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How to remove OSAMiner malware from the operating system

Also Known As: OSAMiner mining trojan
Type: Mac Virus
Damage level: Severe

What is OSAMiner?

OSAMiner is a cryptocurrency miner, a Monero mining Trojan that uses run-only AppleScripts targeting Mac computers.

OSAMiner was first detected in 2015 and is still successfully used by cyber criminals due to its complex structure (use of run-only AppleScript files), which prevents researchers from fully studying it and preventing the attacks.

OSAMiner mining trojan

Research shows that OSAMiner embeds one run-only AppleScript inside another and uses the addresses on public websites to download an open-source Monero miner called XMR-STAK-RX – Free Monero RandomX Miner.

The OSAMiner setup script uses a tool that prevents the infected computer from entering sleep mode. The script is designed to kill running processes belonging to certain popular system monitoring and cleaning tools.

Symptoms of having OSAMiner installed on macOS are system freezes, problems with opening Activity Monitor (Activity Monitor.app), and higher CPU usage.

Threat Summary:
Name OSAMiner mining trojan
Threat Type Cryptocurrency Miner
Detection Names Avast (MacOS:Agent-JE [Trj]), AVG (MacOS:Agent-JE [Trj]), ESET-NOD32 (OSX/OSAMiner.C), Kaspersky (HEUR:Trojan-Downloader.OSX.Chiner.a), Full List (VirusTotal)
Symptoms Higher CPU usage, system freezes, problems with accessing/using Activity Monitor
Distribution methods Pirated copies of games and software (like Microsoft Office, League of Legends)
Damage Higher electricity bills, loss of unsaved data, hardware overhear, decrease in computer performance
Malware Removal (Mac)

To eliminate possible malware infections, scan your Mac with legitimate antivirus software. Our security researchers recommend using Combo Cleaner.
▼ Download Combo Cleaner for Mac
To use full-featured product, you have to purchase a license for Combo Cleaner. Limited seven days free trial available. Combo Cleaner is owned and operated by Rcs Lt, the parent company of PCRisk.com read more.

In summary, cyber criminals distribute OSAMiner to mine Monero cryptocurrency using victims' computer resources/hardware. OSAMiner differs from other miners in that it targets Mac users and is very difficult to detect and analyze.

Some other cryptocurrency mining malware examples are Bird Miner and LoudMiner.

How did malware install on my computer?

Research shows that OSAMiner is distributed via pirated copies of various software programs and games such as, for example, League of Legends and Microsoft Office.

Malware (including ransomware) is usually distributed via malspam campaigns, unofficial software activation ('cracking') tools, Trojans, dubious file/software download sources, and fake software updating tools.

When cyber criminals attempt to distribute malware via malspam campaigns, they send emails that contain malicious attachments or download links for malicious files. Typically, they disguise their emails as official and important. If recipients open the attached file (or a file downloaded via a website link), they cause installation of malicious software.

Cyber criminals commonly attach executable files (.exe), archive files such as RAR, ZIP, PDF documents, JavaScript files and Microsoft Office documents to their emails. Software 'cracking' tools supposedly activate licensed software illegally (bypass activation), however, they often install malicious programs and do not activate any legitimate installed software.

Trojans are other rogue programs that can cause chain infections. I.e., when a Trojan is installed on the operating system, it can install additional malware.

Free file hosting websites, freeware download websites, Peer-to-Peer networks (e.g., torrent clients, eMule), unofficial websites, and third party downloaders are examples of other sources that are used to distribute malware. Cyber criminals disguise malicious files as legitimate and regular. When users download and open them, they inadvertently infect their computers with malware.

Fake software updating tools install malicious software rather than updates/fixes for installed programs, or they exploit bugs/flaws of outdated software that is installed on the operating system.

How to avoid installation of malware

Download software and files from official websites and via direct links. It is not safe to use torrent clients, eMule (or other Peer-to-Peer networks), third party downloaders, unofficial websites or other sources of this kind.

Avoid third party installers. Check "Advanced", "Custom" and other settings, and decline offers to download or install unwanted software. Do not click ads that are displayed on dubious websites, since they can open other untrusted websites or even cause unwanted downloads and installations.

Remove any unwanted, suspicious applications (extensions, add-ons, and plug-ins) that are installed on the browser. The same should be applied to programs of this kind that are installed on the operating system.

Regularly scan your computer with reputable antivirus or anti-spyware software and keep this software up to date.

If your computer is already infected with malware or unwanted software of other type, we recommend running a scan with Combo Cleaner Antivirus for macOS to automatically eliminate them.

Pop-up that appears once the malicious installer for a pirated copy of League of Legends is executed:

osaminer malware system notification that appears after execution of OSAMiner installer

Instant automatic Mac 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 Mac malware. Download it by clicking the button below:
▼ DOWNLOAD Combo Cleaner for Mac By downloading any software listed on this website you agree to our Privacy Policy and Terms of Use. To use full-featured product, you have to purchase a license for Combo Cleaner. Limited seven days free trial available. Combo Cleaner is owned and operated by Rcs Lt, the parent company of PCRisk.com read more.

Quick menu:

Video showing how to remove adware and browser hijackers from a Mac computer:

Potentially unwanted applications removal:

Remove potentially unwanted applications from your "Applications" folder:

mac browser hijacker removal from applications folder

Click the Finder icon. In the Finder window, select "Applications". In the applications folder, look for "MPlayerX", "NicePlayer", or other suspicious applications and drag them to the Trash. After removing the potentially unwanted application(s) that cause online ads, scan your Mac for any remaining unwanted components.

Remove osaminer mining trojan related files and folders:

Finder go to folder command

Click the Finder icon, from the menu bar. Choose Go, and click Go to Folder...

step1Check for adware-generated files in the /Library/LaunchAgents folder:

removing adware from launch agents folder step 1

In the Go to Folder... bar, type: /Library/LaunchAgents

removing adware from launch agents folder step 2
In the “LaunchAgents” folder, look for any recently-added suspicious files and move them to the Trash. Examples of files generated by adware - “installmac.AppRemoval.plist”, “myppes.download.plist”, “mykotlerino.ltvbit.plist”, “kuklorest.update.plist”, etc. Adware commonly installs several files with the same string.

step2Check for adware generated files in the /Library/Application Support folder:

removing adware from application support folder step 1

In the Go to Folder... bar, type: /Library/Application Support

removing adware from application support folder step 2
In the “Application Support” folder, look for any recently-added suspicious folders. For example, “MplayerX” or “NicePlayer”, and move these folders to the Trash.

step3Check for adware-generated files in the ~/Library/LaunchAgents folder:

removing adware from ~launch agents folder step 1


In the Go to Folder bar, type: ~/Library/LaunchAgents

removing adware from ~launch agents folder step 2

In the “LaunchAgents” folder, look for any recently-added suspicious files and move them to the Trash. Examples of files generated by adware - “installmac.AppRemoval.plist”, “myppes.download.plist”, “mykotlerino.ltvbit.plist”, “kuklorest.update.plist”, etc. Adware commonly installs several files with the same string.

step4Check for adware-generated files in the /Library/LaunchDaemons folder:

removing adware from launch daemons folder step 1
In the Go to Folder... bar, type: /Library/LaunchDaemons

removing adware from launch daemons folder step 2
In the “LaunchDaemons” folder, look for recently-added suspicious files. For example “com.aoudad.net-preferences.plist”, “com.myppes.net-preferences.plist”, "com.kuklorest.net-preferences.plist”, “com.avickUpd.plist”, etc., and move them to the Trash.

step 5 Scan your Mac with Combo Cleaner:

If you have followed all the steps in the correct order you Mac should be clean of infections. To be sure your system is not infected run a scan with Combo Cleaner Antivirus. Download it HERE. After downloading the file double click combocleaner.dmg installer, in the opened window drag and drop Combo Cleaner icon on top of the Applications icon. Now open your launchpad and click on the Combo Cleaner icon. Wait until Combo Cleaner updates it's virus definition database and click "Start Combo Scan" button.

scan-with-combo-cleaner-1

Combo Cleaner will scan your Mac for malware infections. If the antivirus scan displays "no threats found" - this means that you can continue with the removal guide, otherwise it's recommended to remove any found infections before continuing.

scan-with-combo-cleaner-2

After removing files and folders generated by the adware, continue to remove rogue extensions from your Internet browsers.

OSAMiner mining trojan removal from Internet browsers:

safari browser iconRemove malicious extensions from Safari:

Remove osaminer mining trojan related Safari extensions:

safari browser preferences

Open Safari browser, from the menu bar, select "Safari" and click "Preferences...".

safari extensions window

In the preferences window, select "Extensions" and look for any recently-installed suspicious extensions. When located, click the "Uninstall" button next to it/them. Note that you can safely uninstall all extensions from your Safari browser - none are crucial for normal browser operation.

  • If you continue to have problems with browser redirects and unwanted advertisements - Reset Safari.

firefox browser iconRemove malicious plug-ins from Mozilla Firefox:

Remove osaminer mining trojan related Mozilla Firefox add-ons:

accessing mozilla firefox add-ons

Open your Mozilla Firefox browser. At the top right corner of the screen, click the "Open Menu" (three horizontal lines) button. From the opened menu, choose "Add-ons".

removing malicious add-ons from mozilla firefox

Choose the "Extensions" tab and look for any recently-installed suspicious add-ons. When located, click the "Remove" button next to it/them. Note that you can safely uninstall all extensions from your Mozilla Firefox browser - none are crucial for normal browser operation.

  • If you continue to have problems with browser redirects and unwanted advertisements - Reset Mozilla Firefox.

chrome-browser-iconRemove malicious extensions from Google Chrome:

Remove osaminer mining trojan related Google Chrome add-ons:

removing malicious google chrome extensions step 1

Open Google Chrome and click the "Chrome menu" (three horizontal lines) button located in the top-right corner of the browser window. From the drop-down menu, choose "More Tools" and select "Extensions".

removing malicious Google Chrome extensions step 2

In the "Extensions" window, look for any recently-installed suspicious add-ons. When located, click the "Trash" button next to it/them. Note that you can safely uninstall all extensions from your Google Chrome browser - none are crucial for normal browser operation.

  • If you continue to have problems with browser redirects and unwanted advertisements - Reset Google Chrome.

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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.

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
OSAMiner mining trojan QR code
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