Modified by: Rika Joi Gregorio
ALIASES:

W32/Virut.gen.a(McAfee), Virus.Win32.Virut.a (v)(Sunbelt), W32/Virut.AV(Fortinet), Win32/Virut.AV virus(Eset)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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.

It infects files by overwriting code in the entry point and saving the overwritten code in the virus body. It then appends the virus body to the host file. It creates an infection marker in infected files.

It does not have any propagation routine.

It does not have any backdoor routine.

It does not drop any other file.

It does not have any downloading capability.

  TECHNICAL DETAILS

File Size: Varies
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 13 May 2013
Payload: Collects system information, Modifies HOSTS file

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.

Installation

This file infector adds the following mutexes to ensure that only one of its copies runs at any one time:

  • VevT
  • VT_3
  • VT_4
  • Vx_4

Other System Modifications

This file infector creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\winlogon.exe = "%System%\winlogon.exe:*:enabled:@shell32.dll,-1"

File Infection

This file infector infects the following file types:

  • .EXE
  • .SCR

It overwrites code found in the entry point of a target file. It then appends the virus body to the target file. The overwritten code is saved in the virus body.

It creates an infection marker in infected files.

It avoids infecting the following file types:

  • .DLL

It avoids infecting files that contain the following strings in their names:

  • PSTO
  • WC32
  • WCUN
  • WINC

Propagation

This file infector does not have any propagation routine.

Backdoor Routine

This file infector does not have any backdoor routine.

Dropping Routine

This file infector does not drop any other file.

Download Routine

This file infector does not have any downloading capability.

HOSTS File Modification

This file infector adds the following strings to the Windows HOSTS file:

  • 127.0.0.1 NtK{BLOCKED}.info

Information Theft

This file infector gathers the following data:

  • OS Version

NOTES:

This file infector connects to the following IRC server:

  • {BLOCKED}m.{BLOCKED}pa.info

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.300
VSAPI OPR PATTERN File: 5.883.00
VSAPI OPR PATTERN Date: 08 Apr 2009

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

Identify and terminate files detected as PE_VIRUT.AV

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %System%\winlogon.exe = "%System%\winlogon.exe:*:enabled:@shell32.dll,-1"

Step 4

Remove these strings added by the malware/grayware/spyware in the HOSTS file

[ Learn More ]
  • 127.0.0.1 NtK{BLOCKED}.info
"

Step 5

Scan your computer with your Trend Micro product to delete files detected as PE_VIRUT.AV. 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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