DUNIHI Virus

What is DUNIHI?

DUNIHI (also known as Houdini) is high-risk virus designed to infiltrate the system, modify registry settings, and continually self-distribute itself by infiltrating removable drives. This malware allows cyber criminals to perform various actions remotely. Therefore, infiltrated systems are at very high risk.

Cyber criminals use spam email campaigns to spread this virus. They send hundreds of thousands of emails hoping that a percentage of users will open the malicious attachment, which will result in infiltration of DUNIHI.

One of the main DUNIHI features is to proliferate itself via removable drives. It infiltrates various storage devices (e.g., external hard drives, USB Flash drives, etc.) and creates a number of .lnk files (shortcuts) for each existing file and folder on the infiltrated, removable drive.

DUNIHI creates these shortcuts, since users are likely to execute them rather than opening the file/folder directly. Executing the shortcut leads to infiltration of DUNIHI. Since users of removable drives are likely to share them with other people or use them on multiple computers, this distribution method is very effective.

Furthermore, DUNIHI allows cyber criminals to perform various actions on the infected system. This is achieved by DUNIHI connecting to a remote Command and Control (C&C) server and receiving commands. The list of possible actions includes downloading/executing files, uploading files to the server, deleting files, and many others.

Thus, DUNIHI poses a significant threat to your privacy and computer safety: cyber criminals can download and install additional viruses and steal data. They can inject the system with ransomware (which encrypts data) or other high-risk viruses (that record private information, such as keystrokes, logins/passwords, etc.).

Therefore, the presence of DUNIHI might lead to financial/data loss and even identity theft. Fortunately, DUNIHI leaves a number of traces and thus it is possible to detect this malware manually. It creates a number of copies of itself and places them in various system folders (a list of copies).

Furthermore, it creates several entries in the Windows Registry (a list of created entries). Therefore, if you find any of these entries, you must delete them immediately and scan the system with a reputable anti-virus/anti-spyware suite such as Combo Cleaner Antivirus for Windows.

In fact, if you have even the slightest suspicion that your system is infected, you should scan it anyway. The key to computer safety is caution.

There are many high-risk trojans similar to DUNIHI including Hancitor, TrickBot, and AZORult. These are just some examples. As these viruses are developed by different cyber criminals, their behavior might also differ slightly (some inject systems with malware, other steal personal information, and so on).

Regardless, they all pose a significant threat to your privacy and computer safety. Eliminate this malware immediately.

How did DUNIHI infiltrate my computer?

Cyber criminals proliferate DUNIHI using spam email campaigns. Typically, these emails are delivered with links to Google Docs disguised as PDF documents. The Google Docs link leads to a script file (usually .PIF, .VBS or .SCR) that, once executed, infects the system.

These viruses are also distributed using trojans, third party software download sources, and fake software update tools. Trojans cause chain infections, since they infiltrate computers and immediately start downloading other malware onto the system.

Third party download sources (peer-to-peer [P2P] networks, third party software download sources, free file hosting sites, etc.) proliferate viruses by presenting them as legitimate applications. Users are tricked into downloading and installing malware.

Fake software updaters infect computers by exploiting outdated software bugs/flaws or simply downloading and installing malware rather than promised updates/fixes. Note that lack of knowledge of these threats and careless behavior are the main reasons for computer infections - many users download and open files without understanding the possible consequences.

How to avoid installation of malware?

The key to computer safety is caution. Therefore, pay close attention when browsing the internet, and downloading, installing, and updating software. Never open files/links attached to an email that seems irrelevant or is received from a suspicious/unrecognizable email address.

Use only legitimate software and download it from official sources using direct download links (not third party downloaders/installers). Keep installed applications updated, however, to achieve this, use  implemented functions or tools provided by the official developer.

Having a reputable anti-virus/anti-spyware suite is also essential, since this software can detect and eliminate malware before it does any harm. 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.

List of folders that DUNIHI delivers copies to (depending on the DUNIHI variant, the list and location of copies might differ slightly):

• {drive letter}:\[virus_filename].vbs
• %Application Data%\[virus_filename].vbs
• %User Temp%\[virus_filename].vbs
• %User Startup%\[virus_filename].vbs

Screenshot of files created by the DUNIHI variant we analyzed:

List of registry entries created by DUNIHI (depending on the DUNIHI variant, the list and location of entries might differ slightly):

• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\[virus_filename]
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\[virus_filename]
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\[virus_filename]
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\[virus_filename]
• HKEY_LOCAL_MACHINE\SOFTWARE\[virus_filename]

Screenshots of Windows Registry entries created by the DUNIHI variant we analyzed:

List of commands that DUNIHI is capable of receiving from Command and Control (C&C) server:

• cmd-shell - Executes a "cmd.exe /c [command received from C&C server]" and sends the result back to the server.
• delete - Deletes a specified file.
• enum-driver - Generates a list of all existing drives, as well as their types and sends this information to the Command and Control server.
• enum-faf - Uploads all files and subfolders from a specified directory to the Command and Control server.
• enum-process - Sends the list of running processes to the Command and Control server.
• execute - Executes code received from the Command and Control server.
• exit-process - Terminates a specified process.
• recvr - Uploads a specified file to the Command and Control server.
• send - Downloads and runs a file from a URL that is specified by the Command and Control server. The file is named exactly how it appears in the URL and it is placed in a directory that it is also specified by the server. If the directory does not exist, DUNIHI uses the installation directory that is specified in its configuration.
• site-send - Downloads and runs a file from a URL that is specified by the Command and Control server. The filename is also specified by the server and the file is saved in the installation directory that is specified in DUNIHI configuration.
• sleep - Sleeps (suspends itself) for a specified period of time.
• uninstall - Removes itself from the system and all removable drives.
• update - Updates itself.

Screenshot of DUNIHI processes ("Microsoft ® Windows Based Script Host") in Windows Task Manager (note that the process name is generic and it appears whenever a script file such as .VBS is running):

Example of a fake Western Union transaction document used to inject DUNIHI virus into the system:

Text presented within this document:

The Following transaction is held for compliance. Please review and correct the following to complete the transaction.

1.  Date    Reason
   345 789 ****    03-06-2020    Additional Documents Required

View Full Details

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.