Modified by: Kathleen Notario
ALIASES:

Symantec : W32.Changeup; Microsoft : Virus:Win32/Virut.BI;Mcafee: W32/Virut.n.gen

 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Infects files

This file infector may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

  TECHNICAL DETAILS

File Size: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 12 Nov 2010

Arrival Details

This file infector may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This file infector injects threads into the following normal process(es):

  • WINLOGON.EXE

Other System Modifications

This file infector adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\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 avoids infecting files that contain the following strings in their names:

  • OTSP
  • WC32
  • WCUN
  • WINC

Backdoor Routine

This file infector connects to any of the following IRC server(s):

  • ilo.{BLOCKED}z.pl
  • ant.{BLOCKED}z.pl

HOSTS File Modification

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

  • 127.0.0.1 www.{BLOCKED}z.pl

Other Details

Based on analysis of the codes, it has the following capabilities:

  • It hooks the following APIs so that when these APIs are called, the virus code is executed which then infect files:
    • NtCreateFile
    • NtOpenFile
    • NtCreateProcess
    • NtCreateProcessEx
    • NtQueryInformationProcess
  • It does not infect files with the following characteristics:
    • .DLL files
    • PE Files with _win section name
    • Files with infection marker
  • It also infects script files by first checking if the target script file's extension name is any of the following:
    • .ASP
    • .HTM
    • .PHP
  • Once it finds the targeted script files, it creates a flag for the file for IFRAME infection. It opens the flagged files then checks for a certain string in the file. If it finds that string, it skips the file. If not, it proceeds with the infection of the file. It then looks for the string < /BODY > in the target script file. Once found, it infects script files by inserting the malicious IFRAME code below:
  • It returns execution to the host file's original code after execution.
  • It connects to the mentioned servers using eight randomly-generated character for its NICK and one randomly-generated character for its USER. Once connected to the IRC server, it joins a certain channel to receive and execute commands on the affected system.
  • As of this writing, no reply has been received from the servers.
  • Infected script files are detected as HTML_IFRAME.SMDS.

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 7.620.05
VSAPI PATTERN Date: 14 Nov 2010
VSAPI PATTERN Date: 11/14/2010 12:00:00 AM

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

Remove the malware/grayware file dropped/downloaded by PE_VIRUX.Q. (Note: Please skip this step if the threat(s) listed below have already been removed.)

     HTML_IFRAME.SMDS

Step 3

Restart in Safe Mode

[ Learn More ]

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

Step 5

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

[ Learn More ]
    127.0.0.1 www.{BLOCKED}z.pl

Step 6

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