TROJ_WIMPIXO.AP


 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:

116,224 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 Nov 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.

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\Ias\Parameters

Other System Modifications

This Trojan deletes the following files:

  • %System%\6to4v32.dll
  • %System%\Iasex.dll

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\netcard
Description = "netcard"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ias
Type = "4"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ias
Description = "HTTP Security Services Helper"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ias\Parameters
ServiceDll = "%System%\Iasex.dll"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Ias
InstallModule = "%System%\wuauclt.exe"

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}.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\6to4
Description = "Windows Network Security Management Service"

(Note: The default value data of the said registry entry is Provides DDNS name registration and automatic IPv6 connectivity over an IPv4 network. If this service is stopped, other computers may not be able to reach it by name and the machine will only have IPv6 connectivity if it is connected to a native IPv6 network. If this service is disabled, any other services that explicitly depend on this service will fail to start..)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\6to4
DisplayName = "Network Security"

(Note: The default value data of the said registry entry is IPv6 Helper Service.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\6to4
Type = "12"

(Note: The default value data of the said registry entry is 20.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\6to4\Parameters
ServiceDll = "%System%\6to4v32.dll"

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

Dropping Routine

This Trojan drops the following files:

  • %Temp%\clk401.nls
  • %Temp%\clk263.nls
  • %User Temp%\1383854029_res.tmp

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

Other Details

This Trojan 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\SYSTEM\CurrentControlSet\Services\Ias
    • 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\netcard
    • Description = "netcard"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Ias
    • Type = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Ias
    • Description = "HTTP Security Services Helper"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Ias\Parameters
    • ServiceDll = "%System%\Iasex.dll"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Ias
    • InstallModule = "%System%\wuauclt.exe"

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • From: netsvcs = "{random characters}"
      To: netsvcs = ""{random values}""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\6to4
    • From: Description = "Windows Network Security Management Service"
      To: Description = ""Provides DDNS name registration and automatic IPv6 connectivity over an IPv4 network. If this service is stopped, other computers may not be able to reach it by name and the machine will only have IPv6 connectivity if it is connected to a native IPv6 network. If this service is disabled, any other services that explicitly depend on this service will fail to start.""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\6to4
    • From: DisplayName = "Network Security"
      To: DisplayName = ""IPv6 Helper Service""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\6to4
    • From: Type = "12"
      To: Type = ""20""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\6to4\Parameters
    • From: ServiceDll = "%System%\6to4v32.dll"
      To: ServiceDll = ""{random values}""

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.
  • %Temp%\clk401.nls
  • %Temp%\clk263.nls
  • %User Temp%\1383854029_res.tmp

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_WIMPIXO.AP. 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 8

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%\6to4v32.dll
  • %System%\Iasex.dll


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