Analysis by: Karl Dominguez

 PLATFORM:

Windows 2000, XP, Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Propagates via removable drives, Propagates via email

It checks if it has already infected the Microsoft Word global template, Normal.dot by checking for the existence of a registry key.

Infected document files are detected by Trend Micro as WM_GROUCH.A.

It propagates via email by sending a copy of itself to addresses found in the Microsoft Outlook address book.

It then deletes each message as they are sent.

It keeps a list of all email address that it has sent in a certain registry key.

It deletes all files in the %Windows% folder if the current date is May 9 and displays a message box.

This worm arrives as attachment to mass-mailed email messages. It arrives via removable drives.

It gathers target email addresses from cached email, address books, and mailboxes.

  TECHNICAL DETAILS

File Size: 23,004 bytes
File Type: VBS
Memory Resident: Yes
Initial Samples Received Date: 13 Mar 2003
Payload: Modifies files

Arrival Details

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

It arrives via removable drives.

It may arrive via network shares.

Installation

This worm drops the following files:

  • %System%\WinGrc32.dll - detected as WM_GROUCH.A

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It drops the following copies of itself into the affected system:

  • %System%\MSGrc32.vbs
  • %System%\SiteLinks.vbs
  • %System%\Readme.vbs
  • %System%\Mp3Sites.vbs
  • %System%\{random characters}.vbs
  • %Startup%\{random characters}.vbs

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Autostart Technique

This worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
MSGrc32 = Wscript.exe %System%\MSGrc32.vbs %1

Other System Modifications

This worm adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Zed/[rRlf]\
Grouch\1.0
RndCopy = {file name of copy in %Startup% folder}

HKEY_CURRENT_USER\Software\Zed/[rRlf]\
Grouch\1.0\NormalTemplate
(Default) = {day of infection}

HKEY_CURRENT_USER\Software\Microsoft\
Office\{Application Version}\Word\
Security
Level = 1

HKEY_CURRENT_USER\Software\Zed/[rRlf]\
Grouch\1.0
(Default) = VBS/Grouch by Zed/[rRlf]

HKEY_CURRENT_USER\Software\Microsoft\
Office\{Application Version}\Word\
Security
AccessVBOM = 1

It adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\Zed/[rRlf]

HKEY_CURRENT_USER\Software\Zed/[rRlf]\
Grouch

HKEY_CURRENT_USER\Software\Zed/[rRlf]\
Grouch\1.0

HKEY_CURRENT_USER\Software\Zed/[rRlf]\
Grouch\1.0\NormalTemplate

HKEY_CURRENT_USER\Software\Zed/[rRlf]\
Grouch\1.0\Outlook

HKEY_CURRENT_USER\Software\Zed/[rRlf]\
Grouch\1.0\Outlook\
RecordContacts

Propagation

This worm drops copies of itself into the following folders used in peer-to-peer (P2P) networks:

  • %Program files%\Kazaa\My Shared Folder
  • C:\Kazaa\My Shared Folder
  • C:\My Downloads
  • %Program files%\KaZaA Lite\My Shared Folder
  • %Program files%\Bearshare\Shared
  • %Program files%\Edonkey2000
  • %Program files%\Morpheus\My Shared Folder
  • %Program files%\Grokster\My Grokster
  • %Program files%\ICQ\Shared Files

It drops the following copy of itself in all physical and removable drives:

  • [drive]:\Saved Document (day of execution}.vbs

It gathers target email addresses from cached email, address books, and mailboxes.

Other Details

This worm does the following:

  • Microsoft Office Word Infection
    Checks if it has already infected the Microsoft Word global template,Normal.dot by checking for the existence of the following registry key:
    HKEY_CURRENT_USER\Software\Zed/[rRlf]\Grouch\1.0\NormalTemplate
    (Default) = {day of infection}
    Infected document files are detected by Trend Micro as WM_GROUCH.A.
  • Uses the following file names for its copies in the said P2P folders:
    • 1000 Porn Sites.vbs
    • Hacking made easy.vbs
    • How to make a virus.vbs
    • Hot Links.vbs
    • How to make a bomb.vbs
  • Email Propagation
    Propagates via email by sending a copy of itself to addresses found in the Microsoft Outlook address book. It sends email with the following details:

    Subject: Check this out
    Message body: Check out these web links, I know you like these sites! ;)
    Attachment: SiteLinks.vbs

    Subject: The File
    Message body: Hello, Here is that file that everyone was asking me for. Don't let anyone else see it, please, because it contains some pretty naughty stuff ;)
    Attachment: SiteLinks.vbs

    Subject: Readme File
    Message body: Hello, I am running a bit late. Just read the Readme file for more information.
    Attachment: Readme.vbs

    Note that on the system date, May 9, it sends email with the following specific format:

    Subject: Fwd: Free Music!
    Message body: Hello! Go to these sites that I'm sending to you now. You can get basically any music file or Music video file that you want! Enjoy!
    Attachment: Mp3Sites.vbs

    It then deletes each message as they are sent.
  • Keeps a list of all email address that it has sent to in the following registry key:
    HKEY_CURRENT_USER\Software\Zed/[rRlf]\Grouch\
    1.0\Outlook\RecordContacts\
  • Deletes all files in the %Windows% folder if the current date is May 9 and displays the following message box:

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 1.483.24
FIRST VSAPI PATTERN DATE: 13 Mar 2003

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware files dropped/downloaded by VBS_GROUCH.A

    •  WM_GROUCH.A

Step 3

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\
    • Zed/rRlf]

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • MSGrc32 = Wscript.exe %System%\MSGrc32.vbs %1
  • In HKEY_CURRENT_USER\Software\Microsoft\Office\{Application Version}\Word\Security
    • Level = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Office\{Application Version}\Word\Security
    • AccessVBOM = 1

Step 5

Scan your computer with your Trend Micro product to delete files detected as
 VBS_GROUCH.A


*Note: If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 6

Restore files from backup Only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on your computer again.


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