Analysis by: Erika Bianca Mendoza
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Propagates via instant messaging applications

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

It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

  TECHNICAL DETAILS

File Size: Varies
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 31 Oct 2011

Arrival Details

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

Installation

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

  • %Windows%\dc.exe
  • %Windows%\Help\Other.exe
  • %Windows%\SVIQ.EXE
  • %Windows%\inf\Other.exe
  • %System%\Fun.exe
  • %System%\WinSit.exe
  • %System%\config\Win.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %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 uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • PEINFECT

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
dc2k5 = "%Windows%\SVIQ.EXE"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Fun = "%System%\Fun.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dc = "%Windows%\dc.exe"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
load = "%Windows%\inf\Other.exe"

(Note: The default value data of the said registry entry is {blank}.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe %System%\WinSit.exe"

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

Propagation

This worm sends the following messages using the aforementioned Instant Messaging applications:

Olalala, may tinh cua ban da dinh Worm DungCoi...........
http://{BLOCKED}b.googlepages.com/NWB.txt

It sends messages that contain links to sites hosting remote copies of itself using the following instant-messaging (IM) applications:

  • Yahoo! Messenger

NOTES:

It also attempts to add the following user ID in the affected system's Yahoo! Messenger contacts:

  • dungcoi_vb

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.538.06
FIRST VSAPI PATTERN DATE: 31 Oct 2011
VSAPI OPR PATTERN File: 8.539.00
VSAPI OPR PATTERN Date: 31 Oct 2011

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_IMAUT.SMO

[ 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
    • dc2k5 = "%Windows%\SVIQ.EXE"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Fun = "%System%\Fun.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dc = "%Windows%\dc.exe"

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 NT\CurrentVersion\Windows
    • From: load = "%Windows%\inf\Other.exe"
      To: load = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "Explorer.exe %System%\WinSit.exe"
      To: Shell = Explorer.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as WORM_IMAUT.SMO. 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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