TROJ_SMALL.NQN


 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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

33,792 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

13 Dec 2013

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 drops the following copies of itself into the affected system:

  • %Temp%\~tmp81.tmp
  • %Temp%\~tmp85.tmp

(Note: %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)

It creates the following folders:

  • taskmgr.exe.manifest
  • tasklist.exe.manifest

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A37AE135-9BD0-3468-ACD0-3467ACE02457}
StubPath = "%Program Files%\Internet Explorer\iecheck.com"

Other System Modifications

This Trojan deletes the following files:

  • %System Root%\$$$$$$$$.cmd

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Active Setup\Installed Components\{A37AE135-9BD0-3468-ACD0-3467ACE02457}

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfEscapement = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfOrientation = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfWeight = "19"

(Note: The default value data of the said registry entry is 190.)

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfItalic = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfUnderline = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfStrikeOut = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfCharSet = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfOutPrecision = "1"

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfClipPrecision = "2"

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

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfQuality = "2"

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

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfPitchAndFamily = "31"

(Note: The default value data of the said registry entry is 31.)

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iPointSize = "64"

(Note: The default value data of the said registry entry is 64.)

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
fWrap = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
StatusBar = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
fSaveWindowPositions = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
lfFaceName = "Lucida Console"

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

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
szHeader = "&f"

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

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
szTrailer = "Page &p"

(Note: The default value data of the said registry entry is Page &p.)

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iMarginTop = "3e8"

(Note: The default value data of the said registry entry is 3e8.)

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iMarginBottom = "3e8"

(Note: The default value data of the said registry entry is 3e8.)

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iMarginLeft = "2ee"

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

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iMarginRight = "2ee"

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

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
fMLE_is_broken = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iWindowPosX = "16"

(Note: The default value data of the said registry entry is 42.)

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iWindowPosY = "1d"

(Note: The default value data of the said registry entry is 57.)

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iWindowPosDX = "3"

(Note: The default value data of the said registry entry is 258.)

HKEY_CURRENT_USER\Software\Microsoft\
Notepad
iWindowPosDY = "212"

(Note: The default value data of the said registry entry is 194.)

HKEY_CURRENT_USER\SessionInformation
ProgramCount = "1"

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

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A37AE135-9BD0-3468-ACD0-3467ACE02457}\
Software\Microsoft\Active Setup\
Installed Components\{A37AE135-9BD0-3468-ACD0-3467ACE02457}

HKEY_CURRENT_USER\Software\Microsoft\
Active Setup\Installed Components\{A37AE135-9BD0-3468-ACD0-3467ACE02457}

Dropping Routine

This Trojan drops the following files:

  • %System Root%\note.reg
  • %System Root%\$$$$$$$$.txt
  • %Program Files%\Internet Explorer\iecheck.com
  • %Windows%\notepad2.exe

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}114.com:56/xueluo.txt
  • http://{BLOCKED}114.com6admin_sajajdidj/Count.asp?{random characters}

It deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components
    • {A37AE135-9BD0-3468-ACD0-3467ACE02457}

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\SOFTWARE\Microsoft\Active Setup\Installed Components\{A37AE135-9BD0-3468-ACD0-3467ACE02457}
    • StubPath = "%Program Files%\Internet Explorer\iecheck.com"

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\Software\Microsoft\Notepad
    • lfEscapement = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • lfOrientation = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: lfWeight = "19"
      To: lfWeight = ""190""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • lfItalic = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • lfUnderline = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • lfStrikeOut = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • lfCharSet = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: lfOutPrecision = "1"
      To: lfOutPrecision = ""1""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: lfClipPrecision = "2"
      To: lfClipPrecision = ""2""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: lfQuality = "2"
      To: lfQuality = ""2""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: lfPitchAndFamily = "31"
      To: lfPitchAndFamily = ""31""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: iPointSize = "64"
      To: iPointSize = ""64""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • fWrap = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • StatusBar = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • fSaveWindowPositions = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: lfFaceName = "Lucida Console"
      To: lfFaceName = ""Lucida Console""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: szHeader = "&f"
      To: szHeader = ""&f""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: szTrailer = "Page &p"
      To: szTrailer = ""Page &p""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: iMarginTop = "3e8"
      To: iMarginTop = ""3e8""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: iMarginBottom = "3e8"
      To: iMarginBottom = ""3e8""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: iMarginLeft = "2ee"
      To: iMarginLeft = ""2ee""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: iMarginRight = "2ee"
      To: iMarginRight = ""2ee""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • fMLE_is_broken = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: iWindowPosX = "16"
      To: iWindowPosX = ""42""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: iWindowPosY = "1d"
      To: iWindowPosY = ""57""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: iWindowPosDX = "3"
      To: iWindowPosDX = ""258""
  • In HKEY_CURRENT_USER\Software\Microsoft\Notepad
    • From: iWindowPosDY = "212"
      To: iWindowPosDY = ""194""
  • In HKEY_CURRENT_USER\SessionInformation
    • From: ProgramCount = "1"
      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.
  • %System Root%\note.reg
  • %System Root%\.txt
  • %Program Files%\Internet Explorer\iecheck.com
  • %Windows%\notepad2.exe
.txt
  • %Program Files%\Internet Explorer\iecheck.com
  • %Windows%\notepad2.exe
  • In the Look In drop-down list, select My Computer then press Enter.
  • Once located, select the file then press SHIFT+DELETE to delete it.
  • Repeat the said steps for all files listed.
  • • For Windows Vista and Windows 7 users:

    1. Click Start>Computer.
    2. In the Search input box, type:
      • %System Root%\note.reg
      • %System Root%\.txt
      • %Program Files%\Internet Explorer\iecheck.com
      • %Windows%\notepad2.exe
    3. Once located, select the file then press SHIFT+DELETE to delete it.
    4. Repeat the said steps for all files listed.
      *Note: Read the following Microsoft page if these steps do not work on Windows 7.

    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.
    • taskmgr.exe.manifest
    • tasklist.exe.manifest

    Step 8

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

    • %System Root%\.cmd

    Step 10

    Restore these deleted registry keys/values from backup

    *Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\Software\Microsoft\Active Setup\Installed Components
      • {A37AE135-9BD0-3468-ACD0-3467ACE02457}
    • In HKEY_CURRENT_USER\Software\Microsoft\Active Setup\Installed Components
      • {A37AE135-9BD0-3468-ACD0-3467ACE02457}


    Did this description help? Tell us how we did.