Analysis by: Jaime Benigno Reyes
ALIASES:

Backdoor:Win32/Vawtrak.F (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

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 does not have any propagation routine.

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

  TECHNICAL DETAILS

File Size: 285,064 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 01 Nov 2014
Payload: Connects to URLs/IPs, Compromises system security

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.

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
{malware filename} = "regsvr32.exe "{malware path}\{malware filename}.{malware extension name}""

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\{CLSID 1}

HKEY_CLASSES_ROOT\CLSID\{CLSID 2}

HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 1}

HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 2}

It adds the following registry entries:

HKEY_CLASSES_ROOT\CLSID\{CLSID 2}
{CLSID 4} = "{encrypted form of config data}"

HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 2}
{CLSID 4} = "{encrypted form of config data}"

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\{CLSID 1}
#cert = "{hex value}"

HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 1}
#cert = "{hex value}"

HKEY_CLASSES_ROOT\CLSID\{CLSID 2}
{CLSID 3} = "{hex value}"

HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 2}
{CLSID 3} = "{hex value}"

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

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

  • Receive config data it will use for its information stealing routine
  • 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

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{malicious domain}/viewforum.php?f={value}&sid={value}
  • http://{malicious domain}/posting.php?mode=reply&f={value}&t={value}&sid={value}
  • http://{malicious domain}/posting.php?mode=post&f={value}&sid={value}

Information Theft

This backdoor s configuration file contains the following information:

  • websites to monitor
  • URL source of the codes to use for web injects

It 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:
The malicious domains mentioned above are the following:

  • {BLOCKED}.{BLOCKED}.184.239
  • {BLOCKED}is.com
  • {BLOCKED}ng.com
  • {BLOCKED}rda.com
  • {BLOCKED}ka.com
  • {BLOCKED}.{BLOCKED}.192.106
  • {BLOCKED}nova.com
  • {BLOCKED}ka.com
  • {BLOCKED}.{BLOCKED}.192.110
  • {BLOCKED}ag.com
  • {BLOCKED}.{BLOCKED}.51.216
  • {BLOCKED}ixand.net
  • {BLOCKED}.{BLOCKED}.233.91
  • {BLOCKED}ad.com
  • {BLOCKED}lon.com
  • {BLOCKED}.{BLOCKED}.233.97
  • {BLOCKED}3.com
  • {BLOCKED}z.com
  • {BLOCKED}lpane.com

As of this writing, only {BLOCKED}ad.com is accessible.

It 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

It can only perform its intended routine once it is injected in the following processes:

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

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.700
VSAPI OPR PATTERN File: 11.253.00
VSAPI OPR PATTERN Date: 03 Nov 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.DSW

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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
    • {CLSID 1}
  • In HKEY_CLASSES_ROOT\CLSID
    • {CLSID 2}
  • In HKEY_CURRENT_USER\Software\Classes\CLSID
    • {CLSID 1}
  • In HKEY_CURRENT_USER\Software\Classes\CLSID
    • {CLSID 2}

Step 6

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
    • {malware filename} = "regsvr32.exe "{malware path}\{malware filename}.{malware extension name}""
  • 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"

Step 7

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