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TROJ_SKINTRIM.SM

July 25, 2013
 ALIASES:

TrojanDownloader:Win32/Wintrim.BX (Microsoft); Skintrim.gen.h (McAfee); Trojan Horse (Symantec); Trojan-Downloader.Win32.Lipler.zht (Kaspersky); Trojan-Downloader.Win32.Wintrim.bxa (v) (Sunbelt); Trojan.Generic.2531285 (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:

881,155 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Sep 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:

  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\Wilbert
  • %User Profile%\LOCALS~1
  • %User Temp%\nsc3.tmp
  • %Program Files%\InternetGameBox
  • %Program Files%\InternetGameBox\ressources
  • %Program Files%\InternetGameBox\skins
  • %Start Menu%\Programs\InternetGameBox
  • ressources
  • ressources\favoris
  • %Program Files%\InternetGameBox\ressources\favoris

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.)

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
uucbcq = "%Application Data%\uucbcq.exe uucbcq"

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\nsn1.tmp
  • %User Temp%\nsc3.tmp

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\IGB

HKEY_LOCAL_MACHINE\Software\IGB

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
InternetGameBox

HKEY_CURRENT_USER\Software\fcn

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
uucbcq

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\IGB
grpid = "191"

HKEY_CURRENT_USER\Software\IGB
grpid = "191"

HKEY_LOCAL_MACHINE\SOFTWARE\IGB
InstallOpt1 = "1"

HKEY_CURRENT_USER\Software\IGB
InstallOpt1 = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\IGB
installdt = "20090109"

HKEY_CURRENT_USER\Software\IGB
installdt = "20090109"

HKEY_CURRENT_USER\Software\IGB
uai = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\IGB
dl_lg = "es"

HKEY_CURRENT_USER\Software\IGB
dl_lg = "es"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
InternetGameBox
DisplayName = "InternetGameBox "

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
InternetGameBox
UninstallString = "%Program Files%\InternetGameBox\uninst.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
InternetGameBox
UninstallString2 = "%Program Files%\InternetGameBox\uninst.exe /S"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
InternetGameBox
DisplayIcon = "%Program Files%\InternetGameBox\InternetGameBox.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
InternetGameBox
URLInfoAbout = "http://www.{BLOCKED}etgamebox.com"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
InternetGameBox
Publisher = "OOO «Favorit»"

HKEY_LOCAL_MACHINE\SOFTWARE\IGB
Installer Language = "1033"

HKEY_CURRENT_USER\Software\fcn
gid = "191"

HKEY_CURRENT_USER\Software\fcn
cnid = "lwvtiFTmRl2lmB57PE3kjg"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
uucbcq
DisplayName = "Favorit"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
uucbcq
UninstallString = "%Application Data%\uucbcq.exe -uninstall"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
uucbcq
NoRemove = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
uucbcq
NoModify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
uucbcq
NoRepair = "1"

HKEY_CURRENT_USER\Software\fcn
idt = "201209241539"

HKEY_LOCAL_MACHINE\SOFTWARE\IGB
bnrid = "672125"

It modifies the following registry entries:

HKEY_CURRENT_USER\SessionInformation
ProgramCount = "3"

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

HKEY_CURRENT_USER\SessionInformation
ProgramCount = "1"

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

HKEY_CURRENT_USER\SessionInformation
ProgramCount = "2"

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

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\nsn2.tmp
  • %User Temp%\nsc3.tmp\LangDLL.dll
  • %User Temp%\nsc3.tmp\ioSpecial.ini
  • %User Temp%\nsc3.tmp\modern-wizard.bmp
  • %User Temp%\nsc3.tmp\modern-header.bmp
  • %User Temp%\nsc3.tmp\InstallOptions.dll
  • %Application Data%\uucbcq.exe
  • %Program Files%\InternetGameBox\InternetGameBox.exe
  • %Program Files%\InternetGameBox\ressources\configv2_fr.xml
  • %Program Files%\InternetGameBox\ressources\configv2_en.xml
  • %Program Files%\InternetGameBox\ressources\configv2_es.xml
  • %Program Files%\InternetGameBox\skins\skinv2.skn
  • %Program Files%\InternetGameBox\language
  • %Start Menu%\Programs\InternetGameBox\InternetGameBox.lnk
  • %Start Menu%\Programs\InternetGameBox\Uninstall.lnk
  • %Desktop%\InternetGameBox.lnk
  • %Program Files%\InternetGameBox\uninst.exe
  • %Application Data%\uucbcq.dat
  • %Application Data%\uucbcq_navps.dat
  • %User Temp%\uucbcqpi.tmp
  • %Application Data%\uucbcq_m2s.xml
  • %Application Data%\uucbcq_m2s.zl
  • %Application Data%\uucbcq_s2m.zl
  • %Application Data%\uucbcq_s2m.xml
  • %User Temp%\uucbcqup.tmp
  • %Application Data%\uucbcq_navtmp.dat
  • %Application Data%\uucbcq_navup.dat
  • %User Temp%\uucbcqpic.tmp
  • ressources\favoris\defaultv2.swf
  • %Program Files%\InternetGameBox\ressources\AttenteOn.html
  • %Program Files%\InternetGameBox\ressources\AttenteOff.html

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista and 7.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://updates.{BLOCKED}-network.comsa/cpi.php?{random characters}
  • http://updates.{BLOCKED}-network.comsa/receive_data.php?tcpc=72031
  • http://updates.{BLOCKED}-network.combinaries/bin.php?id=0&up=1&fd=1&tcpc=77281
  • http://updates.{BLOCKED}-network.comcn/cnconfig.php?{random characters}
  • http://updates.{BLOCKED}-network.combinaries/check.php?tcpc=79437
  • http://www.{BLOCKED}etgamebox.com/igb/defaultv2.swf

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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
    • IGB
  • In HKEY_LOCAL_MACHINE\Software
    • IGB
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
    • InternetGameBox
  • In HKEY_CURRENT_USER\Software
    • fcn
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
    • uucbcq

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
    • uucbcq = "%Application Data%\uucbcq.exe uucbcq"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\IGB
    • grpid = "191"
  • In HKEY_CURRENT_USER\Software\IGB
    • grpid = "191"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\IGB
    • InstallOpt1 = "1"
  • In HKEY_CURRENT_USER\Software\IGB
    • InstallOpt1 = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\IGB
    • installdt = "20090109"
  • In HKEY_CURRENT_USER\Software\IGB
    • installdt = "20090109"
  • In HKEY_CURRENT_USER\Software\IGB
    • uai = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\IGB
    • dl_lg = "es"
  • In HKEY_CURRENT_USER\Software\IGB
    • dl_lg = "es"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\InternetGameBox
    • DisplayName = "InternetGameBox "
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\InternetGameBox
    • UninstallString = "%Program Files%\InternetGameBox\uninst.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\InternetGameBox
    • UninstallString2 = "%Program Files%\InternetGameBox\uninst.exe /S"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\InternetGameBox
    • DisplayIcon = "%Program Files%\InternetGameBox\InternetGameBox.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\InternetGameBox
    • URLInfoAbout = "http://www.{BLOCKED}etgamebox.com"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\InternetGameBox
    • Publisher = "OOO «Favorit»"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\IGB
    • Installer Language = "1033"
  • In HKEY_CURRENT_USER\Software\fcn
    • gid = "191"
  • In HKEY_CURRENT_USER\Software\fcn
    • cnid = "lwvtiFTmRl2lmB57PE3kjg"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\uucbcq
    • DisplayName = "Favorit"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\uucbcq
    • UninstallString = "%Application Data%\uucbcq.exe -uninstall"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\uucbcq
    • NoRemove = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\uucbcq
    • NoModify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\uucbcq
    • NoRepair = "1"
  • In HKEY_CURRENT_USER\Software\fcn
    • idt = "201209241539"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\IGB
    • bnrid = "672125"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\SessionInformation
    • From: ProgramCount = "3"
      To: ProgramCount = ""2""
  • In HKEY_CURRENT_USER\SessionInformation
    • From: ProgramCount = "1"
      To: ProgramCount = ""2""
  • In HKEY_CURRENT_USER\SessionInformation
    • From: ProgramCount = "2"
      To: ProgramCount = ""2""

Step 6

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %User Temp%\nsn2.tmp
  • %User Temp%\nsc3.tmp\LangDLL.dll
  • %User Temp%\nsc3.tmp\ioSpecial.ini
  • %User Temp%\nsc3.tmp\modern-wizard.bmp
  • %User Temp%\nsc3.tmp\modern-header.bmp
  • %User Temp%\nsc3.tmp\InstallOptions.dll
  • %Application Data%\uucbcq.exe
  • %Program Files%\InternetGameBox\InternetGameBox.exe
  • %Program Files%\InternetGameBox\ressources\configv2_fr.xml
  • %Program Files%\InternetGameBox\ressources\configv2_en.xml
  • %Program Files%\InternetGameBox\ressources\configv2_es.xml
  • %Program Files%\InternetGameBox\skins\skinv2.skn
  • %Program Files%\InternetGameBox\language
  • %Start Menu%\Programs\InternetGameBox\InternetGameBox.lnk
  • %Start Menu%\Programs\InternetGameBox\Uninstall.lnk
  • %Desktop%\InternetGameBox.lnk
  • %Program Files%\InternetGameBox\uninst.exe
  • %Application Data%\uucbcq.dat
  • %Application Data%\uucbcq_navps.dat
  • %User Temp%\uucbcqpi.tmp
  • %Application Data%\uucbcq_m2s.xml
  • %Application Data%\uucbcq_m2s.zl
  • %Application Data%\uucbcq_s2m.zl
  • %Application Data%\uucbcq_s2m.xml
  • %User Temp%\uucbcqup.tmp
  • %Application Data%\uucbcq_navtmp.dat
  • %Application Data%\uucbcq_navup.dat
  • %User Temp%\uucbcqpic.tmp
  • ressources\favoris\defaultv2.swf
  • %Program Files%\InternetGameBox\ressources\AttenteOn.html
  • %Program Files%\InternetGameBox\ressources\AttenteOff.html

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.
  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\Wilbert
  • %User Profile%\LOCALS~1
  • %User Temp%\nsc3.tmp
  • %Program Files%\InternetGameBox
  • %Program Files%\InternetGameBox\ressources
  • %Program Files%\InternetGameBox\skins
  • %Start Menu%\Programs\InternetGameBox
  • ressources
  • ressources\favoris
  • %Program Files%\InternetGameBox\ressources\favoris

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_SKINTRIM.SM. 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 Temp%\nsn1.tmp
  • %User Temp%\nsc3.tmp


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