BKDR_VAWTRAK.FI

April 04, 2014
 Analysis by: Adrian Cofreros
 ALIASES:

PWS:Win32/Delf.EM(Microsoft),TR/Vawtrak.A.120(Antivir),a variant of Win32/Kryptik.BYCI trojan(NOD32),

 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:

Dropped by other malware, Downloaded from the Internet

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 is injected into all running processes to remain memory resident.

It does not have any propagation routine.

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

  TECHNICAL DETAILS

File Size:

229,632 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

01 Apr 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 is injected into all running processes to remain memory resident.

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

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\AppDataLow\
{GUID 1}

HKEY_CURRENT_USER\Software\AppDataLow\
{GUID 2}

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_CURRENT_USER\Software\AppDataLow\
{GUID 2}
{GUID} = "{hex values}"

Propagation

This backdoor does not have any propagation routine.

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

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

  • http://{BLOCKED}ally.com/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}ix.com/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}ag.com/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}d.com/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}on.com/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}.{BLOCKED}.32.80/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}.{BLOCKED}.32.67/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}.{BLOCKED}.233.38/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}lon.com/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}.{BLOCKED}.233.80/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}z.com/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}lpane.com/forumdisplay.php?fid={random digits}
  • http://{BLOCKED}.{BLOCKED}.233.38/update?v={value}
  • http://{any of url above}/post.aspx?messageID={randomdigits}
  • http://{BLOCKED}lpane.com/forumdisplay.php?fid={random digits}

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:

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

  • %System Root%:\Documents and Settings\NetworkService\Local Settings\Application Data\F-SecureF-Secure Internet Security
  • 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 registries 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}"
 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

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

Restart in Safe Mode

[ 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_CURRENT_USER\Software\AppDataLow
    • {GUID 1}
  • In HKEY_CURRENT_USER\Software\AppDataLow
    • {GUID 2}

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\CurrentVersion\Run
    • {malware file name} = "regsvr32.exe "{malware path}\{malware file name}.{malware extension}""
  • 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 5

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