Nymeria Trojan

What is Nymeria?

Nymeria (also known as Loda or LodaRAT) is a high-risk trojan virus, which serves as a keylogger and a remote access tool (RAT). This malware is written in the AutoIT scripting language. Although quite simple from a technical point of view, Nymeria is extremely dangerous and can cause issues relating to computer safety and privacy.

Research shows that, in most cases, cyber criminals proliferate Nymeria using spam email campaigns.

As mentioned above, Nymeria is capable of performing various actions depending on the 'threat actor', since Nymeria is designed to receive commands from a Command & Control (C&C server). After successful infiltration, Nymeria places a copy of its executable image in the "%TEMP%" folder and creates a scheduled task so that it runs constantly.

Furthermore, Nymeria records various system parameters/information and sends this to the remote server. You can view the list of collected data below. Communication is then made with the C&C server from which Nymeria is capable of downloading and uploading files.

It also records keystrokes and sends recorded data to the C&C. Nymeria is able to control the computer's webcam, microphone, close running processes, and perform a number of other malicious tasks (Nymeria functionality is also listed below).

The program is controlled via an identical C&C server - in this way, criminals remotely send specific commands for Nymeria to perform. The presence of this malware can lead to serious consequences. Firstly, cyber criminals might gain access to the victim's personal accounts, including email, social network, banks, and so on.

They can steal victims' identities, cause various privacy issues, and steal money. Furthermore, since Nymeria downloads and executes various files, it can be used to as a 'backdoor' to infiltrate other malware into the system. Previously, Nymeria has been used to proliferate another high-risk malware infection called ISR Stealer, which also steals account credentials.

In fact, malware capable of performing a specific set of actions is often used to proliferate other viruses that cover different functionality. Whatever the case, the presence of Nymeria might lead to infiltration of ransomware, which could lead to permanent data loss - ransomware-type viruses are designed to encrypt files and make ransom demands.

Paying any ransom gives no real value, since criminals often ignore victims. Therefore, if you are affected by a ransomware infection, the best solution is to restore everything from a backup. Note that Nymeria can manipulate the computer webcam and microphone, both of which can be used to record the user.

Cyber criminals often make claims that they have recorded compromising material and use this for blackmail purposes. In summary, Nymeria poses a significant threat to your privacy, computer, data, and financial safety. Therefore, eliminate this infection immediately.

There are many trojan-type viruses similar to Nymeria including, for example, FormBook, Hancitor, TrickBot, and Adwind. Not all are as versatile as Nymeria. Some gather information, whilst others misuse system resources to mine cryptocurrency or cause "chain infections".

Although this behavior differs, their presence can lead to issues relating to privacy and computer safety. Therefore, you should eliminate these threats immediately.

How did Nymeria infiltrate my computer?

As mentioned above, Nymeria is usually distributed using spam email campaigns. Cyber criminals send thousands of deceptive emails with malicious attachments (typically Microsoft Word documents). These emails contain deceptive messages encouraging users to open attached files (or, in some cases, links that lead to these files).

Criminals often claim to be employees of popular companies and present these attachments as invoices, bills, etc. Once opened, the MS Office documents ask users to enable macro commands, however, in doing so, users inadvertently grant permission for attachments to be downloaded and Nymeria installed onto the system.

Although most files used to proliferate Nymeria are Microsoft Word documents, it has also been proliferated using direct download links, PDFs, and executable files.

How to avoid installation of malware?

Lack of knowledge and careless behavior are the main reasons for computer infections. The key to safety is caution. Therefore, pay attention when browsing the internet. We recommend that you think carefully before opening email attachments. If the file/link has been sent by someone suspicious/unrecognizable or it seems irrelevant (does not concern you), do not open it.

Bear in mind that these people often abuse users' curiosity - do not fall for this ploy. Have legitimate anti-virus/anti-spyware software installed and running, since these tools can detect and eliminate malware before it does any damage.

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 Nymeria executable in "%TEMP%" folder:

Malicious attachment distributing Nymeria:

List of system information gathered by Nymeria:

• A hard coded string (seen ‘victim’, ‘Clientv4’)
• Hard coded string (seen ‘ddd’)
• Installed AV Vendor (enumerated via running process names)
• Malware version, i.e. 1.0.1
• Monitor resolution in a special format ("Pr[Height]X2[Width]X3")
• OS type (can be "laptop", "Desktop", or "x", enumerated using the WMI query "Select * from Win32_SystemEnclosure")
• User account name
• Version (beta)
• Victim’s Country
• Victim’s IP address
• Webcam installed (Yes or No, enumerated using capGetDriverDescription from Avicap32.dll)
• Windows architecture (X64 or X86)
• Windows version

List of Nymeria's features:

• Basic ShellExecute command
• Capture screenshot and send to C&C
• Change wallpaper via registry modifications
• Close a running process
• Close windows media player (likely related to above)
• Copy file or directory (paths requested from C&C)
• Create a GUI Chat window (Victim/Attacker conversation saved to a file; see Figure 8)
• Delete Chrome/Firefox cookies (closes browsers to do this)
• Delete keylogger data
• Detect UAC settings
• Download and execute a file (HTTP path specified from C&C)
• Download and play .wav files from C&C
• Enumerate attached drives
• Enumerate common folder locations (Desktop/Pictures/Profile/Appdata/Temp)
• Execute a hidden Windows Media Player streaming from an arabic radio MMS
• Get file or directory sizes (path requested from C&C)
• Open/Close CD tray
• Read text to victim using SAPI.SpVoice (text sent from C&C)
• Receive data from C&C and write as binary (executable) and run it
• Receive text from C&C and write to file (likely for batch files)
• Record Webcam
• Record microphone sounds using Windows Sound Recorder
• Send a file to C&C
• Send mouse clicks (left or right being separate commands)
• Send running process names to C&C
• Shutdown victim PC
• Upload keylogger data
• Zip/Unzip files (to exfil to C&C or to decompress from C&C)

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.