Analysis by: Janus Agcaoili

 PLATFORM:

Windows

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

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This spyware 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 then deletes itself afterward.

  TECHNICAL DETAILS

File Size: 1,060,352 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 27 May 2016

Arrival Details

This spyware 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 spyware drops a copy of itself in the following folders using different file names:

  • %AppDataLocal%\Microsoft\Windows\bthserv.exe
  • %User Profile%\Music\taskhost.exe

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It drops the following files:

  • %User Profile%\Documents\New Text Document.txt
  • %All Users Profile%\Mails.txt
  • %All Users Profile%\Browsers.txt
  • %User Temp%\Av.dmp

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.. %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.)

It drops and executes the following files:

  • %AppDataLocal%\Microsoft\Windows\BsBhvScan.exe

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

It adds the following processes:

  • %Windows%\Microsoft.NET\Framework\v2.0.50727\InstallUtil.exe

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It executes then deletes itself afterward.

It terminates the execution of the copy it initially executed and executes the copy it drops instead.

Autostart Technique

This spyware creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
Load = "%AppDataLocal%\Microsoft\Windows\BsBhvScan.exe"

Other Details

This spyware connects to the following possibly malicious URL:

  • http://www.{BLOCKED}e.com/uniteadmin/post.php?type=notification&machinename={machine name}&machinetime={time}

It does the following:

  • Sets a windows hook on the created process:
    • InstallUtil.exe

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.552.03
FIRST VSAPI PATTERN DATE: 27 May 2016
VSAPI OPR PATTERN File: 12.553.00
VSAPI OPR PATTERN Date: 28 May 2016

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 NT\CurrentVersion\Windows
    • Load = "%AppDataLocal%\Microsoft\Windows\BsBhvScan.exe"

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 Profile%\Documents\New Text Document.txt
  • %All Users Profile%\Mails.txt
  • %All Users Profile%\Browsers.txt
  • %User Temp%\Av.dmp
  • %AppDataLocal%\Microsoft\Windows\bthserv.exe
  • %User Profile%\Music\taskhost.exe
  • %AppDataLocal%\Microsoft\Windows\BsBhvScan.exe

Step 6

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