ALIASES:

Virus:Win32/Virut.E (Microsoft); W32/Virut.gen (McAfee); W32.Virut!gen (Symantec); Virus.Win32.Virut.n (Kaspersky); Win32.Virut.e (v) (Sunbelt); Win32.Virtob.Gen.9 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This file infector 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: 27,648 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 29 Jan 2013

Arrival Details

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

Other System Modifications

This file infector adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Tbsolute

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\NWCWorkstation\Parameters

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Tbsolute
values = "{random values}"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\NWCWorkstation\Parameters
ServiceDll = "%SystemRoot%\system32\nwcwks.dll"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Tbsolute
guid = "B2BB2585-6D4C-4736-9314-510B37CA1A8A"

Dropping Routine

This file infector drops the following files:

  • %System%\nwcwks.dll

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

Other Details

This file infector connects to the following possibly malicious URL:

  • http://www.{BLOCKED}j.com/g1.php?{random characters}

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

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
    • Tbsolute
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\NWCWorkstation
    • Parameters

Step 3

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\Tbsolute
    • values = "{random values}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\NWCWorkstation\Parameters
    • ServiceDll = "%SystemRoot%\system32\nwcwks.dll"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Tbsolute
    • guid = "B2BB2585-6D4C-4736-9314-510B37CA1A8A"

Step 4

Search and delete this file

[ Learn More ]
There may be some 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.
  • %System%\nwcwks.dll

Step 5

Scan your computer with your Trend Micro product to clean files detected as PE_VIRUT.E-1. 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.


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