BKDR_PLUGX.BS

May 29, 2013
 Analysis by: Nikko Tamana
 ALIASES:

Backdoor:Win32/Plugx.B (Microsoft), a variant of Win32/Korplug.AG trojan (NOD32)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size:

45,056 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

28 May 2013

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This backdoor drops the following file(s)/component(s):

  • %All Users Profile%\NVIDIA MAX\Nv.exe
  • %All Users Profile%\NVIDIA MAX\NvSmart.hlp
  • %All Users Profile%\NVIDIA MAX\NvSmartMax.cpu
  • %All Users Profile%\NVIDIA MAX\NvSmartMax.dll

(Note: %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.)

It creates the following folders:

  • %All Users Profile%\NVIDIA MAX

(Note: %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.)

Autostart Technique

This backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NVIDIA Smart Maximise Helper Host
Type = "110"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NVIDIA Smart Maximise Helper Host
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NVIDIA Smart Maximise Helper Host
ErrorControl = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NVIDIA Smart Maximise Helper Host
ImagePath = "%All Users Profile%%\NVIDIA MAX\Nv.exe" 200 0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NVIDIA Smart Maximise Helper Host
DisplayName = "NVIDIA Smart Maximise Helper Host"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NVIDIA Smart Maximise Helper Host
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NVIDIA Smart Maximise Helper Host
Description = "NVIDIA Smart Maximise Helper Host"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CLASSES_ROOT\FAST

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
User Agent

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
User Agent\Post Platform

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
5.0\User Agent

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
5.0\User Agent\Post Platform

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
FAST

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\NVIDIA Smart Maximise Helper Host

It adds the following registry entries as part of its installation routine:

HKEY_CLASSES_ROOT\FAST
CLSID = "{Hex Values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
FAST
CLSID = "{Hex Values}"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyEnable = "0"

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

HKEY_CURRENT_CONFIG\Software\Microsoft\
windows\CurrentVersion\Internet Settings
ProxyEnable = "0"

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

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.946.01

FIRST VSAPI PATTERN DATE:

28 May 2013

VSAPI OPR PATTERN File:

9.947.00

VSAPI OPR PATTERN Date:

29 May 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

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
    • FAST
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • User Agent
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\User Agent
    • Post Platform
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0
    • User Agent
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent
    • Post Platform
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
    • FAST
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • NVIDIA Smart Maximise Helper Host

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\Internet Settings
    • From: ProxyEnable = "0"
      To: ProxyEnable = "1"
  • In HKEY_CURRENT_CONFIG\Software\Microsoft\windows\CurrentVersion\Internet Settings
    • From: ProxyEnable = "0"
      To: ProxyEnable = "1"

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %All Users Profile%\NVIDIA MAX

Step 6

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