How to remove ClosedQuorum RAT from the operating system

What kind of malware is ClosedQuorum?

ClosedQuorum is a Windows implant classified as a trojan that combines Remote Access Trojan (RAT) functionality with credential and cryptocurrency theft. What sets it apart is its use of commercial AI language models to autonomously decide which attack action to take next, without requiring a human operator to send commands.

Once active, the malware queries up to four AI services, tallies their responses, and executes one of four predefined actions: steal credentials, inject malicious code, establish persistence, or attempt lateral movement. Stolen data is sent to the attacker through a Discord webhook rather than a conventional command-and-control server.

According to research published by Cisco Talos, ClosedQuorum is the first documented implant to delegate tactical decisions entirely to AI models. The analyzed samples contain placeholder credentials, and no confirmed in-the-wild deployments have been reported at the time of writing.

ClosedQuorum overview

ClosedQuorum is compiled in Go and runs on 64-bit Windows systems. Instead of contacting a dedicated command-and-control server, it sends requests to up to four commercial AI providers: DeepSeek, Qwen, Mistral, and Google Gemini.

Each model receives a system prompt instructing it to act as a malware strategist and return one of four predefined decisions: steal, inject, persist, or move. The responses are compared using a plurality vote. If the result is tied, DeepSeek has tiebreaker priority.

This architecture shifts attack decision-making off the operator and onto commercial AI infrastructure. The malware can keep executing attack stages autonomously even when no operator is actively watching, which Cisco Talos describes as a form of "effort displacement."

ClosedQuorum's capabilities

The steal action directs ClosedQuorum to dump credentials from LSASS memory using the MiniDumpWriteDump function, extract saved passwords and session data from Chrome, Edge, and Firefox, and collect files from cryptocurrency wallet software and browser extensions including MetaMask, Exodus, and Ethereum.

The inject action executes shellcode inside another running process using either Early Bird APC injection or process hollowing with a PEB-walk technique. Both methods allow the malware to run code under the cover of a legitimate process.

The persist action creates a Windows Registry Run key, registers a scheduled task, and sets up a WMI event subscription that fires every 60 seconds. These three mechanisms work independently, making the infection harder to fully eliminate.

The move action is designed for lateral movement through the local network. In the samples analyzed by Cisco Talos, this option is present in the code but non-functional, suggesting it is reserved for future builds.

Stealth and data exfiltration

To hinder behavioral monitoring, ClosedQuorum overwrites the EtwEventWrite function, suppressing Event Tracing for Windows (ETW) - a logging mechanism many security tools depend on to detect suspicious activity.

The malware delays its first action by five minutes after launch and then polls the AI providers at randomized intervals of five to fifteen minutes. This timing helps avoid sandbox analysis environments, which typically run samples for a fixed short window.

ClosedQuorum disguises itself using Windows Update-themed filenames. Before exfiltration, stolen data is encrypted with AES-256-GCM using a date-derived key, Base64-encoded, and split into 1,900-byte chunks transmitted to the operator via a Discord webhook.

Conclusion

ClosedQuorum is a stealthy, self-directing threat capable of stealing browser credentials, system passwords, and cryptocurrency wallet data, injecting code into other processes, and maintaining persistent access through multiple independent mechanisms.

Its AI-driven decision loop makes it more unpredictable than conventional malware: it does not wait for operator input and can keep executing attack stages on its own. Any machine found to be infected with ClosedQuorum should be cleaned immediately.

More examples of RATs are DarkTortilla, PEEP, and PollCat.

How did ClosedQuorum infiltrate my computer?

As documented by Cisco Talos, ClosedQuorum follows a credentials-as-a-service distribution model aimed at criminal operators. Developers produce a customized binary for each buyer, embedding that operator's LLM API keys and Discord webhook URL at compile time. Every resulting build is unique, with its own exfiltration channel.

The specific methods used to deliver ClosedQuorum to end victims have not been confirmed in the analyzed samples. That said, malware of this category is commonly distributed through phishing emails carrying malicious attachments, fake download pages impersonating legitimate software, and deceptive ads.

Other typical delivery routes include pirated software and activation cracks, third-party download platforms, malvertising, and fake software update prompts. File formats commonly used to package such payloads include ZIP, RAR, EXE, and MSI archives.

How to avoid installation of malware?

Be cautious with unexpected emails, particularly those containing attachments or links from unfamiliar senders. Download software only from official developer websites and verified app stores. Avoid pirated content, key generators, and activation tools sourced from unofficial channels, as these are among the most common delivery vehicles for malware.

Keep your operating system and all installed software up to date, since outdated applications are a frequent target for exploitation. Use reputable security software and run regular system scans to catch threats early. 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.

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

Formatting will remove ClosedQuorum, but it also erases every file on the drive. Running a reputable security tool such as Combo Cleaner is the safer first step in most cases, since it can eliminate the infection without destroying your data.

What are the biggest issues that ClosedQuorum malware can cause?

ClosedQuorum can steal browser passwords, system credentials, and cryptocurrency wallet contents. It can also inject malicious code into running processes and entrench itself through multiple persistence mechanisms.

These capabilities can lead to account hijacking, financial loss through stolen cryptocurrency, identity theft, and the delivery of additional malware to the compromised machine.

What is the purpose of ClosedQuorum malware?

ClosedQuorum is designed to automate post-compromise attack stages using AI decision-making. Its primary goals are stealing credentials and cryptocurrency wallet data, with additional capabilities for code injection, persistence, and lateral movement.

How did ClosedQuorum malware infiltrate my computer?

ClosedQuorum is sold as a customized build to criminal operators, with each binary carrying unique API keys and an exfiltration channel. The actual delivery to victims likely follows common methods such as phishing emails, fake software downloads, pirated content, or malicious advertisements.

Will Combo Cleaner protect me from malware?

Yes. Combo Cleaner can detect and remove most known malware. Because threats like ClosedQuorum use several independent persistence mechanisms, running a full system scan is recommended to make sure the infection is completely cleared.