Analysis by: Adrian Cofreros
ALIASES:

Win32/Wisp.T trojan(NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • 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.

It does not have any propagation routine.

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

  TECHNICAL DETAILS

File Size: 26,624 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 19 Jul 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:

  • %User Temp%\pfile.dat -encrypted content of pfilede.dat
  • %User Temp%\put.jpg - to be uploaded on the C&C
  • %User Temp%\pfilede.dat - containing information and details done by the program(like downloading of file, proxy, shell executed)
  • %User Temp%\tref.tmp - part of the processing contents
  • %User Temp%\gfilede.dat - part of the processing contents

(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.)

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

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

  • Download file
  • Execute shell commands
  • Upload file
  • Terminate Process

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

  • http://{BLOCKED}l.{BLOCKED}dolphin.com/asp/allow_get.asp?name=sunset.jpg&hostname={hostname}-{IP address of affected system}ff
  • http://{BLOCKED}l.{BLOCKED}dolphin.com/asp/allow_put.asp?type=put.jpg&hostname={hostname}-{IP address of the affected system}ff

As of this writing, the said sites are inaccessible.

Download Routine

This backdoor saves the files it downloads using the following names:

  • %User Temp%\gfile.dat

(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.)

Information Theft

This backdoor gathers the following data:

  • Host Name
  • IP address of affected Machine
  • Proxy server settings(registry,file:prefs.js)
  • Password stored by Internet Explorer

NOTES:

It may connect using proxy by retrieving the registry:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
Proxyserver={contents of the proxy}

Depending on which is available for proxy settings, it may also connect using proxy by retrieving it on the following file:

  • prefs.js

During its execution it may drop or delete its dropped files.

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.700

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

Scan your computer with your Trend Micro product and note files detected as BKDR_WISP.DUK

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Search and delete the file detected as BKDR_WISP.DUK

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 6

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 Temp%\pfile.dat
  • %User Temp%\put.jpg
  • %User Temp%\pfilede.dat
  • %User Temp%\tref.tmp
  • %User Temp%\gfilede.dat
  • %User Temp%\gfile.dat

Step 7

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