How to remove Bizarro trojan from the operating system?

What is the Bizarro trojan?

Bizarro is the name of a banking trojan. This type of malware is designed to target banking information.

Furthermore, these trojans often have additional abilities that expand their area of interest outside of online banks. This applies to Bizarro as well.

The trojan in question is a sophisticated piece of malicious software with many functionalities. It uses strong obfuscation techniques that hinder its detection and analysis.

Bizarro is particularly active in South America and Europe; its target lists include over seventy banks from these continents. Bizarro employs social engineering in its distribution and post-infection operations.

The Bizarro trojan firstly ends running browser processes to terminate active sessions with banking websites. It does this so that victims would be forced to provide their credentials again when accessing their bank accounts, thereby allowing the malicious program to obtain them.

Additionally, Bizarro disables the autofill feature. Hence, victims need to enter their log-in credentials fully when signing in.

This is done to ensure that the malware would be able to acquire the complete banking data. The trojan also uses various pop-up windows and fake error messages to steal two-factor authentication (2FA) codes.

These windows can appear as simple system error messages or ones supposedly displayed by the victims' online banks (containing the appropriate logos and other graphical details). The text presented in these fake messages varies depending on what the malware seeks at that moment.

For example, the pop-ups can request users to enter the data again as it was incorrect, contain allegedly bank-issued instructions, ask confirmation for ongoing operations/transactions, notify of pending system restarts due to security-related processes, and so on. It is noteworthy that Bizarro also attempts to convince users into installing malicious application onto their smartphones.

Once Bizarro has gained the targeted information, it can freeze the system and prevent victims from using the Windows Task Manager - to finish its malicious operations (e.g., complete fraudulent transactions). During this time, victims are presented with fake messages that explain the device's inoperability.

The pop-ups can state that the system, its security software, or browsers have been compromised and require updates. The messages contain progress bars that track the bogus update/installation processes.

However, displaying various windows is not the sole tactic used by Bizarro, nor is it the malware's only functionality. This trojan also has keylogging (key-stroke recording) abilities.

It can control the device's keyboard and mouse; to elaborate, this can be used to interact with confirmation options without user input. Bizarro scours the system for relevant data and content.

It can search folders and files, and subsequently download/upload the latter. Another feature of Bizarro is taking screenshots.

The malicious program monitors clipboard data (copy-paste buffer) for Bitcoin cryptocurrency wallet addresses. If detected, the malware can then replace the copied address with one belonging to the cyber criminals.

Hence, outgoing cryptocurrency transactions can be transferred to the criminals instead of the intended recipients. Furthermore, this trojan can limit the operating system's functionality and restart, shutdown, or damage the system itself.

To summarize, Bizarro infections can result in system damage, severe privacy issues, significant financial losses, and identity theft. If it is known/suspected that Bizarro (or other malware) has already infected the device - an anti-virus must be used to eliminate it without delay.

Ares, Qakbot, Javali, SolarSys, Mekotio, and Zeus Sphinx are some examples of banking trojans. In general, malware can have a variety of purposes and a likewise broad range of functionalities.

Common abilities include: content exfiltration (download) from the infected machine, additional malware installation, data extraction from browsers and other installed applications, file encryption and/or screen locking for ransom purposes (ransomware), enablement of remote access/control over the compromised device (RATs - Remote Access Trojans), key-stroke and/or audio/video recording via microphones and webcams, use of system resources to mine cryptocurrency (cryptominers), and so forth.

Regardless of how malware operates, its infections pose a serious threat to device integrity and user privacy. Therefore, it is strongly advised to remove all infections immediately upon detection.

How did Bizarro infiltrate my computer?

Bizarro has been observed being actively spread through spam campaigns - large-scale operations during which thousands of deceptive/scam emails are sent. Spam emails can have download links of malicious files, and/or the files are simply attached to the letters.

Typically, the Bizarro-spreading emails contain links that download MSI packages (Microsoft/Windows installer package file format). The MSI package downloads a virulent ZIP format archive.

At the time of research, these infectious files were hosted on compromised Amazon (AWS), Azure, and WordPress websites. Once the malicious file is opened - Bizarro program's infection process is triggered.

Malware is not proliferated exclusively via spam campaigns. Another popular technique is distribution through untrustworthy download channels (e.g., unofficial and free file-hosting websites, Peer-to-Peer sharing networks, and other third-party downloaders). Malicious programs are often disguised as or bundled with ordinary software/media.

Therefore, users usually download/install them unintentionally. Illegal activation tools ("cracks") and fraudulent updates are prime examples of content used to spread malicious software. "Cracking" tools can cause infections instead of activating licensed products.

Fake updaters infect systems by exploiting flaws of outdated programs and/or by installing malware instead of the promised updates.

How to avoid installation of malware?

It is highly recommended to exercise caution with incoming emails - to avoid infecting the system via spam mail. Suspicious and irrelevant email letters must not be opened, especially any links or attachments found in them.

Additionally, it is advised to download only from official and verified sources. It is just as important to activate and update programs with tools/functions provided by legitimate developers.

To protect device and user safety, it is crucial to have a reputable anti-virus/anti-spyware suite installed and updated. This software has to be used to run regular system scans and remove detected threats and issues.

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.

Example of a spam email spreading Bizarro trojan:

Text presented within:

Subject: Notificacion de Impuestos Internos

 

Estimado(a) Contribuyente

******* : Le informa que existen obligaciones,
producto de una liquidación tributaria que se encuentra impaga. Una liquidación
tributaria corresponde a la determinación de diferencias de impuesto detectadas
por el SII.  Puede descargar el informe generado por el SII en el siguiente enlance:

Descargar Informe

© 2021 | Santiago | Chile

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.