WORM_NUWAR.AAI

Malware type: Worm

Aliases: W32.Mixor.Q@mm (Symantec), TR/Small.DBY.AF (Avira), Mal/Behav-164 (Sophos),

In the wild: Yes

Destructive: No

Language: English

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

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

High

Infection Channel 1 : Propagates via email


Description: 

Barely three weeks into the new year, as the storm "Kyrill" ravaged over central Europe, another "storm" brewed. The new storm was a deluge of spam email messages that promised to bring information about Europe's most severe winter storm since 1999, with subject lines such as "230 dead as storm batters Europe", among others.

That is how this Trojan, arriving as attachment to the said email messages, came to be dubbed the "Storm" malware. But this Trojan is more than just a malware with a clever social engineering technique. Tagging WORM_NUWAR.CQ along, it created a partnership that staged a complex attack.

To read a comprehensive article about the routines and ultimate goals of the TROJ_SMALL.EDW-WORM_NUWAR.CQ tandem, click here: TROJ_SMALL.EDW Storms into Inboxes, Teams Up with NUWAR to Create Unique Network.

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

WORM_NUWAR.AAI Behavior Diagram

Malware Overview

This worm arrives as an attachment to mass-mailed email messages.

It spreads by attaching a copy of itself to an email message, which it sends using its own Simple Mail Transfer Protocol (SMTP) engine. Having its own SMTP engine allows it to send messages without using any mailing application, such as MS Outlook.

Below is a sample of the email message this worm sends out:

{Sample email message}

It spoofs the From field of an email message by using a list of common names followed by a spoofed domain name. Users may be tricked into thinking that the email message is from a trusted source.

It drops a randomly named file in the folder where this worm is executed. It also drops the file WINCOM32.SYS in the Windows system folder. Both files are detected by Trend Micro as TROJ_SMALL.EDW. As a result, malicious routines of the dropped Trojan are exhibited on the affected system.

It terminates processes, most of which are related to antivirus and security applications. The said routine allows this worm to avoid easy detection and consequent removal.

In addition, it disables Internet Connection Sharing (ICS) and Windows Firewall by modifying a related registry entry.

For additional information about this threat, see:

Description created: Feb. 13, 2007 3:40:30 PM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: 50,547 Bytes (compressed)

Initial samples received on: Feb 13, 2007

Compression type: PEPack

Related toTROJ_SMALL.EDW

Payload 1: Disables Internet Connection Sharing and Windows Firewall

Payload 2: Terminates processes

Payload 3: Drops files

Details:

Arrival, Installation, and Other Registry Modification

This worm arrives as an attachment to mass-mailed email messages.

It drops a randomly named file in the folder where this worm is executed. It also drops the file WINCOM32.SYS in the Windows system folder. Both files are detected by Trend Micro as TROJ_SMALL.EDW. As a result, malicious routines of the dropped Trojan are exhibited on the affected system.

This worm disables Internet Connection Sharing (ICS) and Windows Firewall. It does the said routine by modifying the following registry entry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess
Start = "4"

(Note: The data value of the said registry entry is usually user-defined. When the value is set to 3, the user is required to manually start ICS and Windows Firewall. In effect, the said services are disabled unless started by the user.)

Propagation via Email

This worm spreads by attaching a copy of itself to an email message, which it sends using its own Simple Mail Transfer Protocol (SMTP) engine. Having its own SMTP engine allows it to send messages without using any mailing application, such as MS Outlook.

The email message it sends out has the following details:

Subject: (any of the following)
• A Valentine Love Song
• Be My Valentine
• Fly Away Valentine
• For My Valentine
• Happy Valentine's Day
• My Lucky Valentine
• My Valentine
• My Valentine Heart
• My Valentine Sunshine
• Send Love On Valentines
• The Valentine Love Bug
• The Valentines Angel
• Valentine Letter
• Valentine Love Song
• Valentine Sweetie
• Valentine's Love
• Valentine's Night
• Valentines Day Dance
• Valentines Day is here again
• Your Love on Valentine's

Message body: {blank}

Attachment: (any of the following)

• Flash postcard.exe
• Greeting card.exe
• Greeting Postcard.exe
• Postcard.exe

Below is a sample of the email message this worm sends out:

{Sample email message}

It spoofs the From field of an email message by using the following list of common names followed by a spoofed domain name:

  • Aldora
  • Alysia
  • Amorita
  • Anita
  • April
  • Aretina
  • Barbra
  • Becky
  • Bella
  • Bettina
  • Blenda
  • Briana
  • Bridget
  • Caitlin
  • Camille
  • Carla
  • Carmen
  • Chelsea
  • Clarissa
  • Damita
  • Danielle
  • Daria
  • Diana
  • Donna
  • Doris
  • Ebony
  • Eliza
  • Emily
  • Erika
  • Evelyn
  • Faith
  • Gilda
  • Gloria
  • Haley
  • Helga
  • Holly
  • Idona
  • Isabel
  • Ivana
  • Ivory
  • Janet
  • Jewel
  • Joanna
  • Julie
  • Juliet
  • Kacey
  • Kassia
  • Katrina
  • Laura
  • Linda
  • Lolita
  • Melody
  • Nadia
  • Naomi
  • Natalie
  • Nicole
  • Olivia
  • Pamela
  • Peggy
  • Queen
  • Rachel
  • Sharon
  • Silver
  • Valda
  • Valora
  • Vanessa
  • Vicky
  • Violet
  • Vivian
  • Wendy
  • Willa
  • Xandra
  • Xenia
  • Xylia
  • Zenia
  • Zilya

Process Termination

This worm terminates the following processes, which are related to antivirus and security applications:

  • anti-virus.EXE
  • KAVPF.EXE
  • nav.exe
  • NAVAPSVC.EXE
  • regedit.exe
  • taskmgr.exe

The said routine allows this worm to avoid easy detection and consequent removal.

Other Details

This worm creates the mutex klllekkdkkd to ensure that only one instance of itself exists in the affected system's memory.

It runs on Windows 98, ME, NT, 2000, XP, and Server 2003.

Analysis By: Gus Vincent T. Dato

Revision History:

First pattern file version: 4.267.00
First pattern file release date: Feb 13, 2007

SOLUTION


Minimum scan engine version needed: 8.000

Pattern file needed: 4.301.00

Pattern release date: Feb 27, 2007


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.

Solution:

Note: To fully remove all associated malware, perform the clean solution for TROJ_SMALL.EDW.

Identifying the Malware Program

To remove this malware, first identify the malware program.

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

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

Terminating the Malware Program

Since this malware terminates the Windows Task Manager, it is necessary to use third party process viewers such as Process Explorer. You will need the name(s) of the file(s) detected earlier.

  1. Download Process Explorer.
  2. Extract the contents of the compressed (ZIP) file to a location of your choice.
  3. Execute Process Explorer by double-clicking procexp.exe.
  4. In the Process Explorer window, locate the malware file(s) detected earlier.
  5. Right-click one of the detected files, then click Kill Process Tree.
  6. Do the same for all detected malware files in the list of running processes.
  7. Close Process Explorer.

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

Editing the Registry

This malware modifies the computer's registry. Users affected by this malware may need to modify or delete specific registry keys or entries. For detailed information regarding registry editing, please refer to the following articles from Microsoft:

  1. HOW TO: Backup, Edit, and Restore the Registry in Windows 98 and Windows ME
  2. HOW TO: Backup, Edit, and Restore the Registry in Windows NT 4.0
  3. HOW TO: Backup, Edit, and Restore the Registry in Windows 2000
  4. HOW TO: Back Up, Edit, and Restore the Registry in Windows XP and Server 2003

Restoring Modified Entry from the Registry

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SYSTEM>CurrentControlSet>Services>SharedAccess
  3. In the right panel, locate the entry:
    Start = "4"
  4. The aforementioned entry is user-defined. It has the following parameters:
    • 2 (sets the service to automatic)
    • 3 (sets the service to manual
    • 4 (disables the service)
  5. Right-click on the value name and choose Modify. Change the value data to the preferred parameter.
  6. Close Registry Editor.

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).

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.AAI. 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.




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