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TROJ_DNSCHANG.CS
Aliases: Trojan:Win32/Comame (Microsoft); Generic Downloader.x!gc3 (McAfee); Trojan.ADH (Symantec); ARC:NSIS, [panigunhe.dll]:Trojan-Downloader.Win32.Agent.dqec (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.3965030 (FSecure)
Malware type: Trojan
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
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: 168,523 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 07 May 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\ADMINI~1
  • %User Profile%\LOCALS~1
  • %User Temp%\nse3.tmp

(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:\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.. %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.)

Autostart Technique

This Trojan 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\Panigunhe\Parameters

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\nso1.tmp
  • %User Temp%\nse3.tmp
  • %System Root%\DelUS.bat

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

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Panigunhe\Parameters
ServiceDll = "%SystemRoot%\System32\panigunhe.dll"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
netsvcs = "{random characters}"

(Note: The default value data of the said registry entry is {random values}.)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\nso2.tmp
  • %User Temp%\nse3.tmp\System.dll
  • %User Temp%\nse3.tmp\Math.dll
  • %User Temp%\nse3.tmp\MicroCount.dll
  • %System%\panigunhe.dll
  • %User Temp%\nse3.tmp\SetService.dll
  • %User Temp%\nse3.tmp\DLLWebCount.dll
  • %User Temp%\nse3.tmp\SelfDelete.dll
  • \DelUS.bat

(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.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}indow.netweb/counter/install.check.php?{random characters}
  • http://{BLOCKED}soft.net/counter/insert.php?{random characters}

It deletes itself after execution.

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\Panigunhe
    • Parameters

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\ControlSet001\Services\Panigunhe\Parameters
    • ServiceDll = "%SystemRoot%\System32\panigunhe.dll"

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\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • From: netsvcs = "{random characters}"
      To: netsvcs = ""{random values}""

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.
  • %User Temp%\nso2.tmp
  • %User Temp%\nse3.tmp\System.dll
  • %User Temp%\nse3.tmp\Math.dll
  • %User Temp%\nse3.tmp\MicroCount.dll
  • %System%\panigunhe.dll
  • %User Temp%\nse3.tmp\SetService.dll
  • %User Temp%\nse3.tmp\DLLWebCount.dll
  • %User Temp%\nse3.tmp\SelfDelete.dll
  • \DelUS.bat

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\ADMINI~1
  • %User Profile%\LOCALS~1
  • %User Temp%\nse3.tmp

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DNSCHANG.CS. 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%\nso1.tmp
  • %User Temp%\nse3.tmp
  • %System Root%\DelUS.bat


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Analysis By: Automation

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