Modified by: Cris Nowell Pantanilla
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • 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.

  TECHNICAL DETAILS

File Size: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 19 May 2010
Payload: Compromises system security, Connects to URLs/IPs, Infects files

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 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):

  • {BLOCKED}o.brenz.pl
  • {BLOCKED}t.trenz.pl

NOTES:

This file infector hooks certain APIs so that when these APIs are called, the virus code is executed which then infects files. It does not infect files with certain characteristics. It returns execution to the host file's original code after execution.

It may also connect to randomly generated domains for its C&C (command and control) server using a randomizing function, which is computed based on the system's current date and time. The generated domain is {6 random characters}.com.

It connects to the mentioned servers using 8-randomly generated character for its NICK and 1-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.

  SOLUTION

Minimum Scan Engine: 9.200

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

Scan your computer with your Trend Micro product and note files detected as PE_VIRUX.R-3

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

Restart in normal mode and scan your computer with your Trend Micro product for files detected as PE_VIRUX.R-3. 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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