Winstar Virus

Also Known As: WinstarNssmMiner virus
Type: Trojan
Damage level: Severe

What is Winstar?

Winstar (also known as WinstarNssmMiner) is a rogue application based on a legitimate open-source miner called XMRIG. Winstar infiltrates the system and starts misusing system resources to mine Monero cryptocurrency. Although XMRIG is legitimate, Winstar is considered to be a virus, since it infiltrates systems and mines cryptocurrency without users' consent.

Winstar malware

Cryptomining is utilization of computer resources to solve various mathematical problems. The more powerful computer available, the more problems can be solved and, thus, the more revenue is generated. Buying high-end hardware can be costly.

Therefore, to avoid this issue, cyber criminals distribute malicious cryptomining software that infiltrates computers and employs them to mine cryptocurrency. In this case, Winstar uses systems' CPUs to mine Monero cryptocurrency. Be aware that the mining process can load processors up to 100%.

This makes the system virtually unusable and unstable - it barely responds and can crash, resulting in permanent data loss (unsaved documents and so on). In addition, fully-loaded components generate excessive heat and within the certain circumstances (bad cooling systems, high room temperatures, etc.), mining cryptocurrencies might cause hardware to overheat.

In summary, the presence of a cryptomining malware such as Winstar can lead to significant financial and data losses. Winstar also has an unusual feature that hinders the removal process. One of Winstar's processes in Windows Task Manager is called "svchost.exe".

If, by any means, the user detects this process and tries to terminate it, Winstar immediately crashes the system. The malware automatically self-executes on each system startup, and so the mining process continues once the system is rebooted.

Threat Summary:
Name WinstarNssmMiner virus
Threat Type Trojan, Password stealing virus, Banking malware, Spyware
Symptoms Trojans are designed to stealthily infiltrate victim's computer and remain silent thus no particular symptoms are clearly visible on an infected machine.
Distribution methods Infected email attachments, malicious online advertisements, social engineering, software cracks.
Damage Stolen banking information, passwords, identity theft, victim's computer added to a botnet.
Malware Removal (Windows)

To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Combo Cleaner.
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Winstar shares many similarities with dozens of other trojan-type viruses, such as XMR Miner, BitCoinMiner, AV64N.exe, etc. These are developed by different cyber criminals. Some disguise themselves as legitimate applications, whilst others remain hidden.

Their only purpose is to generate revenue for the developers by mining various cryptocurrencies. The presence of these viruses might lead to significant financial and data loss. Eliminating cryptomining malware is paramount.

How did Winstar infiltrate my computer?

It is currently not confirmed how cyber criminals proliferate Winstar, however, these viruses are often distributed using trojans, spam email campaigns, peer-to-peer (P2P) networks, unofficial software download sources, and fake software update tools. Trojans cause chain infections - one virus proliferates another.

Spam campaigns are used to distribute malicious attachments that, once opened, download and install viruses. P2P networks (torrents, eMule, etc.) and other third party download sources (free file hosting sites, freeware download websites, and so on) present malicious executables as legitimate software.

In this way, users are tricked into downloading and installing malware. Fake updaters infect the system by exploiting outdated software bugs/flaws or simply downloading and installing malware rather than updates. In addition, Winstar's installer checks whether the system is running Avast or Kaspersky anti-virus suites. If so, it will self-terminate and the system will not be infected.

How to avoid installation of malware?

Lack of knowledge and careless behavior are the main reasons for computer infections - caution is the key to safety. Therefore, we strongly advise you to pay close attention when browsing the Internet and downloading/installing software. Think twice before opening email attachments.

If the file is irrelevant and has been received from a suspicious/unrecognizable email address, it should never be opened. Software should be downloaded from official sources only, using direct download links. You should avoid using third party downloaders/installers, since they are likely to include rogue apps. Furthermore, keep installed software up-to-date.

To achieve this, however, use only implemented functions or tools provided by the official developers. Having a reputable anti-virus/anti-spyware suite installed and running is also paramount. If you believe that your computer is already infected, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate infiltrated malware.

CPU utilization during the mining process:

Winstar mining cryptocurrency

Instant automatic malware removal: Manual threat removal might be a lengthy and complicated process that requires advanced IT skills. Combo Cleaner is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:
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How to remove malware manually?

Manual malware removal is a complicated task - usually it is best to allow antivirus or anti-malware programs to do this automatically.

To remove this malware we recommend using Combo Cleaner Antivirus for Windows. If you wish to remove malware manually, the first step is to identify the name of the malware that you are trying to remove. Here is an example of a suspicious program running on a user's computer:

malicious process running on user's computer sample

If you checked the list of programs running on your computer, for example using task manager, and identified a program that looks suspicious, you should continue with these steps:

manual malware removal step 1 Download a program called Autoruns. This program shows auto-start applications, Registry, and file system locations:

screenshot of autoruns application

manual malware removal step 2Restart your computer into Safe Mode:

Windows XP and Windows 7 users: Start your computer in Safe Mode. Click Start, click Shut Down, click Restart, click OK. During your computer start process, press the F8 key on your keyboard multiple times until you see the Windows Advanced Option menu, and then select Safe Mode with Networking from the list.

Safe Mode with Networking

Video showing how to start Windows 7 in "Safe Mode with Networking":

Windows 8 users: Start Windows 8 is Safe Mode with Networking - Go to Windows 8 Start Screen, type Advanced, in the search results select Settings. Click Advanced startup options, in the opened "General PC Settings" window, select Advanced startup. Click the "Restart now" button.

Your computer will now restart into the "Advanced Startup options menu". Click the "Troubleshoot" button, and then click the "Advanced options" button. In the advanced option screen, click "Startup settings". Click the "Restart" button. Your PC will restart into the Startup Settings screen. Press F5 to boot in Safe Mode with Networking.

Windows 8 Safe Mode with networking

Video showing how to start Windows 8 in "Safe Mode with Networking":

Windows 10 users: Click the Windows logo and select the Power icon. In the opened menu click "Restart" while holding "Shift" button on your keyboard. In the "choose an option" window click on the "Troubleshoot", next select "Advanced options". In the advanced options menu select "Startup Settings" and click on the "Restart" button.

In the following window you should click the "F5" button on your keyboard. This will restart your operating system in safe mode with networking.

windows 10 safe mode with networking

Video showing how to start Windows 10 in "Safe Mode with Networking":


manual malware removal step 3Extract the downloaded archive and run the Autoruns.exe file.

extract autoruns.zip and run autoruns.exe

manual malware removal step 4In the Autoruns application, click "Options" at the top and uncheck the "Hide Empty Locations" and "Hide Windows Entries" options. After this procedure, click the "Refresh" icon.

Click 'Options' at the top and uncheck 'Hide Empty Locations' and 'Hide Windows Entries' options

manual malware removal step 5Check the list provided by the Autoruns application and locate the malware file that you want to eliminate.

You should write down its full path and name. Note that some malware hides process names under legitimate Windows process names. At this stage, it is very important to avoid removing system files. After you locate the suspicious program you wish to remove, right click your mouse over its name and choose "Delete".

locate the malware file you want to remove

After removing the malware through the Autoruns application (this ensures that the malware will not run automatically on the next system startup), you should search for the malware name on your computer. Be sure to enable hidden files and folders before proceeding. If you find the filename of the malware, be sure to remove it.

searching for malware file on your computer

Reboot your computer in normal mode. Following these steps should remove any malware from your computer. Note that manual threat removal requires advanced computer skills. If you do not have these skills, leave malware removal to antivirus and anti-malware programs.

These steps might not work with advanced malware infections. As always it is best to prevent infection than try to remove malware later. To keep your computer safe, install the latest operating system updates and use antivirus software.

To be sure your computer is free of malware infections, we recommend scanning it with Combo Cleaner Antivirus for Windows.

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About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for pcrisk.com since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

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Malware activity

Global malware activity level today:

Medium threat activity

Increased attack rate of infections detected within the last 24 hours.

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