How to remove BazarLoader backdoor trojan from the operating system?

Also Known As: BazarLoader malware
Type: Trojan
Distribution: Moderate
Damage level: Severe

BazarLoader virus removal guide

What is the BazarLoader backdoor?

Developed by the same threat actors behind TrickBot, BazarLoader is a malicious program, classified as a backdoor/loader trojan. This type of malware is designed to open a "backdoor" to other malignant software. In other words, these trojans operate by downloading/installing additional malware. At the time of research, BazarLoader was used to infect compromised systems with RYUK ransomware. The BazarLoader malware has been observed being proliferated via email spam campaigns, supposedly containing inside information concerning President Donald Trump's health condition. The US President's COVID-19 infection diagnosis has been widely used by cyber criminals for malware distribution and phishing purposes.

BazarLoader malware detections on VirusTotal

As mentioned in the introduction, the purpose of BazarLoader is to infect devices with other malicious programs. With what malware systems can be infected depends on the cyber criminals' modus operandi and the backdoor/loader itself. This software can inject systems with different types of trojans, ransomware, cryptominers and other malware. BazarLoader has been noted infecting affected devices with RYUK ransomware. Malicious programs within this classification operate by encrypting files and/or locking the screen - in order to demand payment (ransoms) for the decryption / access recovery. Typically, ransomware renames the encrypted files, however whether data affected by RYUK is retitled - depends on the malware's variant. This malicious program uses RSA-4096 and AES-256 cryptographic algorithms to encrypt files. It creates ransom notes, containing decryption instructions. Although, specific details (cyber criminals' contact information, ransom size, preferred currency and payment method, etc.) vary from version to version. Meeting the demands of criminals is strongly advised against, as there are no guarantees that they will hold up their end of the bargain (e.g. send the promised decryption keys/tools, etc.). Removing ransomware from an operating system will prevent it from further encryptions; however, removal will not restore already encrypted data. RYUK or other ransomware is not necessarily the payload that BazarLoader will deliver in all infection cases. Another noteworthy detail concerning BazarLoader trojan is its files-less infection process, by which it exploits already existing applications to infect systems - thereby complicating its detection. If it is suspected or known that the BazarLoader trojan (or other malware) has already infected the system - an anti-virus must be used to eliminate it immediately.

Threat Summary:
Name BazarLoader malware
Threat Type Trojan, password-stealing virus, banking malware, spyware.
Detection Names Avast (Win64:CrypterX-gen [Trj]), BitDefender (Trojan.GenericKD.43838874), ESET-NOD32 (A Variant Of Win64/Kryptik.CAK), Kaspersky (Backdoor.Win32.Bazdor.r), Full List (VirusTotal)
Payload RYUK ransomware
Symptoms Trojans 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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BLADABINDIGroooboorBuer Loader and Upatre are a few examples of other malicious programs capable of causing chain infections (i.e. download/installation of additional malware). This software can have other heinous abilities as well, including (but not limited to): file exfiltration, extraction of data from browsers and other applications, keylogging (recording of key strokes), video/audio recording or streaming via compromised machine's webcam/microphone, and so on. Regardless of how malware operates, the end-goal is always the same - to generate profit for the threat actors. All malware infections should be treated as highly dangerous and removed without delay.

How did BazarLoader infiltrate my computer?

The BazarLoader trojan has been spread though email spam campaigns, centered on President Trump's health. The term "spam campaign" is used to define a large-scale operation, during which thousands of scam emails are sent. The deceptive letters proliferating BazarLoader had these subjects/titles "Recent material about the president’s situation", "Recent materials pertaining to the president’s illness", "Newest information about the president’s condition" and "Newest info pertaining to President’s illness"; however, variations and alternatives are likely. The emails themselves suggest that recipients can gain access to inside information on Trump's condition by downloading a document via embedded link. Once the link is clicked, users are redirected to Google Docs, stating that the file is safe. However, instead of downloading a document, a malicious executable is downloaded - which initiates BazarLoader's infection process/chain. To elaborate in general how spam campaigns infect systems - it is done via download links in scam emails and/or infectious files attached to the letters. Virulent files can be in different formats, such as executables (.exe, .run, etc.), archives (ZIP, RAR, etc.), Microsoft Office and PDF documents, JavaScript, and so on. Other popular malware distribution techniques are through untrustworthy download channels, illegal activation tools ("cracks") and illegitimate updaters. Dubious download sources, like: unofficial and free file-hosting websites, Peer-to-Peer sharing networks and other third party downloaders - can offer malware for downloading, disguised as or bundled with ordinary content. Illegal activation ("cracking") tools can download/install malicious software, instead of activating licensed programs. Fake updaters cause infections by exploiting weaknesses of outdated programs and/or by simply installing malware, rather than the promised updates.

How to avoid installation of malware?

Suspicious and/or irrelevant emails must not be opened, especially any attachments or links present in them - as that can result in a high-risk system infection. All downloads must be done from official and verified sources. It is just as important to activate and update programs using functions/tools provided by genuine developers. Illegal activation tools ("cracks") and third party updaters are advised against use, as they are commonly employed to distribute malware. To protect device integrity and user privacy, it is crucial to have a dependable anti-virus/anti-spyware suite installed. Furthermore, this software must be kept updated, used to run regular system scans and to remove detected/potential threats. 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 scam email, distributing BazarLoader trojan:

BazarLoader backdoor spreading email

Text presented in this letter:

Subject: Recent material about the president's situation

 

What we really know and even what we don't about Trump's COVID health problems.

 

Insider information about Trump's] [health condition, please remember to use the code because the record is encrypted: 123

 

Attached document

 

ID

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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 autoruns.zip 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 pcrisk.com 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
BazarLoader 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 BazarLoader malware on your mobile device.
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