Quick Links
  • Save & Share
  • Choose your country:

Malware type: Worm

Aliases: Trojan-Downloader.Win32.Cntr.v (Kaspersky), Troj/Dorf-BI (Sophos),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 98, ME, NT, 2000, XP, Server 2003

Encrypted: Yes

Overall risk rating:

Reported infections:

Damage potential:


Distribution potential:



To get a one-glance comprehensive view of the behavior of this malware, refer to the Behavior Diagram shown below.

WORM_NUWAR.APJ Behavior Diagram

Malware Overview

This worm arrives as attachment to email messages spammed by another malware or a malicious user. It may be downloaded from remote sites by other malware. It may be downloaded from certain remote sites.

It drops copies of itself. It also drops files/components.

It creates a registry entry to enable its automatic execution at every system startup.

It opens a random port to allow a remote user to connect to the affected system. Once a successful connection is established, the remote user executes commands on the affected system.

For additional information about this threat, see:

Description created: May. 8, 2008 2:43:24 AM GMT -0800

Minimum scan engine version needed: 8.300

Pattern file needed: 5.281.00

Pattern release date: May 18, 2008

Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.


Note: To fully remove all associated malware, perform the clean solutions for TROJ_DLOAD.HZ.

Identifying the Malware Files

  1. Scan your computer with your Trend Micro antivirus product.
  2. Note the path and file name of all files detected as WORM_NUWAR.APJ.

Trend Micro customers need to download the latest virus pattern file before scanning their computer. Other users can use Housecall, the Trend Micro online threat scanner.

Important Windows ME/XP Cleaning Instructions

Users running Windows ME and XP must disable System Restore to allow full scanning of infected computers.

Users running other Windows versions can proceed with the succeeding solution set(s).

Terminating the Malware Program

This procedure terminates the running malware process. You will need the name(s) of the file(s) detected earlier.

If the process you are looking for is not in the list displayed by Task Manager, proceed to the succeeding solution set.

  1. Open Windows Task Manager.
    • On Windows 98 and ME, press
    • On Windows NT, 2000, XP, and Server 2003, press
    CTRL+SHIFT+ESC, then click the Processes tab.
  2. In the list of running programs*, locate the malware file(s) detected earlier.
  3. Select one of the detected files, then press either the End Task or the End Process button, depending on the version of Windows on your computer.
  4. Do the same for all detected malware files in the list of running processes.
  5. To check if the malware process has been terminated, close Task Manager, and then open it again.
  6. Close Task Manager.

*NOTE: On computers running Windows 98 and ME, Windows Task Manager may not show certain processes. You can use a third party process viewer such as Process Explorer to terminate the malware process.

On computers running all Windows platforms, if the process you are looking for is not in the list displayed by Task Manager or Process Explorer, continue with the next solution procedure, noting additional instructions. If the malware process is in the list displayed by either Task Manager or Process Explorer, but you are unable to terminate it, restart your computer in safe mode.

Deleting the Malware File(s)

  1. Right-click Start then click Search... or Find..., depending on the version of Windows you are running.
  2. In the Named input box, type:
    (Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
  3. In the Look In drop-down list, select the drive that contains Windows, then press Enter.
  4. Once located, select the file then press SHIFT+DELETE.

Removing Autostart Entries from the Registry

This solution deletes/modifies registry keys/entries added/modified by this malware. Before performing the steps below, make sure you know how to back up the registry and how to restore it if a problem occurs. Refer to this Microsoft article for more information about modifying your computer's registry.

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:
  3. In the right panel, locate and delete the entry:
    herjek = "%Windows%\herjek.exe"
  4. Close Registry Editor.

Running Trend Micro Antivirus

If you are currently running in safe mode, please restart your computer normally before performing the following solution.

Scan your computer with Trend Micro antivirus and delete files detected as WORM_NUWAR.APJ and TROJ_DLOAD.HZ. To do this, Trend Micro customers must download the latest virus pattern file and scan their computer. Other Internet users can use HouseCall, the Trend Micro online virus scanner.

Trend Micro offers best-of-breed antivirus and content-security solutions for your corporate network, small and medium business, mobile device or home PC.