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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 IT 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 adware-related files and folders

Mac Go To Folder step

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

Mac removing related files and folders - step 1Check for adware generated files in the /Library/LaunchAgents/ folder:

Mac go to /Library/LaunchAgents - step 1

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

Mac go to /Library/LaunchAgents - 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 exact same string.

Mac removing related files and folders - step 2Check for adware generated files in the ~/Library/Application Support/ folder:

Mac go to /Library/Application Support - step 1

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

Mac go to /Library/Application Support - 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.

Mac removing related files and folders - step 3Check for adware generated files in the ~/Library/LaunchAgents/ folder:

Mac go to ~/Library/LaunchAgents - step 1

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

Mac go to ~/Library/LaunchAgents - 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 exact same string.

Mac removing related files and folders - step 4Check for adware generated files in the /Library/LaunchDaemons/ folder:

Mac go to /Library/LaunchDaemons - step 1

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

Mac go to /Library/LaunchDaemons - 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.

Mac removing malware related files and folders - step 5Scan your Mac with Combo Cleaner:

If you have followed all the steps correctly, your Mac should be clean of infections. To ensure 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 the 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 its virus definition database and click the "Start Combo Scan" button.

Mac remove malware with Combo Cleaner - step 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.

Mac remove malware with Combo Cleaner - step 2

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

Remove malicious extensions from Internet browsers

Safari iconRemove malicious Safari extensions:

Removal of malicious extensions in Safari - step 1

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

Removal of malicious extensions in Safari - step 2

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 regular browser operation.

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

Google Chrome logoRemove malicious extensions from Google Chrome:

Removal of malicious extensions in Google Chrome - step 1

Click the Chrome menu icon Google Chrome menu icon (at the top right corner of Google Chrome), select "More Tools" and click "Extensions". Locate all recently-installed suspicious extensions, select these entries and click "Remove".

Removal of malicious extensions in Google Chrome - step 2

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

Mozilla Firefox logoRemove malicious extensions from Mozilla Firefox:

Removal of malicious extensions in Mozilla Firefox - step 1

Click the Firefox menu firefox menu icon (at the top right corner of the main window) and select "Add-ons and themes". Click "Extensions", in the opened window locate all recently-installed suspicious extensions, click on the three dots and then click "Remove".

Removal of malicious extensions in Mozilla Firefox - step 2

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

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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.

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