How to uninstall Oski malware from a computer?

Also Known As: Oski malware
Type: Trojan
Distribution: Low
Damage level: Severe

Oski virus removal guide

What is Oski?

Oski is a malicious program which operates as an information stealer. After infiltration Oski attempts to access various sensitive information so that cyber criminals behind it could misuse it to generate revenue in various ways. Research shows that this information stealer is being distributed through deceptive pages that get opened due to hijacked router's DNS settings.

Oski malware

Cyber criminals attempt to trick users into installing Oski by hijacking router's DNS settings so that web browsers would open deceptive pages/pop-ups encouraging visitors to install some application which supposed to deliver latest information relate to the Coronavirus (COVID-19). Although, the file that gets downloaded through those malicious pages is designed to install Oski. As mentioned in the introduction, Oski is a malicious program which is capable of stealing sensitive information. It targets data from browsers such as cookies and browsing history, autofill data, saved login credentials. Also, it attempts to steal databases that contain 2FA (two-factor authentication) data, cryptocurrency wallets, text files, can take screenshots of victim's desktop and perform some other actions. Basically, it means that cyber criminals behind Oski could be able to hijack various accounts, including social media, email, cryptocurrency trading accounts, and so on. Moreover, they could be capable of hijacking accounts that have an additional layer of protection beyond passwords as well. Cyber criminals may misuse stolen accounts to make fraudulent purchases, transactions, spread spam campaigns, trick other users into paying them money, steal identities, etc. Also, they could be able to access text files that may confidential information, make screenshots of them when victim's open them, or capture any other computing activities. Victims of Oski attack may suffer monetary loss, have their identities stolen, experience problems related to online privacy, browsing safety and other serious issues. Therefore, this malware must be removed from infected systems as soon as possible.

Threat Summary:
Name Oski malware
Threat Type Trojan, password-stealing virus, banking malware, spyware.
Detection Names Avast (Win32:DropperX-gen [Drp]), BitDefender (Trojan.GenericKD.42887257), ESET-NOD32 (A Variant Of MSIL/TrojanDownloader.Small.CCK), Kaspersky (HEUR:Trojan.MSIL.Chapak.gen), Full List (VirusTotal)
Symptoms Information stealing Trojans like Oski are designed to stealthily infiltrate the victim's computer and remain silent, and 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 passwords and banking information, identity theft, the victim's computer added to a botnet.
Malware Removal (Windows)

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There are many various information stealers on the Internet, here are a couple of examples: ArkeiStealer, RedLineStealer and CStealer. As a rule, programs of this type are designed to steal a range of sensitive information that could be misuses to generate revenue in one or another way. It is common that cyber criminals behind them target banking-related details, however, quite often they seek to steal other sensitive information as well.

How did Oski infiltrate my computer?

Research shows that cyber criminals attempt to trick users into infecting computers with Oski through a deceptive page offering to download and install an application which supposed to deliver latest updates on COVID-19. This page gets opened when users have their router's DNS settings hijacked by cyber criminals. To be more precise, when those settings are configured to use DNS servers operated by the attackers/cyber criminals. Those servers send victims to an address which displays a page encouraging them to download and install Oski which is disguised as a legitimate app from WHO (World Health Organization).

How to avoid installation of malware?

Software and files should never be downloaded from unofficial pages. Other channels like third party downloaders (and installers), Peer-to-Peer networks (e.g., torrent clients, eMule), freeware download pages, should not be used too. The safest way to download files and programs is by using official websites and direct links. Attachments and website links in irrelevant emails should not be trusted (opened). Especially if such emails are sent from unknown, suspicious addresses. Simply said, email contents should be opened only when there is not reason to think that it may cause installation of malware or other damage. Installed software should be updated and activated with tools and/or functions that are designed by official developers. Both third party activation and updating tools can be designed to spread malware. Besides, it is not legal to use tools that supposed to activate licensed programs for free. Operating system should be regularly scanned for threats with a reputable antivirus or anti-spyware software, detected threats must be eliminated as soon as possible. If you believe that your computer is already infected, we recommend running a scan with Malwarebytes for Windows to automatically eliminate infiltrated malware.

Screenshot of a deceptive website offering visitors to install application which supposed to deliver latest updates on COVID-19:

oski stealer pop-up on a deceptive website

Text presented within this site:

COVID-19 Inform App

Install this app, to have the latest information and instructions about coronavirus (COVID-19).

World Health Organization.
Part of the U.N. Sustainable Development Group.

Update May 13, 2020 - Cyber criminals have recently started spreading Oski Stealer via fake hacking tools that supposedly allow to perform various illegal actions in Counter Strike: Global Offensive (CS:GO) video game. Such tools are often promoted via YouTube videos. The videos display how the tool supposedly works and provide download links in the video description. Once an unsuspecting user executes the fake hacking tool, Oski Stealer instantly infiltrates the system.

Instant automatic malware removal: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Malwarebytes 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 Malwarebytes 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 1Download 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 and run autoruns.exe

manual malware removal step 4In the Autoruns application, click "Options" at the top and uncheck "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 Malwarebytes for Windows.

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 since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Removal Instructions in other languages
Malware activity

Global malware activity level today:

Medium threat activity

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

QR Code
Oski malware QR code
A QR code (Quick Response Code) is a machine-readable code which stores URLs and other information. This code can be read using a camera on a smartphone or a tablet. Scan this QR code to have an easy access removal guide of Oski malware on your mobile device.
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