SysJoker Malware (Mac)

What is SysJoker?

SysJoker is a backdoor-type malicious program. It operates by injecting compromised systems with other malware. SysJoker is also a cross-platform program; hence, in addition to macOS, it also targets Windows and Linux operating systems.

SysJoker malware detections on VirusTotal

SysJoker overview

At the time of writing, SysJoker's capabilities were the same regardless of the infected platform. As mentioned in the introduction, this malicious program is designed to cause chain infections (i.e., download/install additional malware).

To expand upon the most common malicious software, "trojan" is a term that defines an incredibly varied type of malware. Trojans may be able to exfiltrate content (files and data) from the system, extract information from browsers and other installed applications, record keystrokes (keylogging), record/livestream the desktop or audio/video via microphones and cameras, enable remote control over devices (RATs - Remote Access Trojans), and so on.

Ransomware encrypts data and demands ransoms for the decryption (screenlocker types may not encrypt files and instead just lock the screen for the same purpose). Cryptominers are malicious programs that abuse system resources (potentially to the point of system failure) to generate cryptocurrency.

To summarize, infections with malware like SysJoker, can lead to data loss, hardware damage, serious privacy issues, financial losses, and identity theft.

Threat Summary:
Name	SysJoker virus
Threat Type	Mac malware, Mac virus, Trojan, password-stealing virus, spyware.
Detection Names	Avast (MacOS:Joker-A [Trj]), Combo Cleaner (Trojan.GenericKD.47868192), ESET-NOD32 (OSX/SysJoker.A), Kaspersky (HEUR:Backdoor.OSX.SysJoker.gen), Full List Of Detections (VirusTotal)
Symptoms	Trojans-type malware is 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, fake Adobe Flash Player installers, malicious online advertisements, social engineering, software 'cracks'.
Damage	Data and financial losses, loss of access to personal accounts, problems with browsing safety, online privacy issues.
Malware Removal (Windows)	To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Combo Cleaner. Download Combo Cleaner To use full-featured product, you have to purchase a license for Combo Cleaner. 7 days free trial available. Combo Cleaner is owned and operated by RCS LT, the parent company of PCRisk.com.

Mac malware examples

macOS.Macma and OceanLotus are a couple examples of programs similar to SysJoker. Theoretically, backdoor malware can infect devices with any type of malware. However, they may have certain limitations or be designed to inject specific programs into systems. UpdateAgent, Silver Sparrow, Tarmac, and OSAMiner are a few other Mac-specific malicious programs.

How did SysJoker infiltrate my computer?

Malware is spread using phishing and social engineering methods. To elaborate, spam campaigns are commonly used for this purpose. Spam emails can have malicious files attached to and/or linked inside them. Virulent files can be executables, archives, PDF and Microsoft Office documents, JavaScript, etc. Malicious software download/installation is jumpstarted - once these files are opened.

Malware is also proliferated through untrustworthy download channels, e.g., unofficial and free file-hosting websites, Peer-to-Peer (P2P) sharing networks, and other third-party downloaders.

Illegal activation ("cracking") tools and fake updates are used in distribution as well. "Cracks" can cause infections instead of activating licensed products. Fraudulent updaters infect systems by abusing outdated software weaknesses and/or by installing malicious programs.

How to avoid installation of malware?

The attachments and links found in suspicious and irrelevant emails - must not be opened, as they are potential sources of infection. It is advised to always download from official and verified sources. Additionally, all programs must be activated and updated with tools/functions provided by legitimate developers.

It is paramount to have a reputable anti-virus installed and kept updated. This software has to be used to run regular system scans and to remove detected threats. If your computer is already infected with malware, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate them.

Instant automatic 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 malware. Download it by clicking the button below:

DOWNLOAD Combo Cleaner

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. 7 days free trial available. Combo Cleaner is owned and operated by RCS LT, the parent company of PCRisk.com.

Quick menu:

What is "SysJoker"?
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:

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.

DOWNLOAD remover for malware infections

Combo Cleaner checks if your computer is infected with malware. To use full-featured product, you have to purchase a license for Combo Cleaner. 7 days free trial available. Combo Cleaner is owned and operated by RCS LT, the parent company of PCRisk.com.

Mac malware removal and recovery procedure

If unfamiliar processes are running, browser searches are being redirected, fans are spinning loudly for no reason, or fake "Update Safari" prompts have appeared, your Mac is likely infected. Run a full scan with Combo Cleaner for Mac to remove the infection. The full manual procedure below covers cases where automatic removal failed, where you want to verify a scan caught everything, or where the malware has multiple persistence points across LaunchAgents, LaunchDaemons, and Configuration Profiles.

Common Mac malware behaviors

VisibleAdware injection - browser hijackers and fake search engines

The most common Mac malware. Replaces your default search engine, homepage, or new-tab page with a lookalike domain that funnels every query through ad networks before passing it to a real provider. Often arrives bundled with cracked apps, fake Flash Player updates, or "free media player" downloads (MPlayerX, NicePlayer).

Browser showing redirected search results from a hijacked search engine

HiddenLaunchAgent / LaunchDaemon persistence

The standard way Mac malware survives reboots. A small .plist file in /Library/LaunchAgents/, /Library/LaunchDaemons/, or ~/Library/LaunchAgents/ tells launchd to run the malware at every login or boot. The .plist often picks a generic-looking name like com.apple.AdobeFlash.plist or com.system.helper.plist to blend in among legitimate Apple files.

Finder window showing suspicious .plist files in LaunchAgents folder

HiddenConfiguration Profile abuse

Configuration Profiles are an enterprise feature - they let an IT department enforce policy on managed Macs (homepage, DNS, certificates, password rules). Adware abuses this by silently installing a Profile that locks the browser homepage, default search, or DNS server at the OS level. Manual browser reset doesn't help - the Profile reapplies the hijack. Check System Settings → General → Device Management (or "Profiles" on older macOS).

VisibleFake update prompts (FlashPlayer.dmg variants)

"Your Flash Player is out of date" or "Update your browser to view this content." Adobe killed Flash in 2020 - any current "Flash update" prompt is malware. The Atomic macOS Stealer (AMOS) family heavily uses this trick to deliver info-stealers that grab browser passwords, keychain items, and crypto wallet seed phrases. Apple's Software Update never appears as a browser pop-up.

Browser showing fake Adobe Flash Player update prompt

SymptomCryptominer CPU usage

Fans spin loudly, the Mac runs hot, battery drains fast, Activity Monitor shows a process near 100% CPU. Cryptominers run silently in the background to mint cryptocurrency for the attacker. Often delivered via cracked apps from torrent sites, browser extensions, or supply-chain compromises in legitimate Mac software.

Activity Monitor showing a process consuming high CPU

HiddenInfo stealing - AMOS, Banshee, Cthulhu, RustDoor

Modern Mac stealer families - AMOS (Atomic macOS Stealer), Banshee, Cthulhu, and RustDoor are the most active - read browser-saved passwords, cookies, autofill data, the macOS Keychain, crypto wallet seed phrases (Exodus, Electrum, Trezor Suite, MetaMask, etc.), and Apple Notes. AMOS is the most prolific overall, distributed via fake software installers, cracked apps, and fake "Spotlight" or "ChatGPT" sites. Once data is exfiltrated, the malware often deletes itself, leaving little trace - which is why credential rotation in Step 10 is critical even after the infection appears gone.

Tools you'll need

Combo Cleaner for Mac 7-days free trial available

Recommended primary scanner. Detects adware, info-stealers, cryptominers, and the persistence files they install.

Activity Monitor Free · built-in

Built into macOS. Shows running processes with full file paths, CPU, memory, and network usage.

KnockKnock Free

By Objective-See (Patrick Wardle). Lists every place macOS malware can persist - LaunchAgents, LaunchDaemons, Login Items, Cron, Browser Extensions, Kernel Extensions, more.

Console.app Free · built-in

Built into macOS (Applications → Utilities). Shows system logs - useful for finding what process is launching a suspicious child.

Contain - limit the damage

~5 min

Disconnect from the network

⏱ 30 secNo tool needed

Click the Wi-Fi icon in the menu bar (or open Control Center) and turn Wi-Fi off. If you're on Ethernet, unplug the cable. This stops any active info-stealer or backdoor from sending data out or accepting commands. Keep the network off until you've booted into Safe Mode (next step) - you'll reconnect there briefly to download the scanner.

Why this mattersAMOS-family stealers exfiltrate browser passwords, keychain entries, and crypto wallet seeds within seconds of running. Cutting the network is the only way to stop ongoing exfiltration immediately.

Boot into Safe Mode and download Combo Cleaner

⏱ 5 min

macOS Safe Mode loads only Apple-trusted kernel extensions and skips most third-party LaunchAgents and user login items, so persistent Mac malware doesn't auto-run while you set up the scanner. Network access works normally in Safe Mode.

Apple Silicon (M1, M2, M3, M4)

Choose Apple menu → Shut Down
Wait until the Mac is fully off
Press and hold the Power button until "Loading startup options" appears
Select your startup disk (usually "Macintosh HD")
Hold Shift, then click Continue in Safe Mode
Log in - the menu bar will show "Safe Boot" in red

Intel-based Mac

Choose Apple menu → Restart
Immediately press and hold the Shift key as the Mac begins to boot
Release Shift when the login window appears
Log in - the menu bar will show "Safe Boot" in red

Once Safe Mode has loaded, turn Wi-Fi back on and download Combo Cleaner for Mac. Save the .dmg to your Desktop. You can disconnect Wi-Fi again before scanning if you want extra caution.

Identify - find what's hiding

~15 min

Inspect running processes with Activity Monitor

Tool: Activity Monitor⏱ 5 min

Open Activity Monitor (Applications → Utilities → Activity Monitor, or Cmd+Space and type "Activity Monitor"). Sort by CPU usage to spot cryptominers and runaway processes.

Click each unfamiliar process and choose View → Inspect Process (Cmd+I) to see:

Path - anything in /private/tmp/, ~/Library/Application Support/<random-name>/, or with a generic-looking bundle ID is suspicious
Code signing - Apple's processes are signed by "Apple" or "Software Signing." Adhoc-signed or unsigned binaries from third parties warrant investigation
Open Files and Ports - shows what the process is touching on disk and network

Why this mattersMac malware often picks process names like "CoreServicesAgent" or "WindowServer" that look legit at a glance. The Inspect view shows the actual file path, which is what tells you it's not Apple's.

Activity Monitor showing the Inspect Process panel for a suspicious process

Map persistence with KnockKnock and inspect the launch paths

Tool: KnockKnock + Finder⏱ 7 min

Download KnockKnock by Objective-See (Patrick Wardle's free tool, the Mac equivalent of Sysinternals Autoruns). It lists every place macOS malware can persist in a single window: LaunchAgents, LaunchDaemons, Login Items, Cron Jobs, Browser Extensions, Kernel Extensions, Authorization Plug-ins, Mail Plug-ins, Quicklook, Spotlight, and more.

Run KnockKnock and toggle "Filter Signed Items" to focus on unsigned or non-Apple-signed entries. Click any suspicious item to see its file path and code-signing status.

If you'd rather check manually, open Finder → Go → Go to Folder (Shift+Cmd+G) and visit each path:

/Library/LaunchAgents/ - system-wide, runs at login for any user
/Library/LaunchDaemons/ - system-wide, runs at boot before login
~/Library/LaunchAgents/ - user-level, runs at this user's login
~/Library/Application Support/ - where adware drops its data folder, often with a random or app-mimicking name

Then check additional persistence locations in System Settings:

Login Items & Extensions - System Settings → General → Login Items & Extensions. Click anything you don't recognize and remove it
Background Items - same panel, "Allow in the Background" section. Mac malware often shows up as a background item with an obscure name
Configuration Profiles - System Settings → General → Device Management (or "Profiles" on older macOS). Remove any Profile you didn't install yourself

Pro tipRight-click any suspicious .plist → Open With → TextEdit. The <key>Program</key> and <key>ProgramArguments</key> values tell you exactly what executable runs and from where. Don't delete yet - write down the file paths and entry names. We'll remove them after the Combo Cleaner scan in Step 7.

KnockKnock main window showing categorized persistence list

Check /etc/hosts and DNS settings

⏱ 3 minBuilt into macOS

Mac malware sometimes redirects bank, Apple, antivirus, and update domains to attacker-controlled servers via the hosts file or DNS settings.

Hosts file: Open Terminal (Applications → Utilities → Terminal) and run:

sudo nano /etc/hosts

Legitimate entries are commented with #. Any uncommented IP-to-domain mapping is suspicious - especially redirects for apple.com, icloud.com, your bank, or your password manager. Press Ctrl+X to exit nano without saving.

DNS settings: System Settings → Network → click your active connection (Wi-Fi or Ethernet) → Details → DNS. Confirm DNS servers point to your ISP, your router, or a known public resolver (Cloudflare 1.1.1.1, Google 8.8.8.8). Anything else has been hijacked.

Why this mattersA clean Mac with hijacked DNS is still a compromised Mac. You'll think you're at chase.com and you'll be at the attacker's clone.

Remove - scan and clean up

~30 min

Recommended antivirus: Combo Cleaner for MacDetects adware, info-stealers, cryptominers, and the LaunchAgent / LaunchDaemon persistence files they install. The 7-day free trial is available.

Download Combo Cleaner

Run a full Combo Cleaner for Mac scan

Tool: Combo Cleaner⏱ 20–30 min

Open the .dmg you downloaded in Step 2. Drag the Combo Cleaner icon to the Applications folder. Open it from Launchpad (or Applications), allow it to update its threat database, then click Start Combo Scan and let it complete fully. Review what it found and apply the recommended actions.

Why this comes before manual cleanupCombo Cleaner removes known adware, info-stealers, cryptominers, and the LaunchAgent persistence files they installed in one pass. Manual cleanup in Step 7 is for anything still left over.

Manually remove anything still present

⏱ 10 minTool: Finder

Reopen KnockKnock (or revisit the Finder paths from Step 4). Anything you flagged that's still present hasn't been caught by the automated scan. For each remaining suspicious entry:

Note the executable path the .plist references (right-click the .plist → Open With → TextEdit, look at <key>Program</key>)
Move the .plist to Trash
Move the executable file at the referenced path to Trash
Empty the Trash

Then go to /Applications and remove any unwanted apps the malware installed. Common adware-installed app names: MPlayerX, NicePlayer, MyShopcoupon, Advanced Mac Cleaner, Mac Cleanup Pro. Drag them to Trash, then check ~/Library/Application Support/ for any folder with the same name and delete it too.

ImportantSome malware files reappear after deletion because something else on the system recreates them. If a file returns within minutes, you have a remaining persistence point KnockKnock didn't show. Re-run Combo Cleaner or proceed to a macOS reinstall (see end of guide).

Recover - restore browsers and security

~15 min

Reset browsers and clear notification permissions

⏱ 5 min

Mac adware persists in browser extensions, search engine settings, homepage, and notification permissions. Reset each browser you use:

Safari: Safari → Settings → Extensions - uninstall anything you don't recognize. Then Safari → Settings → Search - restore your preferred default search engine. Then Safari → Settings → Websites → Notifications - remove all unfamiliar sites. For a deep reset: Safari → History → Clear History → "all history."
Chrome: visit chrome://settings/reset → "Restore settings to their original defaults." Then chrome://settings/content/notifications and remove unfamiliar sites.
Firefox: open about:support → Refresh Firefox. Then check Settings → Privacy & Security → Permissions → Notifications.

Review installed extensions in each browser and remove anything you don't recognize, especially extensions you didn't install yourself.

Re-verify Gatekeeper, FileVault, and System Integrity Protection

⏱ 10 min

Some Mac malware tries to weaken built-in security to make persistence easier. Verify each is on:

Gatekeeper (blocks unsigned apps): System Settings → Privacy & Security → scroll to Allow applications downloaded from → confirm "App Store and identified developers" is selected (not "Anywhere"). If the malware added itself to the allow-list, the entry appears in the same panel - remove it.
FileVault (full-disk encryption): System Settings → Privacy & Security → FileVault → confirm "FileVault is on for this disk." If it was disabled by malware, turn it back on.
System Integrity Protection (SIP): open Terminal and run csrutil status. Output should be "System Integrity Protection status: enabled." If disabled, you'll need to reboot into Recovery Mode and run csrutil enable from there.

Then run macOS Software Update (System Settings → General → Software Update) to apply the latest security patches.

Verify & secure

~15 min + 7 days

Change passwords from a clean device

⏱ 20 min⚠ critical for AMOS family

If the malware was an info-stealer (AMOS, Banshee, Cthulhu, or RustDoor families are extremely common on Mac), assume every password saved in your browser is compromised. So is your iCloud Keychain if it was unlocked while the malware ran. Change passwords from a different, known-clean device - your iPhone is fine if it's not infected.

Recommended order:

Apple ID first - it controls iCloud, Find My, Apple Pay, and the App Store
Primary email - the recovery hub for everything else
Banking and financial accounts
Password manager master password (if you use one)
Crypto wallet seed phrases - if you store any seed phrase or private key on the Mac, AMOS specifically targets these. Move funds to a fresh wallet from a clean device immediately, before changing other passwords
Social media, shopping, and remaining accounts

Where available, enable phishing-resistant multi-factor authentication (passkeys / hardware keys / authenticator apps) - SMS-based MFA is bypassable.

Verify the clean and monitor for 7 days

⏱ 5 min + 1 week monitoring

Reconnect to the network and run one final full scan with Combo Cleaner. Open System Settings → General → Login Items & Extensions and confirm nothing suspicious has reappeared. Open Activity Monitor and verify no unfamiliar process is using significant CPU.

Over the next 7 days, watch for symptom recurrence: high CPU when the Mac is idle, browser redirects returning, fake update prompts, or unfamiliar Login Items reappearing. If anything returns, you missed a persistence point and the procedure needs to be repeated - or you may have a deeper compromise that requires a clean macOS reinstall.

System Settings Login Items showing a clean list

When to reinstall macOS instead

Manual removal isn't always the right answer. Reinstalling macOS from scratch is the only way to be 100% certain when:

The malware reappears after every removal attempt
A kernel extension or system-level component was modified
Confirmed credential-theft malware ran with admin rights - the system likely has multiple unknown payloads
The Mac is used for online banking, crypto wallets, business email, or anything where partial doubt isn't acceptable

macOS reinstall is straightforward: shut down → boot to Recovery (Apple Silicon: hold the Power button → Options; Intel: Cmd+R during boot) → Erase Mac → Reinstall macOS. Back up documents to external storage first, scan the backup with Combo Cleaner before restoring it, and reinstall apps fresh - never restore them from a backup of the infected system.

Important: Manual removal of Mac malware requires care - deleting the wrong .plist or system app can prevent macOS from booting normally. If you're not confident identifying system files from malicious files, run an automated scan with Combo Cleaner for Mac and stop there - that path catches the vast majority of consumer Mac malware without the risk of breaking macOS.

Frequently Asked Questions (FAQ)

My computer is infected with SysJoker malware, should I format my storage device to get rid of it?

No, such drastic measures are not required for SysJoker's removal.

What are the biggest issues that SysJoker malware can cause?

What danger a piece of malicious software poses - depends on its features and the cyber criminals' modus operandi. SysJoker is designed to cause chain infections; hence, its infections can lead to diminished system performance, data loss, hardware damage, serious privacy issues, financial losses, and identity theft.

What is the purpose of SysJoker malware?

In nearly all cases, malware only aims to generate revenue at its victims' expense. Other potential reasons for the release of malicious programs include: political/geopolitical motivations, personal reasons (e.g., vendettas against certain individuals, etc.), disruption of specific processes (e.g., websites, services, companies, organizations, etc.), or simply the cyber criminals' amusement.

How did SysJoker malware infiltrate my computer?

Malicious software is distributed using phishing and social engineering. It is spread via drive-by (deceptive and stealthy) downloads, online scams, unofficial and freeware download sites, Peer-to-Peer sharing networks (Torrent clients, eMule, etc.), spam mail, illegal program activation tools ("cracks"), fake updates, and so forth. Some harmful programs are capable of self-proliferating through local networks and removable storage devices (e.g., external hard drives, USB flash drives, and similar).

Will Combo Cleaner protect me from malware?

Yes, Combo Cleaner can detect and eliminate most of the known malware infections. However, performing a full system scan is crucial - since sophisticated malicious programs tend to hide deep within systems.