Removal instructions for the Kazuar malware

What kind of malware is Kazuar?

Kazuar is a backdoor-type malware that has been in use since at least 2017. Throughout the years, several variants of this malicious program have been detected. The latest iteration was discovered in an attack on the Ukrainian defense sector in July 2023.

Kazuar is used by Pensive Ursa (also known as Turla, Uroburos), a threat actor connected to the Federal Security Service of the Russian Federation (FSB). Naturally, attacks involving this malware have geopolitical motivations; known targets include various entities linked to European governments and militaries.

Kazuar malware overview

Kazuar is utilized in the second stage of infections. It can be preceded by the Capibar backdoor in the first stage and subsequently paired with a variety of tools.

Like most programs developed and used by sophisticated cyber criminals, Kazuar is geared towards stealth. This backdoor employs anti-analysis techniques, such as searching for specific debuggers and analysis tools (e.g., dnSpy, Process Monitor, Wireshark, x32dbg, etc.), honeypots, and sandbox environments. The program's use of obfuscation and encryption likewise aid in avoiding detection.

Kazuar's purpose is to serve as an extensive and versatile system profiling tool. This malware has a vast array of data-stealing capabilities. It can also execute scripts (JavaScript, PowerShell, and VBScript), as well as various commands over Command Prompt.

Additionally, the malware can perform automated tasks. For its C&C (Command and Control), Kazuar uses compromised legitimate websites, and this diminishes the chances of site takedown and detection due to suspicious traffic.

Kazuar collects a wide variety of information relating to the infected system, including (but not limited to): hardware details, operating system data, device drivers, network information, user data, UAC settings, existing folders and files (specified formats, e.g., TXT, DOC, DOCX, XLS, XLSX, PPT, PPTX, VBS, CONFIG, JS, etc.), installed applications and anti-virus tools, Internet settings, DNS cache, RDP connections, plugged USB devices, etc.

The malware also monitors victims' activity by gathering the following data: Run command history, searches and paths typed into File Explorer, running processes, active windows, Microsoft Outlook downloads, recently opened Microsoft Office documents, items in the recycle bin, etc.

Other capabilities of this backdoor include process termination, taking screenshots, managing files (e.g., move, copy, exfiltrate/download, delete, etc.), and keylogging (i.e., recording keystrokes).

Kazuar can inject itself into the victim's default browser. It likewise harvests credentials from browsers (including ones based on Chromium and Mozilla) and other applications (full list below). Amongst its target list are email clients, messaging platforms, File Transfer Protocol (FTP) clients, source code control systems, and Virtual Private Network (VPN) clients.

It is pertinent to mention that malware developers commonly improve upon their creations and methodologies. There have already been several versions of Kazuar, this backdoor allows for a certain amount of customizability, and there is evidence suggesting that this program is in active development. Therefore, future Kazuar iterations with different/additional capabilities are likely.

To summarize, the presence of high-risk malware on devices can lead to diminished system performance or failure, data loss, severe privacy issues, financial losses, and identity theft.

It must be mentioned that attacks leveraged against extremely sensitive targets (such as those involving Kazuar) can carry threats of greater significance.

Backdoor-type malware examples

SysUpdate, Sponsor, Merdoor, and MQsTTang are just some of our latest articles on backdoor-type malware. Programs within this classification typically have a strong emphasis on stealth. Backdoors are commonly used to prep systems for further infection (i.e., infiltration of additional malicious programs or components). However, this malware is often utilized for reconnaissance purposes and data theft as well.

It must be mentioned that regardless of how malware operates – the presence of this software on a system threatens device integrity and user safety. Hence, it is paramount to eliminate all threats immediately upon detection.

How did Kazuar infiltrate my computer?

Malware used by sophisticated threat actors is typically proliferated using targeted social engineering tactics and tailor-made phishing campaigns. Kazuar is unlikely to be an exception, as it is used by a threat actor backed by the Russian Federal Security Service (FSB), and attacks involving this backdoor-type program are not random.

To expand upon malware distribution in general, malicious software is usually disguised as or bundled with ordinary program/media files. They come in various formats, e.g., executables (.exe, .run, etc.), archives (ZIP, RAR, etc.), documents (PDF, Microsoft Office, Microsoft OneNote, etc.), JavaScript, and so forth.

Widely used proliferation methods include: malicious attachments or links in spam mail (e.g., emails, PMs/DMs, SMSes, etc.), drive-by (stealthy/deceptive) downloads, malvertising, online scams, dubious download channels (e.g., freeware and free file-hosting websites, Peer-to-Peer sharing networks, etc.), pirated content, illegal software activation tools ("cracks"), and fake updates.

Furthermore, some malicious programs can self-spread 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 treating incoming emails and other messages with caution. Attachments or links present in suspicious/irrelevant mail must not be opened, as they can be infectious. We advise being vigilant while browsing since fake and malicious online content usually appears genuine and harmless.

Another recommendation is to download only from official and verified sources. Additionally, all programs must be activated and updated using legitimate functions/tools, as illegal activation ("cracking") tools and third-party updates may contain malware.

It is paramount to have a dependable anti-virus installed and kept up-to-date. Security software must be used to run regular system scans and to 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.

Browsers targeted by Kazuar malware:

• Google Chrome
• Mozilla Firefox
• Microsoft Edge
• Internet Explorer
• 7Star
• Amigo
• Atom
• Brave
• Cent
• Chedot
• Chrome SxS
• Chromium
• CocCoc
• Comodo
• Comodo IceDragon
• CyberFox
• Elements
• Epic
• K-Meleon
• Kometa
• Mozilla IceCat
• Operar
• Opera GX
• Orbitum
• Sputnik
• Torch
• Uran
• Vivaldi
• Yandex

Miscellaneous applications targeted by Kazuar malware:

• Microsoft Outlook
• Signal
• FileZilla
• WinSCP
• Git SCM
• OpenVPN

Update July 31, 2026 - Kazuar has undergone a significant architectural overhaul, according to new research. The malware - operated by the Russian FSB-linked group also tracked under the name Secret Blizzard - has been rebuilt as a modular peer-to-peer botnet consisting of three distinct components working in concert on infected networks.

In this updated design, infected machines form a self-organizing network and automatically elect one machine as a "leader" to relay commands from attackers, while all other infected systems stay silent to reduce detection risk. The new version also adds capabilities to bypass common security defenses and supports over 150 operator-controlled configuration options. (source: bleepingcomputer.com).

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

Malware removal rarely necessitates formatting.

What are the biggest issues that Kazuar malware can cause?

The dangers associated with an infection depend on the malware's functionalities and the cyber criminals' modus operandi. Kazuar is a second-stage backdoor with extensive system profiling and data stealing capabilities. Typically, infections of this kind can lead to severe privacy issues, financial losses, and identity theft.

It is noteworthy that Kazuar is used by a threat actor linked to the Federal Security Service of the Russian Federation (FSB). Hence, attacks involving this malware carry geopolitical motivations and pose greater threats.

What is the purpose of Kazuar malware?

As indicated in the previous answer, Kazuar is used by Pensive Ursa – a group backed by the FSB. This malware has been used in multiple geopolitically motivated attacks targeting European entities in the governmental and military spheres, including the Ukrainian defense sector.

How did Kazuar malware infiltrate my computer?

In general, malware is mainly spread via spam emails/messages, drive-by downloads, online scams, malvertising, untrustworthy download sources (e.g., freeware and third-party sites, Peer-to-Peer sharing networks, etc.), pirated programs/media, illegal software activation tools ("cracks"), and fake updates. Some malicious programs can even self-proliferate through 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. Note that performing a complete system scan is essential to detection since high-end malicious software typically hides deep within systems.