Malwarebytes Zoom

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  1. Zoom Download Virus
  2. Zoom App Malware

Malwarebytes Report Confirms Cybercriminals Exploited Pandemic with Shift to Targeted, Sophisticated Attacks SAN FRANCISCO, Feb. 16, 2021 /PRNewswire/ - Malwarebytes™, a leading provider of advanced endpoint protection and remediation solutions, today announced the findings of its annual 'State of Malware.

It’s no surprise that Zoom’s popularity recently skyrocketed. Whether it’s remote employees using it as their main way to stay connected or families finding virtual ways to visit with cousins and grandparents, it’s become a go-to tool for staying in touch as we all practice good social distancing.

Security researcher Felix Seele found that Zoom uses a 'shady' technique to install its Mac app without user interaction using 'the same tricks that are being used by macOS malware,' thus allowing the app to be installed without users providing final consent. On April 2, Zoom issued a fix to resolve the bug. Zoom posted a topic in Resolved Malware Removal Logs Hello.Pls help me im getting random files in temp and when i delete them the apear again after few minutes.When i delete all files from temp my computer works fine but when files apear again my pc is not usable.Pls help ASAP, Thanks.

When I say Zoom’s popularity is off-the-charts high, I’m not kidding. For fun, I compared its recent interests trend to that of other video apps, thanks to some data made available by Google.

The TL;DR: It looks like we were collectively interested in the release of Tiger King on Netflix while also learning more about Zoom and how to change the background image.

Comparison of common video conferencing applications interest over time.

Everyone’s using Zoom … what’s new?

Zoom’s turned into the defacto video conferencing solution – and with that comes both wanted and unwanted attention. While the app provides a great opportunity for us to stay connected, your family, friends and neighbors may not be as security-conscious as you are – making them vulnerable to attack. In this post I’ll detail a recent attack the Expel team identified and share some tips that you can follow to make sure your Zoom downloads are safe.

“In the midst of chaos, there is also opportunity” – Sun Tzu (… for clever attackers)

Attackers are finding new ways to pounce and capitalize on the current global outbreak to target unsuspecting users via some of their most-loved apps and websites.

Which is what we witnessed last week when our SOC identified an incident involving a drive-by download of a fake Zoom installer bundled with malware.

If someone’s downloading Zoom, are they sure they downloaded and installed Zoom directly from their website? With this recent finding, it’s possible that many may have downloaded the installer from a fake website onto their computers – and social distancing isn’t going to help protect you against this particular threat from accessing your sensitive data.

Emerging threat: Zoom installers bundled with malware

I’ll walk you through exactly how this attack happened and will share a few tips for staying safe and avoiding a malware attack like this one.

Take a look at the images below. This is a quick comparison of the malicious, self-extracting Zoom installer property details on the left and a legitimate property details of the installer (MD5: 088999a629a254d54a061eeb1cc8b1e2) on the right.

The property details on the right shows the legitimate installer dropped by the bundled installer on the left.

The bundled Zoom installer was hosted from the malicious website hxxp://zoom-free2[.]com/download/zoominstaller.exe. When executed, a copy of a legitimate Zoom installer and malicious files are written to disk within the directory C:zoominst.

The dropped files are detailed within the table below.

nanohost.exeARKEI/VIDAR Trojan1465a5f6107ba60876e0b8d8024acdad
ZoomInstaller.exeLegitimate installer088999a629a254d54a061eeb1cc8b1e2
Icon_2.icoZoom icon fileea3fea284dbc1ed6f173e42cb6987e39
ContentSet WshShell = CreateObject('WScript.Shell') WshShell.Run 'object73237.bat', 0, false
Content@Echo off
timeout 3
start nanohost.exe

Details of the files that are created within C:zoominst folder.

While the attack successfully installs and launches a legitimate version of Zoom to avoid user suspicion, it also drops a payload named nanohost.exe on the victim’s machine that performs malicious activity.


nanohost.exe (shown above under “filename”) is closely related to, and a variant of, the ARKEI/VIDAR information stealer (InfoStealer) malware family.

nanohost.exe will query system settings, such as timezone, machine ID, hostname, display settings, hardware information, running process information and saving the queried results output to disk with the filename information.txt located within a randomly generated folder name in %PROGRAMDATA%[RANDOM]filesinformation.txt. The malware is profiling the infected system likely to be used for reference by the attacker.

Now let’s look at the format of the output data contained within the information.txt file:

Work Dir: C:ProgramData<RANDOM>
Windows: <OS>
Computer Name: <HOSTNAME>
User Name: <USERNAME>
Display Resolution: <RESOLUTION>
Display Language: <LOCALE>
Keyboard Languages: <LOCALE>
Local Time: <DATE/TIME>
TimeZone: <TZ>
[Hardware]Processor: <CPU SPECS>
CPU Count: <CORES>
VideoCard: <GPU>
[Network]IP: <IP>
Country: <COUNTRY>
City: <CITY>
Coordinates: <LAT/LONG>

———- System [<PID>]


Contents of information.txt

As per the[Network]block within the information.txt file, nanohost.exe will perform an IP geolocation lookup of the victim system using ip-api[.]com/line/. The service returns information about the victim’s public IP address such as: country, city, zip code, latitude, longitude, ISP and other details. The results are saved to information.txt.

Here’s an example of what the outbound HTTP POST request to the IP geolocation lookup service looks like:

HTTP POST request to IP geolocation lookup service.

nanohost.exe is configured to connect to the external, command-and-control (C2) server at wrangellse[.]com for additional execution of arbitrary code. The malware attempts to download additional DLL files staged within the web root directory of the C2 server. The DLL files are written to the victim machine located within the root folder of %PROGRAMDATA%. Based on the naming convention of the DLL files, these are likely used by nanohost.exe to support scraping of sensitive web browser data.

Once the DLL files are downloaded from the C2 server, nanohost.exe accesses and retrieves sensitive data from FTP applications installed such as FileZilla and web browsers installed on the victim machine ranging from Internet Explorer, Google Chrome, Mozilla Firefox, Torch, Uran and various other Chromium-based browsers.

After successful collection and consolidation of host reconnaissance output, browser and FTP application data, nanohost.exe sends an outbound HTTP POST request with the pertinent data within the request body to wrangellse[.]com.

Here’s where the malware established an outbound HTTP POST request to the C2 server.

Outbound HTTP POST request containing host reconnaissance output

The observed network traffic activity generated from nanohost.exe is displayed within the screenshot below.

Packet capture filter display on the destination C2 server.

An overview of process execution spawned from the malware-bundled Zoom installer is summarized below.

Overview of malicious process activity

While there’s plenty more we could discuss around the capabilities of ARKEI/VIDAR trojan, the important message to re-inforce is that malware operators are continuing to adapt and take full advantage of the current, pandemic circumstances, exploiting popular trends to further push their agenda.

If you’re using Zoom …

… then keep these tips in mind as you (or someone you know) is downloading and using the software.

  • For employees, adhere to your organization’s IT policy. Don’t install unapproved software. And if you’re not sure if something’s approved, ask first before downloading it.
  • When using Zoom at home on your own equipment (mobile, PC/laptop), download the software directly from Zoom’s website and make sure it’s secure before installing. Don’t click on a Zoom download link that was sent to you via SMS (for mobile installation), e-mail or a pop-up window that appeared while browsing the web. Instead, go directly to Zoom’s website and navigate to their Downloads page.
  • If you aren’t joining a Zoom meeting through a mobile app, software client or browser extension, go to Zoom’s official website and use their Join A Meeting option to connect directly to the meeting from your browser. Be sure to follow the same rules in the bullet above.
  • Take the time to read through the privacy and security resource guides made available by Zoom.

We’re working on another blog post all about recommended, hardening settings for your Zoom meetings to help avoid potential risks. Stay tuned.

While attackers may use these strange times as an opportunity to strike, remember that there are measures we can all take to protect ourselves.

Stay safe, everyone.

Below are charts that can be used as reference.

MITRE ATT&CK Matrix Table

Initial AccessDrive-by Compromise
ExecutionThird-party Software, User Execution
Defense EvasionHidden Window, Software Packing
Credential AccessCredentials from Web Browsers, Credentials in Files
DiscoveryFile and Directory Discovery, Process Discovery, Query Registry, Software Discovery, System Information Discovery, System Network Configuration Discovery, System Owner/User Discovery, System Time Discovery
CollectionAutomated Collection, Data from Local System
Command And ControlRemote File Copy, Standard Application Layer Protocol
ExfiltrationAutomated Exfiltration, Data Compressed, Exfiltration Over Command and Control Channel

MITRE ATT&CK Matrix Table


Zoom Download Virus

File Path%PROGRAMDATA%vcruntime140.dll
File Path%PROGRAMDATA%softokn3.dll
File Path%PROGRAMDATA%nss3.dll
File Path%PROGRAMDATA%msvcp140.dll
File Path%PROGRAMDATA%mozglue.dll
File Path%PROGRAMDATA%freebl3.dll
File Path%PROGRAMDATA%<RANDOM>filesSoftAuthy
File Pathc:zoominstunin1213.vbs
File Pathc:zoominstobject73237.bat
File Pathc:zoominstnanohost.exe
File Pathc:zoominstZoomInstaller.exe
File Path%USERPROFILE%Downloadszoominstaller.exe
File Nameinformation.txt
File Namepasswords.txt
File Nameld

Indicator of compromise (IOC)




author = '@heyjokim'
description = 'Self-extracting, Zoom installer bundled with malware'
reference = '2c59f16921956b05f97a5b3e208168a6'


$s1 = 'ZoomInstaller.exe'
$s2 = 'Releasesfxrar.pdb'


uint16(0) 0x5A4D and all of ($s*)}

Custom detections

Zoom virus removal guide

What is Zoom virus?

'Zoom virus' is a generic term used to define unwanted or malicious software proliferated under the guise of content relating to the Zoom application/services. Zoom Video Communications is a legitimate conferencing service, providing a cloud-based communication platform that enables people to have audio and video conferences, online meetings and exchange messages via chat. Due to Zoom's accessibility (cross-platform, basic plans available free, etc.) and the current social climate (Coronavirus/COVID-19 pandemic), cyber criminals have begun misusing the company/product name to further their malicious purposes. As Zoom's user base has grown exponentially with the influx of remote workers/students, so has cyber crime targeting this service/app.

During research, it has been observed that cyber criminals spread malicious content using fake Zoom app installers. The executable files of these rogue installers are often named with variations of 'zoom-us-zoom_*******.exe' (the asterisks represent differing words and/or characters). These executables typically launch the InstallCore installer, which is a Potentially Unwanted Application (PUA). InstallCore then installs an unwanted or malicious piece of software. The proliferated programs are varied, depending on the criminals' modus operandi and goals. They might be adware, browser hijackers or other PUAs, as well as Trojans, ransomware, cryptominers or other malware. It has been noted that the name of the Zoom service/application was misused to proliferate Neshta information-stealing malware. Additionally, there has been an increase of domains registered incorporating 'Zoom' within them (e.g. resembling the domain of the genuine website as closely as possible). They are usually disguised as the 'official' Zoom site or as 'trustworthy' third party sites, from which users can supposedly download the Zoom app (thereby, tricking them into downloading malicious content). In fact, these web pages can also be used for phishing purposes. I.e., to steal users' personal information such as their registered Zoom accounts, names, emails, credit card and banking account details (e.g. as billing information for payable features), and so on. Therefore, to ensure device integrity and user safety, use only official download sources. If you suspect that unwanted/malicious software has already infiltrated the system, use an antivirus suite to eliminate it immediately.

Threat Summary:
NameZoom malware
Threat TypeTrojan, password-stealing virus, banking malware, spyware.
Detection Names (malicious installer)
Avast (FileRepMalware), DrWeb (Trojan.InstallCore.3943), ESET-NOD32 (Win32/InstallCore.AZE.Gen Potentially Unw), Malwarebytes (PUP.Optional.InstallCore.Generic), Full List (VirusTotal).
PayloadVarious PUAs and malware (e.g., njRAT, cryptominers).
SymptomsTrojans 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 methodsInfected email attachments, malicious online advertisements, social engineering, software 'cracks'.
DamageStolen passwords and banking information, identity theft, the victim's computer added to a botnet.
Malware Removal (Windows)

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Cyber criminals and scammers often incorporate legitimate products, platforms, services organizations, institutions, companies, etc. into their schemes in some fashion. This increases their success rate, as people are less likely to suspect something with which they are familiar. The Zoom Video Communications software is by far not the only product/service included in scams. For example, Microsoft Teams and Google Classroom services have been similarly misused. These legitimate entities have no connection to these scams that misuse their names.

How did Zoom virus infiltrate my computer?

The 'Zoom virus' has been proliferated via fake Zoom installation set-ups. Rogue installers are often downloaded from untrusted download sources such as unofficial and free file-hosting websites, Peer-to-Peer sharing networks (BitTorrent, eMule, Gnutella, etc.) and other third party downloaders, however, such dubious download channels can offer malicious content under various guises. Other common malware proliferation methods are through Trojans, spam campaigns, fake updaters and illegal activation ('cracking') tools. Trojans are malicious programs that have varied capabilities, which can include the capability to cause chain infections (i.e., download/installation of additional malware). The term 'spam campaign' defines a large scale operation, during which deceptive/scam emails are sent by the thousand. These messages have infectious files attached to them or alternatively contain download links of malicious content. Infectious files come in a number of formats such as archive (RAR, ZIP, etc.) and executable (.exe, .run, etc.) files, Microsoft Office and PDF documents, JavaScript, etc. When these files are executed, run or otherwise opened, the infection process starts. Rogue updaters infect systems by exploiting weaknesses of outdated software and/or simply by installing malware rather than the promised updates. 'Cracking' tools can download/install malicious programs, rather than active the licensed product.

How to avoid installation of malware

You are strongly advised to use only official and verified download sources. It is also important to activate and update products with tools/functions provided by genuine developers. Illegal activation tools ('cracks') and third party updaters should be avoided, as they are commonly used to proliferate malware. Suspicious and/irrelevant emails should not be opened, especially those with any attachments or links found in them, since this can result in high-risk infection. To protect device and user safety, it is paramount to have a reputable anti-virus/anti-spyware suite installed. Furthermore, this software must be kept up to date, used to run regular system scans and to remove detected threats/issues. 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.

Screenshot of another malicious installer:

Yet another deceptive Zoom installer which targets German users and bundles a variety of unwanted applications:


Detections of a fake Zoom installer (which distributes njRAT) in VirusTotal:

Detections of a fake Zoom installer (which distributes cryptominers) in VirusTotal:

Screenshot of the legitimate and official Zoom website:

Screenshot of a malicious website used to promote a fake Zoom installer setup:

Update 21 May 2020 - Recently, two malicious Zoom installers have been detected. One is designed to inject a 'backdoor virus', which provides cyber criminals with remote access to the infected device. Once the backdoor is injected, the genuine Zoom installer will be opened so that users do not become suspicious. The other malicious installer is designed to spread the Devil Shadow botnet. Devil Shadow not only controls the system, but can also spy the user by taking screenshots, using the webcam and so on. You can find more technical details in the Trend Micro's article.

Screenshot of yet another deceptive Zoom download website. The setup installs a modified Zoom application which connects to a remote server and downloads/installs either IcedID or Cobalt Strike trojans:

Instant automatic malware removal:Manual threat removal might be a lengthy and complicated process that requires advanced computer 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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Quick menu:

  • STEP 1. Manual removal of Zoom virus.
  • STEP 2. Check if your computer is clean.

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:

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:


Download a program called Autoruns. This program shows auto-start applications, Registry, and file system locations:

Restart 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.

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.

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.

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

Extract the downloaded archive and run the Autoruns.exe file.

In 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.

Check 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'.

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.

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.

Zoom App Malware

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