More to it than that, Android devices can also be additionally secured from .js files infection with an antivirus software and other utilities and app monitors, which is great. One app that is the leader and is very simple to use (install and start) is called Nox App Player, and after using it, we felt convinced in its stability as well as security


What about Malicious URLs?

Malicious URLs are a very sophisticated method of infection and very effective as well. This is why if the proper script is written to counter your defenses, neither of the tools above may save you. Here is where we talk about direct protection against any form of malicious JavaScript files. To secure your computer, this way, especially if you are using a browser instead of an e-mail client is to educate yourself in scanning URLs manually before opening. I know, it looks complicated at the start, but bear in mind that it can be significantly simplified with free browser add-ons, like VTzilla,’s web browser add-on. Need I remind you that VIrusTotal is most likely the one of the largest (if not, the largest) web database for malware and it not only uses the combination of a wide database of malicious .js files being detected 24/7 but it also learns to detect any URL’s and malicious JavaScripts before you even opened them. All it takes to right click on the URL before opening and scan it.

What If the Inevitable Happens?

If you are using any of those beginner tools, regularly updating your operating system, etc. and still manage to become infected somehow with a .js files attack, good data management is crucial to your survival from the devastation. Below, you may find more information on how to safely store your important files and protect them from .js files viruses.


Since a lot of malware including ransomware, now may not only slither other viruses on your computer if it becomes its victim, but it may also spread worms or make the computer a part of a botnet (bot network). This makes all of the other computers connected to the same network endangered, and they may not have such defensive tools. This is why, before all, your first deal of business is to disconnect the computer from the internet “the hardware way”. This will prevent any malicious packets to travel on your LAN and infect the other devices in it. From there, you can begin coping with the situation.


Ventsislav Krastev

Ventsislav has been covering the latest malware, software and newest tech developments at SensorsTechForum for 3 years now. He started out as a network administrator. Having graduated Marketing as well, Ventsislav also has passion for discovery of new shifts and innovations in cybersecurity that become game changers. After studying Value Chain Management and then Network Administration, he found his passion within cybersecrurity and is a strong believer in basic education of every user towards online safety.

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