How to eliminate MerkSpy spyware from the operating system

What kind of malware is MerkSpy?

MerkSpy is a malicious program classed as spyware. This malware is designed to record and steal vulnerable information. MerkSpy spyware has been observed infiltrating systems via a Microsoft Office vulnerability tracked as "CVE-2021-40444".

MerkSpy malware overview

MerkSpy can infiltrate devices in a multi-stage process. One of the known chains began with a malicious Microsoft Word document. Typically, virulent MS Office files rely on users enabling macro commands (i.e., editing/content) to initiate infection processes.

However, the document intended to infiltrate MerkSpy – leverages the CVE-2021-40444 vulnerability. It exploits the MSHTML (Trident) component utilized by Internet Explorer in Microsoft Office to execute remote code. Hence, the necessity of additional user interaction (aside from opening the malicious file) is eliminated.

The chain then progresses through the download of other virulent files, execution script execution, and decryption processes (for encryption used as an anti-detection mechanism). The final payload – MerkSpy – arrives onto systems in a file disguised as a "GoogleUpdate". Note that this spyware could rely on other techniques to infiltrate systems.

Once established on a device, MerkSpy ensures persistence by setting itself to start automatically upon each system reboot. The malware collects relevant device data. It also has the ability to take screenshots, which enables attackers to obtain all sorts of data visible on victims' screens.

MerkSpy has keylogging capabilities as well. In other words, this program can record keystrokes (keyboard input). Therefore, cyber criminals can also acquire information that is rendered invisible on screens, such as passwords and passphrases.

Additionally, MerkSpy can extract log-in credentials (usernames/passwords) stored in Google Chrome browsers. This program seeks data from the MetaMask cryptowallet browser extension.

Keep in mind that malware developers often improve upon their creations and methodologies. Hence, potential future iterations of MerkSpy could boast additional/different functionalities and features.

To summarize, the presence of software like MerkSpy on devices can lead to severe privacy issues, financial losses, and identity theft.

Examples of malware with spyware traits

We have written about countless malicious programs; Ghostly, Mia Khalifa Game, Evil Extractor, and Raccoon Stealer are just some examples of ones that possess spyware capabilities.

Features for recording and stealing victims' information are incredibly prevalent in various types of malware – they are not exclusive to spyware and stealers.

However, regardless of how malicious software functions – its presence on a system threatens device and user safety. Therefore, all threats must be removed immediately upon detection.

How did MerkSpy infiltrate my computer?

MerkSpy has been noted infiltrating systems via malicious Microsoft Word files disguised as documents detailing a job position for a software developer or a trading journal (other lures are possible). The infectious documents rely on the previously described Microsoft Office vulnerability tracked as "CVE-2021-40444".

This MS vulnerability allows attackers to execute remote code via MSHTML (Trident) component, which is used by Internet Explorer in Microsoft Office. The infection chain is triggered after the document is opened rather than after a user enables macros (i.e., editing/content) – as is standard for virulent Microsoft Office files.

The malicious document includes a hidden URL used to download an HTML file. It includes shellcode that functions as a downloader, the final goal of which is to download, decrypt, and execute MerkSpy under the guise of a "GoogleUpdate". It must be mentioned that this spyware could infiltrate devices by relying on different methods.

Generally, malware is proliferated using phishing and social engineering tactics. It is commonly presented as or bundled with ordinary content. Aside from various document formats (Microsoft Office, Microsoft OneNote, PDF, etc.), malware can arrive onto systems in archives (ZIP, RAR, etc.), executables (.exe, .run, etc.), JavaScript, and so forth.

The most prevalent distribution techniques include: drive-by (stealthy/deceptive) downloads, malicious attachments/links in spam mail (e.g., emails, PMs/DMs, SMSes, etc.), online scams, malvertising, untrustworthy download channels (e.g., freeware and free file-hosting sites, P2P sharing networks, etc.), illegal software activation tools ("cracks"), and fake updates.

Malware may also be capable of self-spreading via local networks and removable storage devices (e.g., external hard drives, USB flash drives, etc.).

How to avoid installation of malware?

We highly recommend downloading only from official and verified sources. Additionally, all programs must be activated using functions/tools provided by genuine developers. The same applies to updating software and eliminating its vulnerabilities, as updaters acquired from third-parties can contain malware.

Another recommendation is to be vigilant when browsing since fraudulent and malicious online content usually appears legitimate and harmless. Incoming emails and other messages must be approached with caution. Attachments or links in suspicious mail must not be opened, as they can be infectious.

We must stress the importance of having a dependable anti-virus installed and kept up-to-date. Security programs must be used to run regular system scans and to remove detected threats. If you believe that your computer is already infected, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate infiltrated malware.

Screenshots of malicious Word documents used to proliferate MerkSpy:

How to remove malware manually?

Most trojan infections can be removed by running a full system scan with Combo Cleaner. The full manual procedure below is for cases where automatic removal failed, where you want to verify a scan caught everything, or where the threat has multiple persistence points.

Tools you'll need

Combo Cleaner Antivirus 7-days free trial

Recommended primary scanner. VB100 certified. The 7-day free trial is available.

Microsoft Defender Offline Free · built-in

Built into Windows. Boots to a clean environment to catch rootkits.

Process Explorer Free

From Microsoft Sysinternals. Better than Task Manager - shows full paths and signatures.

Autoruns Free

From Microsoft Sysinternals. Lists every place malware can persist on your system.

Microsoft Safety Scanner (MSERT) Free

Official Microsoft on-demand scanner. Always-current signatures - expires every 10 days.

Phase 1~ 5 min

Contain - limit the damage

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1

Disconnect from the network

30 secNo tool needed

Unplug your Ethernet cable and turn off Wi-Fi. If you're on a laptop, the airplane-mode key works fastest.

Why this matters

Many trojans exfiltrate data - saved browser passwords, banking sessions, screenshots - and accept remote commands. Cutting the network stops both immediately. Keep it disconnected until Phase 4.

2

Boot into Safe Mode with Networking

3 min

Safe Mode loads a minimal set of drivers and stops most malware from auto-running. "With Networking" lets you download tools - re-enable Wi-Fi only after you've booted in.

Windows 11

Open Settings → System → Recovery. Click Restart now next to Advanced startup.

Your computer will restart into the "Choose an option" menu. Click Troubleshoot → Advanced options → Startup Settings → Restart. After the second reboot, press 5 or F5.

Windows 10

Click the Windows logo, hold Shift, click the Power icon and choose Restart. In the Choose an option screen, click Troubleshoot → Advanced options → Startup Settings → Restart. Press F5.

Windows 8

Go to the Start Screen, type Advanced, select Settings → Advanced startup options → Restart now → Troubleshoot → Advanced options → Startup settings → Restart → F5.

Note: Windows 8 reached end-of-life in January 2023 - running on it puts you at much higher risk of reinfection.

Windows 7

Click Start → Shut Down → Restart → OK. As the system boots, press F8 repeatedly until the Windows Advanced Options menu appears, then choose Safe Mode with Networking.

Note: Windows 7 reached end-of-life in January 2020 - running on it puts you at much higher risk of reinfection.

Phase 2~ 15 min

Identify - find what's hiding

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3

Inspect running processes with Process Explorer

Tool: Process Explorer5 min

Download Process Explorer from Microsoft Sysinternals. Run it as Administrator. Click Options → Verify Image Signatures and View → Lower Pane View → DLLs.

Sort by "Verified Signer." Anything unsigned running from %AppData%, %LocalAppData%, %Temp%, or %ProgramData% is suspicious. Right-click → Properties to see the full image path. Right-click → "Search Online" to look up unfamiliar process names.

Why not just Task Manager

Task Manager hides full file paths, doesn't show digital signatures, and groups processes in ways that make malware easy to miss. Process Explorer is the same tool Microsoft engineers use.

4

Map every persistence point with Autoruns

Tool: Autoruns 14.x10 min

Download Autoruns. Right-click Autoruns.exe and choose Run as administrator - without elevation, Autoruns can't inspect protected registry hives.

In the menu, open Options → Hide Microsoft Entries and Options → Hide Empty Locations, then click Refresh.

Modern trojans don't just live in startup. Walk through these tabs and look for unsigned or unfamiliar entries:

• Logon - classic Run/RunOnce keys
• Scheduled Tasks - frequent hiding spot, especially tasks with PowerShell, MSHTA, or rundll32 actions
• Services - unsigned services in non-Microsoft folders
• WMI - Event Subscriptions are a stealthy persistence mechanism (MITRE T1546.003)
• Image Hijacks - Image File Execution Options "Debugger" abuse
• AppInit - DLLs loaded into every GUI process
• Browser plug-ins - unsigned add-ons across all installed browsers

Pro tip

Right-click any suspicious entry → "Jump to Image" to see the actual file. Right-click → "Search Online" opens VirusTotal for the file hash. Don't delete yet - just write down the file paths and entry names. We'll remove them after the scans.

5

Check the hosts file and DNS settings

3 minBuilt into Windows

Trojans often redirect bank, antivirus, and update domains to attacker-controlled servers by editing the hosts file or DNS settings.

Hosts file: Open Notepad as Administrator and open C:\Windows\System32\drivers\etc\hosts. Legitimate entries are commented with #. Any uncommented IP-to-domain mapping is suspicious - especially redirects for microsoft.com, windowsupdate, or your bank.

DNS settings: Open Command Prompt as Administrator and run ipconfig /all. Confirm your DNS servers point to your ISP, your router, or a known public resolver (Cloudflare 1.1.1.1, Google 8.8.8.8). Then open Settings → Network & internet → [your adapter] → DNS server assignment and verify both DNS and DNS over HTTPS (DoH) settings haven't been hijacked.

Why this matters

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

Phase 3~ 60-90 min

Remove - three scans, one cleanup

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No single antivirus catches everything. The order below is intentional: offline scan first (catches rootkits before Windows fully loads), then on-demand scanners on the running system, then manual cleanup of anything they missed.

6

Run Microsoft Defender Offline

Tool: Built into Windows15 min

Reboot to normal Windows. Open Windows Security → Virus & threat protection → Scan options. Select Microsoft Defender Antivirus (offline scan) and click Scan now. Your computer will restart into a stripped-down environment and scan before the full operating system loads.

Why this comes first

Rootkits and bootkits hide from any scanner running on the same Windows session that's already infected. A pre-boot offline scan sees the disk before the malware can hide itself.

Recommended antivirus

Combo Cleaner

VB100 certified. Includes anti-trojan, registry/persistence scanning, anti-spyware in one pass. The 7-day free trial is available.

Download Combo Cleaner

7

Run Combo Cleaner full system scan

Tool: Combo Cleaner20-40 min

Install Combo Cleaner and run a full system scan (not the quick scan). Let it complete fully, review the detected threats, and apply the recommended actions. Combo Cleaner will quarantine known trojans and registry persistence.

8

Run Microsoft Safety Scanner as a second-opinion scan

Tool: Microsoft Safety Scanner15 min

Download Microsoft Safety Scanner (MSERT.exe), Microsoft's free on-demand tool. The binary expires every 10 days, which means every download has the latest signatures. Run a full scan after Combo Cleaner to catch anything one engine alone might miss.

Why a second scan

Different scanning engines catch different threats. Running an additional Microsoft scan after Combo Cleaner is the single most underused verification step in malware removal.

9

Manually remove anything still listed in Autoruns

Tool: Autoruns10 min

Reopen Autoruns. Anything you flagged in Step 4 that's still present hasn't been caught by the automated scans. For each remaining suspicious entry: right-click → Delete in Autoruns (this removes the persistence registration), then navigate to the file path and delete the actual file. Empty the Recycle Bin.

Important

Some malware files reappear after deletion because something else on the system recreates them. If you delete a file and it returns within minutes, you have a remaining persistence point that Autoruns didn't show - usually a service or scheduled task running under SYSTEM. Re-run the scans from Steps 6-8 or proceed to a clean install (see end of guide).

Phase 4~ 15 min

Recover - restore browsers and security

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10

Reset browsers and clear notification permissions

5 min

Trojans and adware frequently hijack browsers - change the default search engine, install rogue extensions, or grant themselves notification permissions to keep displaying scam pop-ups even after the malware is gone.

• Chrome: visit chrome://settings/reset and click "Restore settings to their original defaults." Then visit chrome://settings/content/notifications and remove any unfamiliar sites.
• Edge: visit edge://settings/reset. Then check edge://settings/content/notifications.
• Firefox: open about:support and click Refresh Firefox (Firefox uses "Refresh," not "Reset"). 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.

11

Re-enable Defender, Tamper Protection, and update everything

10 min

Many trojans disable security software. Open Windows Security → Virus & threat protection → Manage settings and confirm Real-time protection, Cloud-delivered protection, and Tamper Protection are all turned on. Tamper Protection prevents malware from disabling Defender silently.

Then run Windows Update (Settings → Windows Update → Check for updates) and update your browsers and applications. The infection vector that let the trojan in originally usually involves outdated software.

Phase 5~ 15 min + 7 days

Verify & secure

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12

Change passwords from a clean device

20 min⚠ Critical

If the trojan was an info-stealer (Lumma, RedLine, Vidar, and similar are extremely common), assume every password saved in your browser is compromised. Change them from a different, known-clean device - your phone is fine if it's not infected.

Recommended order:

1. Primary email first - it's the recovery hub for everything else
2. Banking and financial accounts
3. Password manager master password (if you use one)
4. Social media, shopping, and remaining accounts

Where available, enable phishing-resistant multi-factor authentication (passkeys / FIDO2 hardware keys / authenticator apps) - SMS-based MFA is bypassable by sophisticated attackers.

13

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 Task Manager (Ctrl + Shift + Esc) and switch to the Startup apps tab - confirm nothing suspicious has reappeared.

Over the next 7 days, watch for symptom recurrence: unexpected high CPU usage, unknown processes returning, browser redirects, or pop-ups. 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 install.

When to clean install Windows instead

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

• The malware reappears after every removal attempt
• A bootkit or UEFI rootkit was detected (this class of threat sits below the operating system and survives a normal Windows reinstall)
• A confirmed credential-theft trojan ran with administrator privileges (Lumma, RedLine, Vidar) - the system likely has multiple unknown payloads
• The PC is used for online banking, business email, or anything where partial doubt isn't acceptable

A clean install is a 30-60 minute process: Windows 11 reinstall via Settings → System → Recovery → Reset this PC → Remove everything → Cloud download. Back up documents to external storage first, scan the backup with Combo Cleaner before restoring it, and reinstall applications fresh - never restore them from a backup of the infected system.

Important: Manual removal requires advanced computer skills. If you're not confident identifying system files from malicious files, run an automated scan with Combo Cleaner and Windows Defender and stop there - that path catches the vast majority of consumer trojans without the risk of breaking Windows by deleting the wrong file.

Frequently Asked Questions (FAQ)

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

No, malware removal rarely requires formatting.

What are the biggest issues that MerkSpy malware can cause?

The dangers posed by an infection depend on the malicious program's functionalities and the attackers' aims. MerkSpy is a spyware that records and steals sensitive data. Generally, infections of this kind can lead to severe privacy issues, financial losses, and identity theft.

What is the purpose of MerkSpy malware?

Malware is primarily used for financial gain. However, attacks can also be motivated by cyber criminals' amusement or personal grudges, process disruption (e.g., sites, services, companies, etc.), and political/geopolitical reasons.

How did MerkSpy malware infiltrate my computer?

MerkSpy has been observed infiltrating devices via malicious Microsoft Word documents leveraging the "CVE-2021-40444" vulnerability. Other techniques are not unlikely.

Malware is primarily spread through drive-by downloads, spam emails/messages, online scams, dubious download sources (e.g., unofficial and free file-hosting sites, P2P sharing networks, etc.), illegal software activation tools ("cracks"), fake updates, and malvertising. What is more, some malicious programs can self-proliferate via local networks and removable storage devices.

Will Combo Cleaner protect me from malware?

Yes, Combo Cleaner is capable of detecting and eliminating nearly all known malware infections. Remember that sophisticated malicious programs tend to hide deep within systems – hence, running a full system scan is paramount.