How to remove OSAMiner malware from the operating system
Written by Tomas Meskauskas on (updated)
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.
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.
| 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. |
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:
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:
- What is OSAMiner?
- STEP 1. Remove PUA related files and folders from OSX.
- STEP 2. Remove rogue extensions from Safari.
- STEP 3. Remove rogue add-ons from Google Chrome.
- STEP 4. Remove potentially unwanted plug-ins from Mozilla Firefox.
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:
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
Click the Finder icon, from the menu bar. Choose Go, and click Go to Folder...
Check for adware generated files in the /Library/LaunchAgents/ folder:
In the Go to Folder... bar, type: /Library/LaunchAgents/
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.
Check for adware generated files in the ~/Library/Application Support/ folder:
In the Go to Folder... bar, type: ~/Library/Application Support/
In the "Application Support" folder, look for any recently-added suspicious folders. For example, "MplayerX" or "NicePlayer", and move these folders to the Trash.
Check for adware generated files in the ~/Library/LaunchAgents/ folder:
In the Go to Folder... bar, type: ~/Library/LaunchAgents/
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.
Check for adware generated files in the /Library/LaunchDaemons/ folder:
In the "Go to Folder..." bar, type: /Library/LaunchDaemons/
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.
Scan 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.
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.
After removing files and folders generated by the adware, continue to remove rogue extensions from your Internet browsers.
Remove malicious extensions from Internet browsers
Remove malicious Safari extensions:
Open the Safari browser, from the menu bar, select "Safari" and click "Preferences...".
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.
Remove malicious extensions from Google Chrome:
Click the 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".
- If you continue to have problems with browser redirects and unwanted advertisements - Reset Google Chrome.
Remove malicious extensions from Mozilla Firefox:
Click the Firefox menu 
(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".
- If you continue to have problems with browser redirects and unwanted advertisements - Reset Mozilla Firefox.
Outstanding!
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