How to eliminate GuLoader from the operating system?

Also Known As: GuLoader downloader
Type: Trojan
Distribution: Moderate
Damage level: Severe

GuLoader virus removal guide

What is GuLoader?

GuLoader is a malware downloader that cyber criminals use to spread various Remote Access Trojans (RATs) and other trojan-type programs. They use GuLoader with a purpose to infect computers with malicious programs that can be used as tools to steal sensitive information, infect computers with other malware, and perform other actions that would help cyber criminals to generate revenue.

GuLoader malware

Research show that GuLoader is used to proliferate various RATs and stealers (malicious programs that are designed to collect sensitive data). RATs are programs that give cyber criminals control over infected computers/operating systems and allows them to log keystrokes, download and execute various files, access webcam, microphone, make screenshots, monitor computing activity, manage (copy, rename, delete) files, and perform other actions. In most cases cyber criminals attempt to steal credit card details, credentials (passwords, logins) of accounts that could be used to make fraudulent purchases, transactions and/or generate revenue in other ways. It is common that they use RATs as tools to infect computers with other malware like ransomware. Furthermore, GuLoader is commonly used to infect computers with malicious programs that are designed to steal sensitive information. Cyber criminals behind information stealers usually target banking-related details, passwords, logins, data saved on clipboard, and other sensitive information too. Basically, cyber criminals attempt to infect operating systems with GuLoader so they could cause chain infections. In other words, to infect computers wit some other malware that would help them to generate revenue. Victims of malware that is proliferated through GuLoader risk to suffer monetary and/or data loss, become victims of identity theft, experience problems related to online privacy, and other serious issues. Therefore, GuLoader or its payload is already installed on the operating system, then it should be eliminated from it immediately.

Threat Summary:
Name GuLoader downloader
Threat Type Malware downloader
Detection Names Avast (Win32:Trojan-gen), BitDefender (Trojan.GenericKD.33531900), ESET-NOD32 (A Variant Of Win32/Injector.EKYU), Kaspersky (Backdoor.MSIL.NanoBot.bbks), Full List (VirusTotal)
Payload GuLoader can be used to infect systems with Agent Tesla, FormBook, LokiBot, NetWire, Remcos, Vidar and other malicious programs
Symptoms Programs like GuLoader 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, data and/or monetary loss, problems with online privacy

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Some examples of malicious programs that cyber criminals can spread via GuLoader are Agent Tesla, FormBook, LokiBot, NetWire, Remcos and Vidar. However, they may use this downloader as a tool to infect systems with other malicious programs as well. In one way or another, their main goal is to get access to personal information, accounts or perform other actions that would give them an ability to generate revenue in fraudulent ways.

How did GuLoader infiltrate my computer?

It is common that cyber criminals spread various malicious programs through spam campaigns, unreliable download channels, unofficial (fake) software updating tools, Trojans and software 'cracking' tools/unofficial activators. Spam campaigns are often used as tools to trick recipients into infecting systems through malicious attachments (or web links that download malicious files). When opened, those files or attachments install malware. Examples of files that cyber criminals include in/attach to their emails are Microsoft Office, PDF documents, archive files (e.g., RAR, ZIP), executable files (like .exe) and JavaScript files. Peer-to-Peer networks (like torrent clients, eMule), freeware download websites, free file hosting websites, third party downloaders, unofficial pages, etc., can be used as tools to distribute malicious programs too. Cyber criminals use them to host malicious files that, if downloaded and opened/executed, infect operating system with some high-risk malware. It is worthwhile to mention that third party installers can be designed to proliferate malware too. Unofficial tools that supposed to update installed software usually infect operating systems by exploiting bugs, flaws of the outdated software or by installing malicious software instead of updates, fixes. Trojans can cause damage only if they already installed. These malicious programs often are designed to open backdoors for other malware. In other words, they cause chain infections. Software 'cracking' tools are used by users who seek to activate software for free (bypass its activation). However, it is common that tools of this type often install malicious software instead.

How to avoid installation of malware?

Website links and attachments that are presented in irrelevant emails should not be trusted, especially if such emails are sent from unknown, suspicious addresses. If there is a reason to think that an email is untrustworthy, then the best option is to simply ignore it and leave its contents unopened. Software should be downloaded from official websites and via direct download links. Third party downloaders, installers, unofficial pages and other channels, tools should not be used. Furthermore, installed software must be updated and/or activated only with tools and/or functions that are designed (provided) by official developers. Third party updaters and activators can be (and often are) designed to install malware. Besides, it is not legal to bypass activation of licensed software with third party tools. One more way to keep operating systems safe is to scan them for viruses and other threats regularly. These scans should be performed with a reputable antivirus or anti-spyware software. If you believe that your computer is already infected, we recommend running a scan with Spyhunter for Windows to automatically eliminate infiltrated malware.

Appearance of a Coronavirus-related spam email used to spread GuLoader malware (attachment is a .gz archive which contains an executable - "QUOTE 2020.PDF.exe"):

Coronavirus-related spam email used to spread GuLoader

Text presented within this email:

Subject: URGENT NEED: U.S. Department of Health & Human Services/COVID-19 Face Mask/ Forehead thermometers

Due to the wild spread of COVID-19 all over the United States, the U.S. Department of Health & Human Services is in urgent demand of Face mask and forehead thermometers for it's citizens.

I will like if your company can supply us with the attached products list.

Awaiting your urgent reply.

Best regards.

Sheila Conley

U.S. Department of Health & Human Services
200 Independence Avenue, S.W.

Instant automatic malware removal: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Spyhunter 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 Spyhunter 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 Spyhunter 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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Malware activity

Global malware activity level today:

Medium threat activity

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

QR Code
GuLoader downloader 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 GuLoader downloader on your mobile device.
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