BKDR_PLUGX.CA

 Modified by: Jimelle Monteser

 ALIASES:

Backdoor:Win32/Plugx.A (Microsoft), Backdoor.Korplug (Norton), Backdoor.Win32.Gulpix (Ikarus)

 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:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet


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.

It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

240,674 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

20 Feb 2014

Payload:

Connects to URLs/IPs, Steals information

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 creates the following folders:

  • %All Users Profile%\SxS
  • %User Temp%\RarSFX0

(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.. %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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

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

  • DoInstPrepare

It stays memory-resident by injecting codes into the following processes:

  • svchost.exe

Autostart Technique

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\UPS\Security

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\UPS\Enum

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CLASSES_ROOT\FAST

HKEY_LOCAL_MACHINE\FAST

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_UPS

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_UPS\
0000

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_UPS\
0000\Control

It adds the following registry entries:

HKEY_CLASSES_ROOT\FAST
CLSID = "{random hex values}"

HKEY_LOCAL_MACHINE\FAST
CLSID = "{random hex values}"

It modifies the following registry key(s)/entry(ies) as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\UPS
ImagePath = ""%System%\Nv.exe" 2000"

(Note: The default value data of the said registry entry is "%System%\ups.exe".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\UPS
Type = "110"

(Note: The default value data of the said registry entry is "10".)

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

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\UPS
ErrorControl = "0"

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\UPS
DisplayName = "ups"

(Note: The default value data of the said registry entry is "Uninterruptible Power Suply".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\UPS
ObjecName = "LocalSystem"

(Note: The default value data of the said registry entry is "NT AUTHORITY\LocalSevice".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\UPS
Description = "ups"

(Note: The default value data of the said registry entry is "Manages an uninterruptible power supply (UPS) connected to the computer".)

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Copy, move, rename, delete files
  • Create directories
  • Create files
  • Enumerate files
  • Execute files
  • Get drive information
  • Get file information
  • Open and modify files
  • Log keystrokes and active window
  • Enumerate TCP and UDP connections
  • Enumerate network resources
  • Set TCP connection state
  • Lock workstation
  • Log off user
  • Restart/Reboot system
  • Display a message box
  • Perfrom port mapping
  • Enumerate processes
  • Get process information
  • Terminate processes
  • Enumerate registry keys
  • Create registry keys
  • Delete registry keys
  • Copy registry keys
  • Enumerate registry entries
  • Modify registry entries
  • Delete registry values
  • Screen capture
  • Delete services
  • Enumerate services
  • Get service information
  • Modify services
  • Start services
  • Perform remote shell
  • Connect to a database server and execute SQL statement
  • Host Telnet server

It connects to the following websites to send and receive information:

  • fuckchina.{BLOCKED}b.com
  • wmi.{BLOCKED}1.us

Dropping Routine

This backdoor drops the following files:

  • %User Temp%\RarSFX0\Nv.mp3
  • %User Temp%\RarSFX0\NvSmartMax.dll - also detected as BKDR_PLUGX.CA
  • %User Temp%\RarSFX0\Nv.exe
  • %System%\Nv.mp3 - (hidden)
  • %System%\NvSmartMax.dll - (hidden) also detected as BKDR_PLUGX.CA
  • %System%\Nv.exe - (hidden)

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

Information Theft

This backdoor accepts the following parameters:

  • -k

Other Details

This backdoor deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

9.700

VSAPI OPR PATTERN File:

10.617.00

VSAPI OPR PATTERN Date:

20 Feb 2014

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UPS
    • Security
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UPS
    • Enum
  • In HKEY_CLASSES_ROOT
    • FAST
  • In HKEY_LOCAL_MACHINE
    • FAST
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root
    • LEGACY_UPS

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.

RESTORE
  • Close Registry Editor.
  • Step 5

    Restore this modified registry value

    [ Learn More ]

    Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.

    • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UPS
      • From: ImagePath = ""%System%\Nv.exe" 2000"
        To: ImagePath = "%System%\ups.exe"
    • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UPS
      • From: Type = "110"
        To: Type = "10"
    • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UPS
      • From: Start = "2"
        To: Start = "3"
    • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UPS
      • From: ErrorControl = "0"
        To: ErrorControl = "1"
    • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UPS
      • From: DisplayName = "ups"
        To: DisplayName = "Uninterruptible Power Suply"
    • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UPS
      • From: ObjecName = "LocalSystem"
        To: ObjecName = "NT AUTHORITY\LocalSevice"
    • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UPS
      • From: Description = "ups"
        To: Description = "Manages an uninterruptible power supply (UPS) connected to the computer"

    Step 6

    Search and delete these folders

    [ 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.
    • %User Temp%\RarSFX0
    • %All Users Profile%\SxS

    Step 7

    Search and delete this file

    [ Learn More ]
    There may be some 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%\Nv.mp3
    • %System%\Nv.exe

    Step 8

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