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BKDR_PLUGX.RJG

June 17, 2013
 Analysis by: Rika Joi Gregorio
 ALIASES:

a variant of Win32/Korplug.AK trojan(Eset), Win32.SuspectCrc(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:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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

  TECHNICAL DETAILS

File Size:

428,033 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

14 Jun 2013

Arrival Details

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

Installation

This backdoor drops the following files:

  • %All Users Profile%\¦++=+ñ¦G.doc
  • %User Temp%\PDH\PDH.dll
  • %User Temp%\PDH\PDH.pak

(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 drops and executes the following files:

  • %User Temp%\PDH\QQBrowserUpdateService.exe

(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.)

It creates the following folders:

  • %User Temp%\PDH

(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.)

Autostart Technique

This backdoor 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\QQBrowser Software Updater

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CLASSES_ROOT\FAST

HKEY_CURRENT_USER\Software\WinRAR SFX

It adds the following registry entries:

HKEY_CLASSES_ROOT\FAST
CLSID = "{random values}"

HKEY_CURRENT_USER\Software\WinRAR SFX
C%%Documents and Settings%All Users% = "%All Users Profile%\" (for Windows XP and lower versions)

HKEY_CURRENT_USER\Software\WinRAR SFX
C%%ProgramData% = "%ProgramData%\" (for Windows Vista and 7 only)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}t.{BLOCKED}ok.com:443/update?id=000f7d48

It opens the following files:

  • %All Users Profile%\¦++=+ñ¦G.doc

(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 adds and runs the following services:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\QQBrowser Software Updater
ImagePath = ""%User Temp%\PDH\QQBrowserUpdateService.exe" 200 0"

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.984.07

FIRST VSAPI PATTERN DATE:

16 Jun 2013

VSAPI OPR PATTERN File:

9.985.00

VSAPI OPR PATTERN Date:

17 Jun 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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • QQBrowser Software Updater
  • In HKEY_CLASSES_ROOT
    • FAST
  • In HKEY_CURRENT_USER\Software
    • WinRAR SFX

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.
  • %User Temp%\PDH

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.
  • %All Users Profile%\¦++=+ñ¦G.doc

Step 6

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