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WORM_ONLINEG.ZD

October 08, 2012
 Analysis by: Marfel Tiamzon
 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 arrives by connecting affected removable drives to a system. It arrives via removable drives.

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

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

104,415 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Jun 2009

Payload:

Connects to URLs/Ips, Hides files and processes

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It arrives via removable drives.

Installation

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

  • %system%\xvassdf.exe
  • {drive}:\0yml2bch.bat

It drops the following component file(s):

  • %System%\4tddfwq{random number}.dll - also detected as WORM_ONLINEG.ZD
  • {drive}:\autorun.inf

(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 injects threads into the following normal process(es):

  • Explorer.exe

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
54dfsger = %system%\xvassdf.exe

Other System Modifications

This worm adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\MNDOWN
@ =  

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\MADOWN
@ =  

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

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 2

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

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = 0

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

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • 0yml2bch.bat

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[AutoRun]
open=0yml2bch.bat
shell\open\Command=0yml2bch.bat

Dropping Routine

This worm sets the attributes of its dropped file(s) to the following:

  • Hidden
  • Read-Only
  • System

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}a.com/rb/ar1.rar

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

8.900

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

Restart in Safe Mode

[ Learn More ]

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_CLASSES_ROOT\CLSID\
    • MNDOWN
    HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\
    • MADOWN 

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • 54dfsger=%system%\xvassdf.exe

Step 5

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: Hidden=2
      To: Hidden=1
  • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: ShowSuperHidden=0
      To: ShowSuperHidden=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • From: CheckedValue=0
      To: CheckedValue=1

Step 6

Search and delete AUTORUN.INF files created by WORM_ONLINEG.ZD that contain these strings

[ Learn More ]
[AutoRun]
open=0yml2bch.bat
shell\open\Command=0yml2bch.bat

Step 7

Scan your computer with your Trend Micro product to delete files detected as WORM_ONLINEG.ZD. 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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