Step-by-Step Guide: Using a Necurs Removal Tool to Clean Your PC

Emergency Necurs Removal Tool: Remove the Botnet Malware FastNecurs is a sophisticated and long-running botnet family that has been used to distribute banking trojans, ransomware, and large-scale spam campaigns. If you suspect Necurs infection, acting quickly helps limit data loss, lateral spread, and further abuse of your machine. This article explains how Necurs behaves, how to confirm infection, and provides a step-by-step emergency removal plan using reputable tools and manual methods.

What is Necurs?

Necurs is a modular botnet and malware family first observed in the early 2010s. It commonly functions as a dropper or loader — once it infects a machine, it can download and install additional payloads such as ransomware (e.g., Locky), banking trojans, or spam-sending components. Necurs is notable for:

• High persistence mechanisms that survive reboots and evade simple removal attempts.
• Modular architecture allowing operators to update components, deliver new payloads, and control infected hosts remotely.
• Large-scale spam and distribution used to propagate other malware via email attachments, malicious links, and social engineering.

Signs of Necurs infection

Look for these indicators:

• Sudden spike in outgoing email or network traffic.
• Unknown processes running (often with random or benign-looking names).
• Unusual scheduled tasks, new services, or altered startup entries.
• Ransomware notes or encrypted files (if a secondary payload executed).
• Browser redirects, missing files, or degraded system performance.

Immediate steps (Emergency response)

1. Isolate the machine

   • Disconnect from networks immediately (unplug Ethernet, disable Wi‑Fi). This prevents lateral movement and stops the botnet from contacting its command-and-control servers.

2. Preserve evidence (if needed)

   • If the device is part of a business or you may need forensics, image the drive before making changes. Use a write-blocker or a trusted imaging tool.

3. Boot into safe environment

   • Restart into Safe Mode (Windows) or use a clean rescue environment (bootable antivirus rescue USB). This reduces the chance the malware can actively block removal.

4. Use an up-to-date antimalware scanner

   • Run a full scan with a reputable antivirus/anti-malware product that specifically detects Necurs and its components. Ensure the tool’s signatures and engine are fully updated before scanning.

Recommended tools for emergency removal

• Windows Defender (built-in, updated) — can detect many Necurs components when signatures are current.
• Malwarebytes (Premium) — strong at detecting loaders and PUPs.
• ESET Online Scanner / ESET NOD32 — good at rootkit and persistence detection.
• Kaspersky Rescue Disk — bootable environment to scan systems without loading Windows.
• Sophos Free Tools or HitmanPro — useful as second-opinion scanners.

Use a combination of a bootable rescue disk and at least two different on-disk scanners for better coverage.

Step-by-step removal procedure

1. Boot into a clean environment

   • Prefer a bootable rescue disk (Kaspersky/ESET/Bitdefender Rescue) or Safe Mode with Networking.

2. Update scanning definitions

   • If using a rescue environment that allows updates, fetch the latest definitions before scanning.

3. Run full system scans with at least two reputable scanners

   • Quarantine detected items. Reboot and run scans again until clean.

4. Check for persistence mechanisms manually

   • Review and remove suspicious entries:
     • Services: sc query / sc delete (or use Autoruns).
     • Scheduled Tasks: Task Scheduler library for unknown tasks.
     • Startup entries: MSConfig or Autoruns for anything suspicious.
     • Browser extensions and proxy settings.

5. Use Autoruns (Sysinternals)

   • Autoruns reveals startup references across many locations; uncheck/delete entries tied to unknown executables. Note paths and hashes for records.

6. Inspect network activity and hosts file

   • Reset hosts file if it contains suspicious redirections. Check open connections with netstat -ano and identify suspicious binaries by PID.

7. Remove residual files and registry keys

   • Only if you’re comfortable; otherwise rely on professional tools. Back up the registry before edits.

8. Reset credentials and MFA

   • Change passwords on accounts used from the infected machine. Assume credentials may have been captured. Enable multi-factor authentication where possible.

9. Rebuild or reimage if unsure

   • If Necurs installed additional payloads or you can’t be certain all persistence is removed, reimage the system from a known-good backup or perform a clean OS reinstall.

Post-removal hardening

• Apply all OS and application updates.
• Harden email defenses: spam filters, attachment policies, and user training.
• Use least-privilege accounts — restrict admin rights.
• Deploy endpoint protection with EDR capabilities for behavioral detection.
• Monitor network traffic and internal logs for re-infection signs.

When to involve professionals

• The machine is part of a business or critical infrastructure.
• Evidence of data exfiltration, extortion, or wide-scale infection.
• You lack secure backups, or multiple systems show signs of compromise.
• Legal/regulatory data breach obligations may apply.

Quick checklist (Emergency)

• Disconnect from network.
• Image the drive (if needed).
• Boot from rescue media.
• Update malware definitions.
• Scan with multiple tools and quarantine/remove.
• Remove persistence (Autoruns, Task Scheduler, Services).
• Change all passwords and enable MFA.
• Reimage if uncertain.

Final notes

Necurs is resilient and often accompanies additional malware, so single-tool scans can miss components. Using multiple detection methods, bootable rescue environments, and—when necessary—professional incident response will give the best chance of fully removing the botnet payload and preventing future reinfection.