PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Others

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Propagates via removable drives, Copies itself in all available physical drives

This malware may arrive bundled with malware packages as a malware component. It may be unknowingly downloaded by a user while visiting malicious websites.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size: 7,486 bytes
File Type: Script
Memory Resident: Yes
Initial Samples Received Date: 14 Mar 2007
Payload: Drops files

Arrival Details

This malware may arrive bundled with malware packages as a malware component.

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

Installation

This malware drops the following copies of itself into the affected system:

  • %System%\killVBS.vbs

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Autostart Technique

This malware modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%System%\wscript.exe "%system%\killVBS.vbs""

(Note: The default value data of the said registry entry is %System%\userinit.exe,.)

Propagation

This malware drops copies of itself in the following drives:

  • C: to Z:

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[Autorun]
shellexecute=wscript.exe killVBS.vbs

NOTES:

This malicious VBScript requires the presence of the normal file WSCRIPT.EXE to execute properly.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 5.132.21
FIRST VSAPI PATTERN DATE: 01 Mar 2008

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Terminate a malware/grayware process

[ Learn More ]

*Note: If the detected process is not displayed in theWindows Task Manager, continue doing the next steps.

    WSCRIPT.EXE

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Restore this modified 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\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "System%userinit.exe,%System%\wscript.exe "%system%killVBS.vbs""
      To: Userinit = "%System%\userinit.exe,"

Step 5

Search and delete AUTORUN.INF files created by VBS_PICA.AE that contain these strings

[ Learn More ]

[AutoRun]

shellexecute=wscript.exe killVBS.vbs

Step 6

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