BKDR_WOLYX.TYT

October 09, 2012
 Analysis by: Jasen Sumalapao
 Modified by: Jed Valderama
 ALIASES:

Trojan-PWS.Win32.Hangame.cl (Ikarus)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware

This malware checks if it is injected to certain processes.

It checks if it is injected to certain Web browsers.

It is capabable of executing certain commands.

This backdoor may be dropped by other malware.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

197,352 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

15 Aug 2012

Payload:

Connects to URLs/IPs, Compromises system security, Drops files

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_MDROP.TYT
  • TROJ_HUPIGO.RUD

Installation

This backdoor drops a copy of itself in the following folders using different file names:

  • %User Temp\{Random filename and extension}

It drops the following component file(s):

  • %Program Files%\Common Files\Microsoft Shared\OFFICE12\MSO32.DLL - detected as BKDR_WOLYX.TYT

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

It creates the following folders:

  • %System Root%\Users\Public\{AFAFB2EE-837C-4EA5-B933-998F94AEC654}
  • %System Root%\ProgramData\{AFAFB2EE-837C-4EA5-B933-998F94AEC654}
  • %Windows%\TEMP\TEMP
  • %Program Files%\Common Files\Microsoft Shared\OFFICE12

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

Other System Modifications

This backdoor adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\Session Manager
PendingFileRenameOperations = %User Temp\{Random filename and extension}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinSock2\mswsock32
1001 = %SystemRoot%\system32\mswsock.dll

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinSock2\mswsock32
1002 = %SystemRoot%\system32\mswsock.dll

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinSock2\mswsock32
1003 = %SystemRoot%\system32\mswsock.dll

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinSock2\mswsock32
1004 = %SystemRoot%\system32\rsvpsp.dll

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinSock2\mswsock32
1005 = %SystemRoot%\system32\rsvpsp.dll

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinSock2\mswsock32
PathName = %Program Files%\Common Files\Microsoft Shared\OFFICE12\MSO32.DLL

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.172.177

It deletes itself after execution.

NOTES:

It checks if it is injected to the following processes:

  • 360sd.exe
  • 360rp.exe
  • 360safe.exe
  • 360tray.exe
  • avp.exe
  • dsmain.exe
  • dumprep.exe

It checks if it is injected to the following Web browsers:

  • firefox.exe
  • maxthon.exe
  • ttraveler.exe
  • theworld.exe

It is capabable of the following commands:

  • Command Shell
  • Create/Delete Directories
  • Create/Read/Delete Files
  • Get System Info
  • Create/Terminate Process
  • Key Logging
  • Take ScreenShot

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.326.07

FIRST VSAPI PATTERN DATE:

15 Aug 2012

VSAPI OPR PATTERN File:

9.327.00

VSAPI OPR PATTERN Date:

16 Aug 2012

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware/grayware files that dropped/downloaded BKDR_WOLYX.TYT

    • TROJ_MDROP.TYT
    • TROJ_HUPIGO.RUD

Step 3

Restart in Safe Mode

[ Learn More ]

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager
    • PendingFileRenameOperations = "%User Temp\{Random filename and extension}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\mswsock32
    • 1001 = "%SystemRoot%\system32\mswsock.dll"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\mswsock32
    • 1002 = "%SystemRoot%\system32\mswsock.dll"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\mswsock32
    • 1003 = "%SystemRoot%\system32\mswsock.dll"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\mswsock32
    • 1004 = "%SystemRoot%\system32\rsvpsp.dll"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\mswsock32
    • 1005 = "%SystemRoot%\system32\rsvpsp.dll"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\mswsock32
    • PathName = "%Program Files%\Common Files\Microsoft Shared\OFFICE12\MSO32.DLL"

Step 5

Search and delete these folders

[ 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.
  • %System Root%\Users\Public\{AFAFB2EE-837C-4EA5-B933-998F94AEC654}
  • %System Root%\ProgramData\{AFAFB2EE-837C-4EA5-B933-998F94AEC654}
  • %Windows%\TEMP\TEMP
  • %Program Files%\Common Files\Microsoft Shared\OFFICE12

Step 6

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