How to remove NanoCore RAT

What is NanoCore?

NanoCore is high-risk trojan, a remote access tool (RAT). In most cases, this malware is proliferated using spam email campaigns. Criminals send thousands of deceptive emails that contain malicious attachments. Once opened, these files immediately infect computers with viruses such as NanoCore.

The presence of this malware can cause serious issues, since the malware distributor gains remote access to the infected system.

NanoCore in detail

NanoCore's license is sold on the dark web. Therefore, any aspiring cyber criminal can purchase and start distributing this malware. As mentioned above, this malware is mostly distributed using spam email campaigns. Cyber criminals send deceptive emails that deliver many different messages.

Some state that users must pay taxes, whilst others claim that they have received packages, and so on. Ultimately, all encourage users to open attached files, which might be MS Office document, executable images, archives, or similar. Opening them leads to infiltration of viruses such as NanoCore. Note that NanoCore is a remote access tool (RAT).

Therefore, the 'threat actor' (person or third party that distributes this malware) can remotely control the infected system. Furthermore, this malware is modular and, thus, its functionality can be expanded and configured by anyone.

Cyber criminals typically use RATs for injection of other viruses, performing dubious tasks, and stealing information (saved logins/passwords, etc.). For instance, remote access tools can be used to infiltrate ransomware, information-tracking trojans, and other similar malware. The system might also be used for tasks such as botnet attacks, crypto-mining, and so on.

Therefore, having a RAT installed on your computer can lead to various problems such as significant financial/data losses, privacy issues, hardware damage, reduced system performance, etc.

If you have recently opened dubious email attachments and suspect that NanoCore is present, immediately scan the system with a reputable anti-virus/anti-spyware suite and eliminate all detected threats.

More about malicious software

Many viruses are proliferated using spam campaigns including, for example, Nymaim, Ursnif, Hancitor, Adwind, and FormBook. These viruses are developed by different cyber criminals and their behavior might differ slightly (some provide developers with remote access, others open "backdoors" or record information, and so on).

Nevertheless, they all pose a significant threat to your privacy, financial security, and computer safety. Eliminate these threats immediately.

How did NanoCore infiltrate my computer?

As mentioned above, NanoCore is mostly distributed using spam email campaigns. Cyber criminals send email messages that contain malicious attachments.

The type of attachment can vary (some are MS Office documents, other are archives, executables, and so on), however, they are designed to trick users into opening the files, since only the user can trigger the infection in this way.

If malicious attachments are not opened by the user, the malware (in this case, NanoCore) cannot infiltrate the system. Therefore, the main reasons for these infections are poor knowledge of these threats and careless behavior.

How to avoid installation of malware?

The key to computer safety is caution. Therefore, pay attention when browsing the internet and downloading/installing software. Carefully analyze each email attachment received. If the file/link seems irrelevant or the sender seem suspicious/unrecognizable, do not open anything.

Have a reputable anti-virus/anti-spyware suite installed and running, since these tools can detect and eliminate malware before any damage is done. 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.

Screenshot of NanoCore process ("Default Document Handler (32 bit)") in Windows Task Manager (note that the process name might differ depending on the distributed malicious attachment):

Update August 26th, 2019 - NanoCore's developers have been offering this RAT as a service for as low as $25. Therefore, any wannabe cyber criminal could've bought and start spreading this malware. However, throughout its development, NanoCore's source code has been leaked and now it is available for free.

For this reason, there's a high credibility that the number of NanoCore's infections will significantly increase. We highly recommend to always have your installed Internet security suite updated and running - it will help you protect yourself from such infections.

Screenshot of a malicious Microsoft Excel document ("CoronaVirus.xlsm") used to spread NanoCore RAT:

Screenshot of a Japanese DHL-themed spam email used to spread NanoCore RAT (the malicious attachment is a .iso file - "DHL收据8897209547,pdf.iso"):

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

NanoCore can be eliminated without formatting the storage device. It can be removed by following the steps described in the removal guide above.

What are the biggest issues that malware can cause?

Depending on the type of malware, it can be used to encrypt (or steal) files, hijack online accounts, steal identities and (or) money, distribute other malware.

What is the purpose of NanoCore RAT?

In most cases, threat actors use RATs like NanoCore to drop additional payload (infect computers with ransomware, cryptominers, and other malware), steal sensitive information (for example, saved logins/passwords, credit card details), access files, execute commands.

How did a malware infiltrate my computer?

Most cybercriminals distribute malware using malicious spam, fake system warning messages, and other phishing, social engineering techniques. Also, they use drive-by downloads, Peer-to-Peer (P2P) networks, download pages for cracked software. It is known that NanoCore is distributed using malicious emails (malicious attachments) disguised as letters from legitimate entities.

Will Combo Cleaner protect me from malware?

Yes, Combo Cleaner can detect and eliminate almost all known malicious software. Pretty often, malware hides deep in the operating system to avoid detection. In such cases, computers must be scanned fully (using the full scan).