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BKDR_VAWTRAK.YZN

September 05, 2014
 Modified by: Rhena Inocencio
 ALIASES:

Backdoor:Win32/Vawtrak (Microsoft), Trojan-Spy.Win32.SpyEyes.aprk (Kaspersky)

 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:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


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 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:

337,312 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Jun 2014

Payload:

Compromises system security, Steals information

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 component file(s):

  • %ProgramData%\{random folder name}\{random filename}.dat - BKDR_VAWTRAK.YAB
  • %All Users Profile%\Application Data\{random folder name}\{random filename}.dat - BKDR_VAWTRAK.YAB

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This is usually C:\ProgramData in Windows Vista and 7, or C:\Program Files on Windows 2000, XP (32-bit), and Server 2003, or C:\Program Files (x86) on Windows XP (64-bit).. %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 injects codes into the following process(es):

  • explorer.exe
  • chrome.exe
  • firefox.exe
  • iexplore.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random filename} = "regsvr32.exe "%ProgramData%\{random folder name}\{random filename}.dat""

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random filename} = "regsvr32.exe "%All Users Profile%\Application Data\{random folder name}\{random filename}.dat""

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\{GUID}

HKEY_CURRENT_USER\Software\Classes\
CLSID\{GUID}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
NoProtectedModeBanner = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
TabProcGrowth = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
2500 = "3"

HKEY_CLASSES_ROOT\CLSID\{GUID}
#cert = "{hex value}"

HKEY_CURRENT_USER\Software\Classes\
CLSID\{GUID}
#sd = "{hex value}"

HKEY_CLASSES_ROOT\CLSID\{GUID}
{GUID} = "{hex value}"

Backdoor Routine

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

  • Update itself
  • Download and execute files
  • List active processes
  • Perform remote shell
  • Execute file
  • Keylog
  • Capture Screenshot
  • Monitor sound
  • Start/Stop process (iexplore.exe, firefox.exe, outlook.exe, explorer.exe, cmd.exe, taskmgr.exe)
  • Inject to process
  • Get clipboard data
  • Receive config data which is saved on registry

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

  • {BLOCKED}kls.com
  • {BLOCKED}cda.com
  • {BLOCKED}cda.net

Information Theft

This backdoor attempts to steal stored account information used in the following installed File Transfer Protocol (FTP) clients or file manager software:

  • 3D-FTP
  • AceBIT
  • AceFTP
  • ALFTP
  • BitKinex
  • BlazeFtp
  • BulletProof FTP
  • ClassicFTP
  • CoffeeCup Software
  • Cyberduck
  • DeluxeFTP
  • Directory Opus
  • EasyFTP
  • ExpanDrive
  • FarManager
  • FFFTP
  • FileZilla
  • FlashFXP
  • Fling FTP
  • FreshFTP
  • FTP Commander
  • FTP Explorer
  • FTP Navigator
  • FTPGetter
  • FTPNow
  • FTPRush
  • FTPShell
  • FTPVoyager
  • FTPWare
  • GlobalSCAPE CuteFTP 6 Home
  • GlobalSCAPE CuteFTP 7 Home
  • GlobalSCAPE CuteFTP 8 Home
  • GlobalSCAPE CuteFTP
  • GlobalSCAPE CuteFTP 8 Professional
  • GlobalSCAPE CuteFTP 6 Professional
  • GlobalSCAPE CuteFTP 7 Professional
  • GlobalSCAPE CuteFTP Lite
  • GlobalSCAPE CuteFTP Pro
  • GoFTP
  • LeapFTP
  • LeechFTP
  • LinasFTP
  • My FTP
  • NetDrive
  • NetSarang
  • NexusFile
  • NovaFTP
  • PuTTY
  • RhinoSoft
  • Robo-FTP
  • SecureFX
  • SmartFTP
  • SoftX FTP
  • Staff-FTP
  • Titan FTP
  • Total Commander
  • TurboFTP
  • UltraFXP
  • WinFTP
  • WinSCP
  • WS_FTP

It attempts to steal stored email credentials from the following:

  • IncrediMail
  • Outlook
  • PocoMail
  • The Bat!
  • Thunderbird
  • Windows Live Mail
  • Windows Mail

It attempts to get stored information such as user names, passwords, and hostnames from the following browsers:

  • Epic Browser
  • Flock
  • K-Meleon
  • Mozilla Firefox
  • SeaMonkey

NOTES:

This backdoor checks for the presence of the following security-related directories in %Program Files% and %All Users Profile%\Application Data:

  • a-squared Anti-Malware
  • a-squared HiJackFree
  • Agnitum
  • Alwil Software
  • AnVir Task Manager
  • ArcaBit
  • AVAST Software
  • AVG
  • avg8
  • Avira GmbH
  • Avira
  • BitDefender
  • BlockPost
  • Common Files\Doctor Web
  • Common Files\G DATA
  • Common Files\P Tools
  • Common Files\Symantec Shared
  • DefenseWall
  • DefenseWall HIPS
  • Doctor Web
  • DrWeb
  • ESET
  • f-secure
  • FRISK Software
  • G DATA
  • K7 omputing
  • Kaspersky Lab Setup Files
  • Kaspersky Lab
  • Lavasoft
  • Malwarebytes
  • Malwarebytes' Anti-Malware
  • McAfee
  • McAfee.com
  • Microsoft Security Client
  • Microsoft Security Essentials
  • Microsoft\Microsoft Antimalware
  • Norton AntiVirus
  • Online Solutions
  • P Tools Internet Security
  • P Tools
  • Panda Security
  • Positive Technologies
  • Sandboxie
  • Security Task Manager
  • Spyware Terminator
  • Sunbelt Software
  • Symantec
  • Trend Micro
  • UAenter
  • Vba32
  • Xore
  • Zillya Antivirus

Once it finds one of the AV installations mentioned above, it then creates the following registry entries to force the AV installation to run under restricted user privileges:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Safer\
CodeIdentifiers\0\Paths\{generated GUID for the AV software}
ItemData = "{AV software path}"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Safer\
CodeIdentifiers\0\Paths\{generated GUID for the AV software}
SaferFlags ="0"

The configuration data that is received commonly contains the banking and credit card institutions in which it monitors. However, as of this writing, there was no response from the C&C server

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.854.04

FIRST VSAPI PATTERN DATE:

10 Jun 2014

VSAPI OPR PATTERN File:

10.855.00

VSAPI OPR PATTERN Date:

11 Jun 2014

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_VAWTRAK.YZN

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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
    • {random filename} = "regsvr32.exe %All Users Profile%\Application Data\{random folder name}\{random filename}.dat""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random filename} = "regsvr32.exe "%ProgramData%\{random folder name}\{random filename}.dat""
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • NoProtectedModeBanner = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • TabProcGrowth = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    • 2500 = "3"
  • In HKEY_CLASSES_ROOT\CLSID\{GUID}
    • #cert = "{hex value}"
  • In HKEY_CURRENT_USER\Software\Classes\CLSID\{GUID}
    • #sd = "{hex value}"
  • In HKEY_CLASSES_ROOT\CLSID\{GUID}
    • {GUID} = "{hex value}"

Step 6

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_CLASSES_ROOT\CLSID
    • {GUID}
  • In HKEY_CURRENT_USER\Software\Classes\CLSID
    • {GUID}

Step 7

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