TROJ_THOPER.AD


 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan may be dropped by other malware.

It modifies the Internet Explorer Zone Settings.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

73,152 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

08 May 2012

Arrival Details

This Trojan may be dropped by other malware.

Installation

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

  • %System%\msimegub.bpl

(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 files:

  • %System%\drivers\{BC87739C-6024-412C-B489-B951C2F17000}.SYS

(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 terminates the execution of the copy it initially executed and executes the copy it drops instead.

Autostart Technique

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

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

(Note: The default value data of the said registry entry is 3.)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\stisvc\Parameters
ServiceDll = "%System%\msimegub.bpl"

(Note: The default value data of the said registry entry is %SystemRoot%\system32\wiaservc.dll.)

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{BC87739C-6024-412c-B489-B951C2F17000}

HKEY_CURRENT_USER\Software\Microsoft\
CTF\TIP\{1188450c-fdab-47ae-80d8-c9633f71be64}\
LanguageProfile\0x00000000\{63800dac-e7ca-4df9-9a5c-20765055488d}

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{BC87739C-6024-412c-B489-B951C2F17000}
ImagePath = "\??\%System%\Drivers\{BC87739C-6024-412c-B489-B951C2F17000}.sys"

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

This Trojan deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.982.01

FIRST VSAPI PATTERN DATE:

09 May 2012

VSAPI OPR PATTERN File:

8.983.00

VSAPI OPR PATTERN Date:

09 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

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\SYSTEM\CurrentControlSet\Services\{BC87739C-6024-412c-B489-B951C2F17000}
    • ImagePath = "\??\%System%\Drivers\{BC87739C-6024-412c-B489-B951C2F17000}.sys"

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
    • {BC87739C-6024-412c-B489-B951C2F17000}
  • In HKEY_CURRENT_USER\Software\Microsoft\CTF\TIP\{1188450c-fdab-47ae-80d8-c9633f71be64}\LanguageProfile\0x00000000
    • {63800dac-e7ca-4df9-9a5c-20765055488d}

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\SYSTEM\CurrentControlSet\Services\stisvc
    • From: Start = "2"
      To: Start = "3"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\stisvc\Parameters
    • From: ServiceDll = "%System%\msimegub.bpl"
      To: ServiceDll = "%SystemRoot%\system32\wiaservc.dll"

Step 6

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.
  • %System%\drivers\{BC87739C-6024-412C-B489-B951C2F17000}.SYS

Step 7

Reset Internet security settings

[ Learn More ]

Step 8

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