Modified by: Christopher Daniel So

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, Spammed via email

This Trojan arrives as attachment to mass-mailed email messages. It may be dropped by other malware.

It does not have any propagation routine.

It does not have any backdoor routine.

It does not have any downloading capability.

  TECHNICAL DETAILS

File Size: Varies
File Type: EXE, DLL
Memory Resident: Yes
Initial Samples Received Date: 22 May 2012

Arrival Details

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

It may be dropped by other malware.

Installation

This Trojan drops the following files:

  • %System Root%\Documents and Settings\All Users\Application Data\win3dx.DLL - also detected by Trend Micro as TROJ_EPHI.FUB
  • %User Temp%\1234.exe - also detected by Trend Micro as TROJ_EPHI.FUB

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

It drops the following non-malicious file:

  • %User Temp%\a.pdf

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

Autostart Technique

This Trojan registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\win3dx
Type = "10"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\win3dx
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\win3dx
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\win3dx
ImagePath = "%SystemRoot%\system32\svchost.exe -k LocalService"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\win3dx
DisplayName = "win3dx"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\win3dx
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\win3dx\Parameters
ServiceDll = "%System Root%\Documents and Settings\All Users\Application Data\win3dx.DLL"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\win3dx\Parameters
ServiceMain = "FnqBcz"

It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\win3dx

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
LocalService = "{List of Local Services} win3dx"

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

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Download Routine

This Trojan does not have any downloading capability.

NOTES:

It takes screenshots of the infected system and sends the images to the following remote server:

  • usa.{BLOCKED}d.com:80

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.130.05
FIRST VSAPI PATTERN DATE: 22 May 2012
VSAPI OPR PATTERN File: 9.131.00
VSAPI OPR PATTERN Date: 23 May 2012

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

Search and delete this file

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.
  • %User Temp%\a.pdf

Step 4

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • win3dx

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • From: LocalService = "{List of Local Services} win3dx"
      To: LocalService = "{List of Local Services}"

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_EPHI.FUB. 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.


Did this description help? Tell us how we did.

Related Malware