How to uninatall ZLoader malware from the operating system

What is ZLoader?

ZLoader (also known as DELoader and Terdot) is a malicious program distributed through malicious web pages that display a fake error notification (e.g., "The 'Roboto Condensed' font was not found").

Research shows that ZLoader infects systems with another malicious program, a banking Trojan called Zeus. We strongly advise against opening files downloaded from web pages that display this error message, or similar.

ZLoader overview

When the malicious website is visited, it displays an error message stating that the web page cannot be loaded properly due to a missing font called "Roboto Condensed". It encourages visitors to fix this error by downloading and installing the font through "Mozilla Font Pack" or "Chrome Font Pack" (depending on which browser was used to open the malicious page).

Depending on the browser, the page downloads "Chrome_Font.zip" or "Mozilla_Font.zip", which contain the "Chrome_Font.js" or "Mozilla_Font.js" JavaScript files respectively - these download and install ZLoader (a.k.a. DELoader and Terdot).

As mentioned, this malware is used to distribute Zeus, a banking Trojan capable of recording keystrokes and stealing online banking credentials such as logins, passwords. Typically, cyber criminals misuse this information to steal banking accounts and make fraudulent transactions, purchases, and so on.

Victims will then experience financial loss. Unfortunately, websites that display "The 'Roboto Condensed' font was not found" error can be used to proliferate other malicious programs like Nymaim, Ursnif as well.

Typically, websites that display fake virus, error and other warnings are opened through other untrustworthy websites, deceptive ads or unwanted apps that are installed on the browser and/or operating system. If you believe your computer is infected with ZLoader or other malware, eliminate it immediately.

Similar malware

More examples of malicious programs that are designed to steal sensitive information (including banking credentials) include Mispadu, Bolik and Casbaneiro.

Typically, they are distributed by disguising them as legitimate programs or files. When installed, however, they can cause serious problems such as installation of other malware, financial and data loss, problems with browsing safety, online privacy, and so on.

How did ZLoader infiltrate my computer?

As mentioned, cyber criminals proliferate ZLoader through a malicious web page that tricks people into downloading and opening a file (font), which will supposedly allow them to browse the page further.

Cyber criminals often proliferate malware through untrustworthy web pages, third party downloaders, free file hosting pages, Peet-to-Peer networks (e.g., torrent client, eMule) and other dubious file or software download channels/tools.

They also distribute malicious programs through spam campaigns, Trojans, fake software updaters and software 'cracking' (activation) tools. Using spam campaigns, they send emails that contain malicious attachments or website links that download malicious files.

They attach executables (.exe), PDF documents, archive files such as ZIP, RAR, Microsoft Office document or JavaScript files. If recipients open the attachments, they cause installation of malicious programs. Trojans are malicious programs that cause chain infections - once installed, they install additional malware.

Fake software updating tools usually infect systems by installing malware rather than updates/fixes or by exploiting bugs/flaws of installed software that is out of date.

Software 'cracking' tools supposedly bypass activation of paid, licensed software, however, cyber criminals use them to infect computers with malware. People who use 'cracks' thus risk installing malicious software onto the operating system.

How to avoid installation of malware

Software and files should not be downloaded through third party downloaders, Peer-to-Peer networks or the other tools mentioned above. Use only official, trustworthy websites and direct download links. Attachments or web links within irrelevant emails and received from unknown, suspicious addresses should not be opened.

Keep installed software up do date using tools provided by official software developers. Avoid third party updaters. The same applies to activation of licensed software - it is illegal to use 'cracking' tools to activate software. Keep operating systems safe by regularly scanning them for threats with reputable antivirus or anti-spyware software.

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 a pop-up on the "The 'Roboto Condensed' font was not found" scam web page (Mozilla Firefox):

Screenshot of a second pop-up on this page:

Screenshot of the first pop-up on the same scam page (Google Chrome):

Screenshot of the second pop-up on this scam page:

Examples of malicious Microsoft Word documents designed to spread ZLoader malware:

Examples of malicious Microsoft Excel documents designed to spread ZLoader malware:

A porn website (pornislife[.]online) promoting ZLoader malware as Java plug-in:

Example of a spam email used to spread ZLoader malware via attached malicious MS Excel document:

Text presented within:

Subject: Contract data#211925

 

Information regarding invoice #124351. Please review all documentation attached to this e-mail - if you'll have any questions or comments, do not hesitate to contact us.

contact!

Contract data#134512

Screenshot of the attached MS Excel document:

Update 12 December 2024: Zloader is now being distributed in a more targeted way, often by initial access brokers linked to Black Basta ransomware. It is being delivered through Remote Monitoring and Management (RMM) tools like AnyDesk, TeamViewer, and Microsoft Quick Assist.

A new malicious payload, GhostSocks, has been added to the attack chain.

Zloader's configuration is now more secure, using an XOR operation to generate the RC4 key instead of a hardcoded one. It also has improved techniques to avoid detection by malware sandboxes and static signatures.

Zloader now includes an interactive shell for threat actors to execute commands, steal data, and terminate processes. Its communication has also been updated with DNS tunneling, allowing it to tunnel encrypted traffic using custom DNS packets without relying on third-party libraries.

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

Formatting your storage device is one way to remove Zloader malware. However, it is recommended to try running a reputable security tool like Combo Cleaner to remove the malware and avoid data loss that occurs after formating the device.

What are the biggest issues that malware can cause?

Depending on the type of malware, it can cause issues like identity theft, financial losses, reduced computer performance, additional infections, data loss, and more.

What is the purpose of ZLoader?

The purpose of Zloader malware is primarily to serve as a tool for initial access into corporate environments. Originally designed for banking fraud, it now functions to gain entry into networks, enabling the deployment of ransomware.

How did ZLoader infiltrate my computer?

ZLoader was initially spread through malicious websites and emails with harmful attachments. Now, threat actors deploy Zloader through a multi-stage infection process, beginning with Remote Monitoring and Management (RMM) tools such as AnyDesk, TeamViewer, and Microsoft Quick Assist.

Will Combo Cleaner protect me from malware?

Yes, Combo Cleaner can detect and remove nearly all known malware infections. However, high-end malware often hides deep within the system, so performing a full system scan is recommended to successfully detect and eliminate malware.