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TROJ64_VBUZKY.A

October 21, 2013
 Analysis by: Rhena Inocencio
 ALIASES:

Trojan-Dropper.Win64.Vabushky.a (Kaspersky), Trojan.Ransomcrypt.E (Symantec), Win64/Vabushky.A trojan (ESET), Troj/Vabshky-A (Sophos)

 PLATFORM:

Windows XP (64-bit), Windows Vista (64-bit), Windows 7 (64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It injects its dropped file/component to specific processes.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE, DLL, SYS

Memory Resident:

Yes

Initial Samples Received Date:

08 Oct 2013

Payload:

Steals information, Connects to URLs/IPs, Displays graphics/image

Arrival Details

This Trojan 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 Trojan drops the following component file(s):

  • %User Temp%\dll.dll - also detected as TROJ64_VBUZKY.A
  • %System%\vBszKyhVp.dll - also detected as TROJ64_VBUZKY.A

(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.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • vBszKyhV

It injects its dropped file/component to the following processes:

  • svchost.exe
  • winlogon.exe
  • explorer.exe

Autostart Technique

This Trojan 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 entries:

HKEY_LOCAL_MACHINEsystem\currentcontrolset\services\
vBszKyhV
ImagePath = "%system%\drivers\vBszKyhV2.sys"

Other System Modifications

This Trojan modifies the following file(s):

  • appends .crypted to the encrypted files

It adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\vBszKyhV

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}.{BLOCKED}.112.86/b7cc7b7b-7502-4eec-8a10-2776b43e1051
  • http://{BLOCKED}.{BLOCKED}.112.86/a614ef1c-a9c8-48ad-911f-e44cb191c5af
  • http://{BLOCKED}.{BLOCKED}.112.86/b273e158-8982-47e3-b47f-6e5b280920ee

It saves the files it downloads using the following names:

  • %system%\drivers\vBszKyhV2.sys - also detected as TROJ64_VBUZKY.A
  • vBszKyhV1.exe - also detected as TROJ64_VBUZKY.A
  • vBszKyhV2.exe - also detected as TROJ64_VBUZKY.A
  • vBszKyhV.dll - also detected as TROJ64_VBUZKY.A

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Information Theft

This Trojan gathers the following data:

  • OS Version
  • Screen resolution
  • File versions of the follownig files:
    • win32k.sys
    • ntoskrnl.exe
    • ntkrnlpa.exe
    • ntkrnlmp.exe
    • ntkrpamp.exe

Stolen Information

This Trojan sends the gathered information via HTTP POST to the following URL:

  • http://{BLOCKED}.{BLOCKED}.93.16:9007/ar.do
  • http://{BLOCKED}.{BLOCKED}.93.16:9007/fv.do

Other Details

This Trojan encrypts files with the following extensions:

  • avi
  • wmv
  • aaf
  • 3gp
  • asf
  • avchd
  • dsh
  • flv
  • m1v
  • m2v
  • fla
  • flr
  • sol
  • m4v
  • mkv
  • wrap
  • mng
  • mov
  • mpeg
  • mpg
  • mpe
  • mp4
  • mxf
  • roq
  • nsv
  • ogg
  • rm
  • svi
  • smi
  • swf

NOTES:

This Trojan downloads the lock screen image from any of the following URLs depending on the system's screen resolution:

  • http://{BLOCKED}.{BLOCKED}.112.86/en/768x1024.bmp.gz
  • http://{BLOCKED}.{BLOCKED}.112.86/en/1024x768.bmp.gz
  • http://{BLOCKED}.{BLOCKED}.112.86/en/1152x864.bmp.gz
  • http://{BLOCKED}.{BLOCKED}.112.86/en/1280x800.bmp.gz
  • http://{BLOCKED}.{BLOCKED}.112.86/en/1280x1024.bmp.gz
  • http://{BLOCKED}.{BLOCKED}.112.86/en/1366x768.bmp.gz

It attempts to use Shell_TrayWnd injection. It enables TESTSIGNING option of Windows 7. It then restarts the system after execution of all routines.

It displays the following lock screen image:

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.328.05

FIRST VSAPI PATTERN DATE:

08 Oct 2013

VSAPI OPR PATTERN File:

10.329.00

VSAPI OPR PATTERN Date:

08 Oct 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

Identify and delete files detected as TROJ64_VBUZKY.A using either the Startup Disk or Recovery Console

[ 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\Software
    • vBszKyhV
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • vBszKyhV

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ64_VBUZKY.A. 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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