Modified by: Rika Joi Gregorio
ALIASES:

Backdoor:Win32/Vawtrak.A(Microsoft), Trojan.Ransomlock.G(Symantec), Trojan-PWS.Win32.Tepfer(Ikarus), Win32/PSW.Papras.CP trojan(Eset)

 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

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

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 241,664 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 Oct 2013

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 and executes the following files:

  • %All Users Profile%\Application Data\{random file name}.dat - also detected as BKDR_VAWTRAK.PHP
  • %Program Data%\{random file name}.dat - also detected as BKDR_VAWTRAK.PHP for Windows Vista and 7 only

(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.)

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 file name} = "regsvr32.exe /s "%All Users Profile%\Application Data\{random file name}.dat""

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random file name} = "regsvr32.exe /s "%Program Data%\{random file name}.dat"" for Windows Vista and 7 only

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\AppDataLow\
{random key 1}

HKEY_CURRENT_USER\SOFTWARE\AppDataLow\
{random key 2}

It adds the following registry entries:

HKEY_CURRENT_USER\SOFTWARE\AppDataLow\
{random key 2}
{random} = "{random}"

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

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

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

Backdoor Routine

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

  • Keylog
  • Capture screenshots
  • Start process (iexplore.exe, firefox.exe, outlook.exe, explorer.exe, cmd.exe, taskmgr.exe)
  • Inject to process
  • Update itself
  • Download and execute files
  • List processes
  • Perform remote shell

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

  • http://{BLOCKED}elando.com/post.aspx?forumID={random digit}
  • http://{BLOCKED}elando.com/forumdisplay.php?fid={random digit}
  • http://{BLOCKED}ntofont.com/forumdisplay.php?fid={random digit}
  • http://{BLOCKED}ix.com/post.aspx?forumID={random digit}
  • http://{BLOCKED}ntofont.com/post.aspx?forumID={random digit}
  • http://{BLOCKED}kos.com/forumdisplay.php?fid=v
  • http://{BLOCKED}.{BLOCKED}.80.107/update?v={random digit}
  • http://{BLOCKED}kos.com/post.aspx?messageID={random digit}

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 gathers the following account information from any of the mentioned File Transfer Protocol (FTP) clients or file manager software:

  • Password
  • User ID
  • Server Type
  • Server Name
  • Port Number
  • Directory List

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

Other Details

This backdoor deletes itself after execution.

NOTES:

This backdoor 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
  • 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
  • f-secure
  • FRISK Software
  • G DATA
  • K7 omputing
  • Kaspersky Lab Setup Files
  • Kaspersky Lab
  • Lavasoft
  • Malwarebytes' Anti-Malware
  • Malwarebytes
  • McAfee.com
  • McAfee
  • 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
  • Zillya Antivirus

If any of the following were found, it creates a registry key and entry with the following information:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Safer\CodeIdentifiers\0\Paths\{random}
SaferFlags = 0
ItemData = {directory}\{folder name}

For example:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Safer\CodeIdentifiers\0\Paths\{random}
ItemData = %Program Files%\Trend Micro

It will 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: 9.300
FIRST VSAPI PATTERN FILE: 10.366.02
FIRST VSAPI PATTERN DATE: 26 Oct 2013
VSAPI OPR PATTERN File: 10.367.00
VSAPI OPR PATTERN Date: 27 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

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
    • {random key 1}
  • In HKEY_CURRENT_USER\SOFTWARE\AppDataLow
    • {random key 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\Internet Settings\Zones\3
    • 2500 = "3"
  • 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\Run
    • {random file name} = "regsvr32.exe /s "%All Users Profile%\Application Data\{random file name}.dat""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random file name} = "regsvr32.exe /s "%Program Data%\{random file name}.dat"" <i>for Windows Vista and 7 only</i>
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Safer\CodeIdentifiers\0\Paths\{random}
    • SaferFlags = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Safer\CodeIdentifiers\0\Paths\{random}
    • ItemData = "{directory}\{folder name}"

Step 5

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