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TROJ_HIDEFIL.USK29VC

October 13, 2012
 ALIASES:

Worm:Win32/Vobfus.gen!O (Microsoft); VBObfus.bv (McAfee); W32.Changeup (Symantec); Worm.Win32.WBNA.bjf, Worm.Win32.WBNA.bjf (Kaspersky); Trojan.Win32.Generic!SB.0 (Sunbelt); Gen:Variant.VBKrypt.23 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size:

241,664 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 Jul 2012

Arrival Details

This Trojan 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 Trojan creates the following folders:

  • %User Profile%\Application Data\F0BDF
  • %Program Files%\LP
  • %Program Files%\LP\0D2F

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /G"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /r"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /O"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /R"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /P"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /k"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /J"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /Y"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /t"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /W"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /d"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /A"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /V"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /S"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /g"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /e"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /T"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /h"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /u"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /y"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /B"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /w"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /x"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rewoq = "%User Profile%\rewoq.exe /D"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /F"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /o"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /i"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /z"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /S"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /p"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /v"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /B"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /e"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /N"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /Y"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /s"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /G"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /Q"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /M"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /I"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /a"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /h"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
dhgaz = "%User Profile%\dhgaz.exe /J"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
056.exe = "%Program Files%\LP\0D2F\056.exe"

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\.netbt

Other System Modifications

This Trojan deletes the following files:

  • %User Profile%\rewoq.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\WinRAR

HKEY_CURRENT_USER\Software\2387fd88

HKEY_LOCAL_MACHINE\Software\Classes\
Interface\{5171463b-76a3-9033-2274-75c8f0a0edb6}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

HKEY_CURRENT_USER\Software\WinRAR
HWID = "{random values}"

HKEY_CURRENT_USER\Software\WinRAR
Client Hash = "{random values}"

HKEY_CURRENT_USER\Software\2387fd88
qid = "6f6d16b3"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{5171463b-76a3-9033-2274-75c8f0a0edb6}
u = "bc"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.netbt
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.netbt
Start = "3"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.netbt
ImagePath = "\?"

HKEY_CURRENT_USER\Software\2387fd88
u = "bc"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wscsvc
Start = "3"

(Note: The default value data of the said registry entry is 2.)

Dropping Routine

This Trojan drops the following files:

  • %Program Files%\LP\0D2F\056.exe
  • %Program Files%\LP\0D2F\1.tmp
  • U
  • L
  • ACPI#PNP0303#2&da1a3ff&0\L\suianxvn
  • ACPI#PNP0303#2&da1a3ff&0\@
  • @
  • X

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

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://chicken.{BLOCKED}{BLOCKED}.lt:30501/a

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services
    • .netbt
  • In HKEY_CURRENT_USER\Software
    • WinRAR
  • In HKEY_CURRENT_USER\Software
    • 2387fd88
  • In HKEY_LOCAL_MACHINE\Software\Classes\Interface
    • {5171463b-76a3-9033-2274-75c8f0a0edb6}

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
    • rewoq = "%User Profile%\rewoq.exe /G"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /r"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /O"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /R"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /P"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /k"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /J"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /Y"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /t"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /W"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /d"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /A"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /V"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /S"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /g"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /e"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /T"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /h"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /u"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /y"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /B"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /w"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /x"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rewoq = "%User Profile%\rewoq.exe /D"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /F"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /o"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /i"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /z"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /S"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /p"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /v"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /B"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /e"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /N"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /Y"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /s"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /G"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /Q"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /M"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /I"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /a"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /h"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • dhgaz = "%User Profile%\dhgaz.exe /J"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • 056.exe = "%Program Files%\LP\0D2F\056.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "0"
  • In HKEY_CURRENT_USER\Software\WinRAR
    • HWID = "{random values}"
  • In HKEY_CURRENT_USER\Software\WinRAR
    • Client Hash = "{random values}"
  • In HKEY_CURRENT_USER\Software\2387fd88
    • qid = "6f6d16b3"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{5171463b-76a3-9033-2274-75c8f0a0edb6}
    • u = "bc"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.netbt
    • Type = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.netbt
    • Start = "3"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.netbt
    • ImagePath = "\?"
  • In HKEY_CURRENT_USER\Software\2387fd88
    • u = "bc"

Step 5

Restore this modified 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\ControlSet001\Services\wscsvc
    • From: Start = "3"
      To: Start = ""2""

Step 6

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %Program Files%\LP\0D2F\056.exe
  • %Program Files%\LP\0D2F\1.tmp
  • U
  • L
  • ACPI#PNP0303#2&da1a3ff&0\L\suianxvn
  • ACPI#PNP0303#2&da1a3ff&0\@
  • @
  • X

Step 7

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.
  • %User Profile%\Application Data\F0BDF
  • %Program Files%\LP
  • %Program Files%\LP\0D2F

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_HIDEFIL.USK29VC. 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 9

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Profile%\rewoq.exe


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