Modified by: Homer Pacag
ALIASES:

Backdoor:Win32/Plugx.L (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This backdoor may arrive bundled with malware packages as a malware component.

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 88,576 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 23 Jul 2015
Payload: Steals information

Arrival Details

This backdoor may arrive bundled with malware packages as a malware component.

Installation

This backdoor drops the following component file(s):

  • %User Temp%\starter.exe - deleted after
  • %User Temp%\splash_screen.dll - deleted after
  • %User Temp%\splash_screen.dll.sx deleted after
  • %ProgramData%\starter\starter.exe - non-malicious file used to load DLL component
  • %ProgramData%\starter\splash_screen.dll - also detected as BKDR_PLUGX.DUKNJ; used to load file with malicious code
  • %ProgramData%\starter\hfxpttdyumuzyovm - file containing malicious code

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKCU\Software\Microsoft\
Windows\CurrentVersion\Run
oDQgxcRpBV = %ProgramData%\starter\starter.exe

Backdoor Routine

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

  • Manage files, registries, services and directories
  • Log keystrokes and active window
  • Restart/Reboot/Shutdown system
  • Enumerate processes
  • Terminate processes
  • Get drive information
  • Enumerate network resources
  • Set TCP connection state
  • Lock workstation
  • Display a message box
  • Perform port mapping
  • Capture screen
  • Perform remote shell

NOTES:

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

  • http://web.{BLOCKED}rat.com:443

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.808.04
FIRST VSAPI PATTERN DATE: 23 Jul 2015
VSAPI OPR PATTERN File: 11.808.05
VSAPI OPR PATTERN Date: 23 Jul 2015

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

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.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • oDQgxcRpBV = %ProgramData%\starter\starter.exe

Step 5

Search and delete these components

[ Learn More ]
There may be some components 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.  
  • %ProgramData%\starter\starter.exe
  • %ProgramData%\starter\splash_screen.dll
  • %ProgramData%\starter\hfxpttdyumuzyovm

Step 6

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