Analysis by: JasperM
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

It modifies registry entries to hide files with System and Read-only attributes.

  TECHNICAL DETAILS

File Size: 278,528 bytes
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 04 Nov 2010

Arrival Details

This worm may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This worm drops the following copies of itself into the affected system:

  • %User Profile%\yhzem.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
yhzem = %User Profile%\yhzem.exe /W

Other System Modifications

This worm modifies the following registry entries to hide files with System and Read-only attributes:

HKEY_CURRENT_USER\SOFTWARE\MICROSOFT\
Windows\CURRENTVERSION\Explorer\
Advanced
ShowSuperHidden = 0

(Note: The default value data of the said registry entry is 1.)

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 7.594.09
VSAPI PATTERN Date: 04 Nov 2010
VSAPI PATTERN Date: 11/4/2010 12:00:00 AM

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

Identify and terminate files detected as WORM_VB.JDJ

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

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_CURRENT_USER\SOFTWARE\MICROSOFT\Windows\CURRENTVERSION\Run
    • yhzem=%Use Profile%\yhzem.exe /W

Step 4

Restore this modified 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_CURRENT_USER\SOFTWARE\MICROSOFT\Windows\CURRENTVERSION\Explorer\Advanced  
    • From: ShowSuperHidden = 0
      To: ShowSuperHidden = 1

Step 5

Scan your computer with your Trend Micro product to delete files detected as WORM_VB.JDJ. 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.


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