Analysis by: RonJay Kristoffer Caragay
ALIASES:

Backdoor:Win32/Vawtrak.F (Microsoft); Win32/PSW.Papras.CP (ESET-NOD32); Trojan-PSW.Win32.Tepfer.ufql (Kaspersky); Backdoor/Win32.Vawtrak (AhnLab-V3)

 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: No

  • 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: 326,585 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 25 Jul 2014
Payload: Compromises system security, Steals information, Connects to URLs/IPs

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 files:

  • %All Users Profile%\Application Data\{random filename}.dat - detected also as BKDR_VAWTRAK.YJ
  • %ProgramData%\{random filename}.dat - detected also as BKDR_VAWTRAK.YJ (For Windows Vista above)

(Note: %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.. %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).)

It 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
{random filename} = "regsvr32.exe "%All Users Profile%\Application Data\{random filename}.dat""

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random filename} = "regsvr32.exe "%ProgramData%\{random filename}.dat"" (For Windows Vista above)

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_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\Microsoft\
Windows\CurrentVersion\Internet Settings
GlobalUserOffline = "0"

HKEY_CLASSES_ROOT\CLSID\{CLSID 1}
#cert = "31"

HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 1}
#cert = "31"

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

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

HKEY_CLASSES_ROOT\CLSID\{CLSID 2}
{CLSID 4} = "{hex values}"

HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 2}
{CLSID 4} = "{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://{domain name}/viewforum.php?f={value}&sid={value}
  • http://{domain name}/posting.php?mode=reply&f={value}&t={value}&sid={value}
  • http://{domain name}/posting.php?mode=post&f={value}&sid={value}

Information Theft

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

  • 32BitFtp
  • 3D-FTP
  • AceBIT
  • ALFTP
  • BitKinex
  • BlazeFtp
  • Bullet Proof FTP
  • ClassicFTP
  • CoffeeCup
  • COREFTP
  • Cryer
  • CuteFTP
  • CuteFTP 6 Home
  • CuteFTP 6 Professional
  • CuteFTP 7 Home
  • CuteFTP 7 Professional
  • CuteFTP 8 Home
  • CuteFTP 8 Professional
  • CuteFTP Lite
  • CuteFTP Pro
  • Cyberduck
  • DataDirBak
  • DeluxeFTP
  • Directory Opus
  • EasyFTP
  • ExpanDrive
  • Far
  • Far2
  • FFFTP
  • FileZilla
  • FlashFXP
  • Fling
  • FreshFTP
  • Frigate3
  • FTP Commander
  • FTP CONTROL
  • FTP Explorer
  • FTP Navigator
  • FTP Salt
  • FTP++.Link
  • FTPGetter
  • FTPInfo
  • FTPNow
  • FTPRush
  • FTPShell
  • FTPVoyager
  • Ghisler
  • Global Downloader
  • GoFTP
  • LeapFTP
  • LeechFTP
  • LinasFTP
  • Martin Prikryl
  • My FTP
  • NetDrive
  • NetSarang
  • NexusFile
  • Notepad++
  • NovaFTP
  • Odin
  • PuTTY
  • RhinoSoft
  • RimArts
  • Robo-FTP
  • SecureFX
  • SmartFTP
  • SoftX.org
  • Staff-FTP
  • TurboFTP
  • UltraFXP
  • Visicom Media
  • WebDrive
  • WinFTP
  • WinZip FTP
  • WS_FTP

It attempts to steal stored email credentials from the following:

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

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

  • Thunderbird
  • FastStone Browser
  • Epic Browser
  • Flock
  • K-Meleon
  • Firefox
  • SeaMonkey

NOTES:

where {domain name} can be any of the following URLs:

  • {BLOCKED}is.com
  • {BLOCKED}ng.com
  • {BLOCKED}rda.com
  • {BLOCKED}ka.com
  • {BLOCKED}nova.com
  • {BLOCKED}ka.com
  • {BLOCKED}ag.com
  • {BLOCKED}ixand.net
  • {BLOCKED}ad.com
  • {BLOCKED}lon.com
  • {BLOCKED}3.com
  • {BLOCKED}z.com
  • {BLOCKED}lpane.com

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

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

It checks for the presence of the following security-related directory:

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

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

  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

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.YJ

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 filename}.dat""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random filename} = "regsvr32.exe "%ProgramData%\{random filename}.dat"" (For Windows Vista above)
  • 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • GlobalUserOffline = "0"

Step 6

Search and delete files detected as BKDR_VAWTRAK.YJ

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.

Step 7

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

Step 8

The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.

  • 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}


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