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VBS_AUTORUN.SMJ

October 08, 2012
 Analysis by: JasperM
 PLATFORM:

Windows 2000, XP, Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Trojan arrives by connecting affected removable drives to a system. It may be dropped by other malware. 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.

However, due to errors in its code, it fails to perform its intended routine.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

Script

Memory Resident:

No

Initial Samples Received Date:

17 Jun 2010

Arrival Details

This Trojan arrives by connecting affected removable drives to a system.

It may be dropped by other malware.

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

Installation

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

  • %System%\winjpg.jpg

(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.)

It adds the following processes:

  • WSCRIPT.EXE

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
CTFMON = %System%\wscript.exe /E:vbs %System%\winjpg.jpg

Propagation

This Trojan drops the following copy(ies) of itself in all removable drives:

  • winfile.jpg

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 /e: vbs winfile.jpg

Other Details

However, due to errors in its code, it fails to perform its intended routine.

  SOLUTION

Minimum Scan Engine:

8.9

VSAPI PATTERN File:

7.253.80

VSAPI PATTERN Date:

18 Jun 2010

VSAPI PATTERN Date:

6/18/2010 12:00:00 AM

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

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\Windows\CurrentVersion\Run
    • CTFMON=%System%\wscript.exe /E:vbs%System%\winjpg.jpg

Step 4

Scan your computer with your Trend Micro product to delete files detected as VBS_AUTORUN.SMJ. 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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