How to eliminate the LummaC2 stealer-type malware from your operating system

What is LummaC2?

LummaC2 is the name of a malicious program classified as a stealer. It operates by stealing sensitive information from infected devices and installed applications.

At the time of writing, this malware is sold on the Web; as such, it can be distributed by multiple cyber criminals. According to its promotional material, LummaC2 is lightweight (150-200 KB) and can infect operating systems Windows 7 through Windows 11.

LummaC2 malware overview

The LummaC2 stealer begins its operations by obtaining relevant device data, such as OS version and architecture, hardware ID, CPU, RAM, screen resolution, system language, and so on. This malware can exfiltrate files and extract data from certain applications.

LummaC2 targets the following browsers: Chrome, Chromium, Mozilla Firefox, Microsoft Edge, Brave, Kometa, Opera GX Stable, Opera Neon, Opera Stable, Vivaldi, and others.

From browsers, this stealer may acquire browsing histories, Internet cookies, usernames/passwords, personally identifiable details, credit card numbers, and other highly sensitive information. LummaC2 also targets multiple cryptocurrency (e.g., Binance, Electrum, Ethereum, etc.) and 2FA (Two-Factor Authentication) extensions.

Hence, criminals using this malware can steal a wide variety of vulnerable data and abuse it to generate revenue, e.g., use hijacked accounts to steal the victims' identities, promote scams, proliferate malware, carry out fraudulent transactions, make unauthorized online purchases, and so forth.

In summary, the presence of software like LummaC2 on devices can result in severe privacy issues, significant financial losses, and identity theft.

If you believe that your device is infected with the LummaC2 stealer (or other malware) – immediately use an anti-virus to run a full system scan and remove all detected threats.

Stealer-type malware examples

We have analyzed and researched thousands of malware samples; MintStealer, Rhadamanthys, Demon, and FateGrab are stealers that we have written about most recently.

Malicious software can have a broad range of capabilities – from stealing information to abusing system resources in cryptocurrency mining processes. However, regardless of how malware operates – its presence on a system endangers device integrity and user safety. Therefore, all threats must be removed immediately upon detection.

How did LummaC2 infiltrate my computer?

As previously mentioned, LummaC2 has been observed being sold online. Hence, how this malicious program is distributed depends on the cyber criminals using it at the time.

Generally, malware is proliferated by employing phishing and social engineering tactics. This software is usually presented as or bundled with ordinary content. Malicious files can be PDF and Microsoft Office documents, archives, executables, JavaScript, etc. When such a file is opened – the infection chain is initiated.

Malware is most commonly proliferated via drive-by (stealthy/deceptive) downloads, malicious attachments and links in spam emails/messages, online scams, malvertising, dubious download channels (e.g., unofficial and freeware sites, Peer-to-Peer sharing networks, etc.), illegal software activation ("cracking") tools, and fake updates.

How to avoid installation of malware?

We highly recommend downloading from official and verified sources. Furthermore, all programs must be activated and updated using genuine functions/tools, as illegal activation tools ("cracks") and third-party updaters can contain malware.

Another recommendation is to exercise caution with incoming mail. The attachments and links found in dubious/irrelevant emails and other messages – must not be opened, as they can be malicious and cause infections. We also advise being careful while browsing since fake and hazardous online content usually appears ordinary and innocuous.

We must stress the importance of having a dependable anti-virus installed and kept updated. Security software must be used to run regular system scans and to remove 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.

Screenshot of LummaC2 stealer official sale website:

Appearance of LummaC2 stealer being promoted on hacker forums (GIF):

Screenshot of a crack download website spreading LummaC2 stealer (source: ahnlab.com):

Update 21 November 2023 - The malware has been updated to version 4.0, introducing several noteworthy changes. These include the default implementation of Control Flow Flattening obfuscation, a novel Anti-Sandbox technique that postpones sample detonation until human mouse activity is identified, a shift to XOR encryption for strings rather than straightforward modification, and the incorporation of dynamic configuration files fetched from the Command and Control (C2).

Furthermore, the latest version of the LummaC2 stealer mandates threat actors to utilize a crypter for their builds.

Update August 31, 2026 - Anthropic has confirmed that LummaC2 is among the infostealer malware families being used to steal Claude AI platform login sessions. By extracting browser session cookies, attackers gain access to victims' Claude accounts without needing a password or two-factor authentication, then drain the victim's usage allowance or API credits. Anthropic is revoking affected sessions and issuing refunds for unauthorized usage. (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 LummaC2 malware, should I format my storage device to get rid of it?

No, LummaC2's removal does not require such drastic measures.

What are the biggest issues that LummaC2 malware can cause?

The dangers associated with an infection depend on the program's functionalities and the cyber criminals' modus operandi. LummaC2 is a stealer – a type of malware designed to extract information from infected devices. These types of infections can result in serious privacy issues, financial losses, and identity theft.

What is the purpose of LummaC2 malware?

The primary use of malware is to generate revenue. However, cyber criminals may also employ this software to amuse themselves, carry out personal vendettas, disrupt processes (e.g., websites, services, companies, etc.), and even launch politically/geopolitically motivated attacks.

How did LummaC2 malware infiltrate my computer?

Malware is mainly spread through drive-by downloads, untrustworthy download channels (e.g., freeware and free file-hosting websites, P2P sharing networks, etc.), spam emails and messages, online scams, malvertising, illegal software activation tools ("cracks"), and fake updates. Furthermore, some malicious programs are capable of self-proliferating via local networks and removable storage devices (e.g., external hard drives, USB flash drives, etc.).

Will Combo Cleaner protect me from malware?

Yes, Combo Cleaner is designed to detect and remove threats. It is capable of eliminating practically all known malware infections. However, it must be emphasized that running a full system scan is crucial – since high-end malicious programs typically hide deep within systems.