BKDR_PLUGX.TOK

 Analysis by: Rika Joi Gregorio

 ALIASES:

Backdoor.Korplug(Symantec)

 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 does not have any downloading capability.

  TECHNICAL DETAILS

File Size:

593,920 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Mar 2014

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 files:

  • %Application Data%\{random letter}{random digits}{random letter}\contactlist.doc
  • %Application Data%\{random letter}{random digits}{random letter}\mpsvc.dll - also detected as BKDR_PLUGX.TOK

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

It drops and executes the following files:

  • %Application Data%\{random letter}{random digits}{random letter}\MsMpEng.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

It adds the following processes:

  • iexplore.exe
  • msiexec.exe

Its DLL component is injected to the following process(es):

  • executed MsMpEng.exe

It creates the following folders:

  • %Application Data%\{random letter}{random digits}{random letter}

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

It injects codes into the following process(es):

  • created iexplore.exe
  • created msiexec.exe

Autostart Technique

This backdoor drops the following shortcut pointing to its copy in the User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\DirectPlayLocalNetFile.lnk - points to %Application Data%\{random letter}{random digit}{random letter}\MsMpEng.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CLASSES_ROOT\MJ

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
YOSHIDA

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
YOSHIDA\Settings

It adds the following registry entries:

HKEY_CLASSES_ROOT\MJ
CLSID = "{CLSID}"

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/Shutdown 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 URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}.{BLOCKED}.59.193

Download Routine

This backdoor does not have any downloading capability.

NOTES:

Upon execution, this backdoor opens its dropped non-malicious file %Application Data%\{random letter}{random digit}{random letter}\contactlist.doc to hide its malicious routines from the user.

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.646.05

FIRST VSAPI PATTERN DATE:

06 Mar 2014

VSAPI OPR PATTERN File:

10.647.00

VSAPI OPR PATTERN Date:

07 Mar 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_CLASSES_ROOT
    • MJ
  • In HKEY_CURRENT_USER\Software
    • Local AppWizard-Generated Applications

Step 4

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.
  • %Application Data%\{random letter}{random digits}{random letter}

Step 5

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.
  • %User Startup%\DirectPlayLocalNetFile.lnk

Step 6

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