How to eliminate KEYSTEAL trojan-type malware from the operating system

What is KEYSTEAL?

KEYSTEAL is the name of a trojan targeting macOS Keychain data. This malware arrives onto systems as a trojanized app called ResignTool. Due to how sensitive the information stored on the Mac Keychain can be - this malware poses significant threats to user privacy.

KEYSTEAL malware overview

The variant of KEYSTEAL that we analyzed was installed by a malicious installer claiming to carry the ResignTool application. Following installation, the malware retained this disguise. However, it is more than just a combination of the same app icon and name; it is a modified ("trojanized") version of ResignTool.

ResignTool is designed to change the signing information on IPA format archive files used on iOS. This application is free but not available on Apple's App Store. Therefore, this program can only be obtained from open-source project hosting and file-sharing platforms - which opens up an avenue for cyber criminals to trojanize ResignTool and proliferate its malicious versions.

KEYSTEAL malware targets Keychain information. The password management system of macOS called Keychain can store a variety of vulnerable data, including usernames/passwords, private keys, digital certificates, secure notes, and other sensitive information.

This trojan also obtains the user account password by displaying a pop-up requesting this information after its installation is completed.

It is noteworthy that once KEYSTEAL concludes its malicious activities, it runs ResignTool's original routine - thus covering its tracks.

To summarize, KEYSTEAL infections can result in severe privacy issues, financial losses, and even identity theft.

Mac malware examples

We have analyzed countless malware samples; GIMMICK, UpdateAgent, SysJoker, DazzleSpy, and NUKESPED are a few examples of those targeting mac Operating Systems.

Malicious software can have a wide variety of functionalities, and these functions can be in different combinations. However, regardless of whether a malicious program steals information, encrypts data, mines cryptocurrency, or performs other activities - its presence on a system endangers device integrity and user safety. Therefore, we strongly recommend eliminating all threats immediately upon detection.

How did KEYSTEAL infiltrate my computer?

Since KEYSTEAL infiltrates systems as a trojanized ResignTool application, it could be that its proliferation methods target users searching for this specific app to download. While ResignTool is free, it is unavailable on Apple's official store - hence, it can only be obtained from open-source project platforms, free file-hosting websites, freeware pages, and similar channels.

However, it is just as likely that using ResignTool is a handy way to lower user suspicion since their immediate searches for information on it would lead to a description of the legitimate software. Therefore, it could be that the KEYSTEAL trojan is spread using several techniques.

Generally, malware is proliferated by employing phishing and social engineering tactics. Virulent files can be in various formats (e.g., archives executables, documents, etc.) and infect devices when they are opened.

The most widely used malware distribution methods include: drive-by (stealthy/deceptive) downloads, dubious download sources (e.g., freeware and free file-hosting websites, Peer-to-Peer sharing networks, etc.), online scams, malicious attachments and links in spam emails/messages, malvertising, illegal software activation ("cracking") tools, and fake updates.

How to avoid installation of malware?

We highly recommend downloading only from official and verified sources. It is just as important to activate and update software with legitimate tools, as illegal activation tools ("cracks") and third-party updaters can contain malware.

We advise caution when browsing since fraudulent and dangerous online content usually appears legitimate and harmless. Another recommendation is to be vigilant with incoming emails, DMs/PMs, and other messages. The attachments and links found in suspect/irrelevant mail must not be opened, as they can be malicious and cause infections.

We must emphasize the importance of having a reputable anti-virus installed and kept updated. Security programs must be used to perform regular system scans and to remove threats and issues. If your computer is already infected, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate threats.

KEYSTEAL trojan installation setup:

Pop-up (targeting user passwords) displayed after KEYSTEAL trojan's installation:

Appearance of KEYSTEAL trojan disguised as the ResignTool application:

Update 17 January 2024: The infostealers targeting macOS, namely KEYSTEAL, Atomic, and JaskaGo, underscore the persistent and adaptive nature of cybersecurity threats. Despite Apple's proactive measures, these malware variants exhibit continuous evolution, employing tactics such as code signature alterations, distribution method changes, and shifts in malicious behavior.

The threat landscape is characterized by the ability of these infostealers to evade static signature detection engines, emphasizing the importance of dynamic and advanced threat hunting techniques.

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:

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 "KEYSTEAL"?
• 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 KEYSTEAL malware using Combo Cleaner:

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.

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).

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.

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.

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.

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

1

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.

2

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)

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

Intel-based Mac

1. Choose Apple menu → Restart
2. Immediately press and hold the Shift key as the Mac begins to boot
3. Release Shift when the login window appears
4. 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

3

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.

4

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.

5

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

6

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.

7

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:

1. Note the executable path the .plist references (right-click the .plist → Open With → TextEdit, look at <key>Program</key>)
2. Move the .plist to Trash
3. Move the executable file at the referenced path to Trash
4. 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

8

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.

9

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

10

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:

1. Apple ID first - it controls iCloud, Find My, Apple Pay, and the App Store
2. Primary email - the recovery hub for everything else
3. Banking and financial accounts
4. Password manager master password (if you use one)
5. 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
6. Social media, shopping, and remaining accounts

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

11

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.

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 KEYSTEAL malware, should I format my storage device to get rid of it?

No, KEYSTEAL's removal does not necessitate formatting.

What are the biggest issues that KEYSTEAL malware can cause?

The threats posed by an infection depend on the malicious program's functionalities and the cyber criminals' aims. KEYSTEAL targets macOS Keychain data (e.g., passwords, private keys, certificates, etc.) - hence, these infections may result in severe privacy issues, financial losses, and even identity theft.

What is the purpose of KEYSTEAL malware?

While malware operates differently, it is mainly used to generate revenue. However, cyber criminals might also use this software for their own amusement or to carry out personal vendettas, disrupt processes (e.g., websites, services, etc.), and even launch politically/geopolitically motivated attacks.

How did KEYSTEAL malware infiltrate my computer?

Malware is most commonly proliferated through drive-by downloads, spam emails and messages, online scams, untrustworthy download sources (e.g., freeware and free file-hosting websites, Peer-to-Peer sharing networks, etc.), illegal software activation tools ("cracks"), fake updates, and malvertising. Some malicious programs are even capable of self-spreading via local networks and removable storage devices (e.g., USB flash drives, external hard drives, etc.).

Will Combo Cleaner protect me from malware?

Yes, Combo Cleaner is designed to detect and remove threats. It is capable of eliminating practically all known malware infections. Keep in mind that sophisticated malicious software typically hides deep within systems - therefore, running a full system scan is paramount for its detection.