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WORM_AUTORUN.SMT

May 06, 2013
 Analysis by: Sabrina Lei Sioting
 PLATFORM:

Windows 2000, Windows XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This worm arrives via removable drives.

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:

72,704 bytes

Memory Resident:

Yes

Initial Samples Received Date:

02 Mar 2010

Arrival Details

This worm arrives via removable drives.

Installation

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

  • %Windows%\Wnet.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

It drops the following component file(s):

  • %Windows%\ud.sys

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
MSN = "%Windows%\Wnet.exe"

Propagation

This worm creates the following folders in all removable drives:

  • RECYCLER
  • RECYCLER\S-1-6-21-2434476501-1644491937-600003330-1213

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

  • RECYCLER\S-1-6-21-2434476501-1644491937-600003330-1213\flasher.exe

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]
open=RECYCLER\S-1-6-21-2434476501-1644491937-600003330-1213\flasher.exe
icon=%SystemRoot%\system32\SHELL32.dll,4
action=Open folder to view files
shell\open=Open
shell\open\command=RECYCLER\S-1-6-21-2434476501-1644491937-600003330-1213\flasher.exe
shell\open\default=1

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

6.886.05

FIRST VSAPI PATTERN DATE:

02 Mar 2010

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

Terminate a malware/grayware process

[ Learn More ]

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

     %Windows%\Wnet.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
    • MSN = %Windows%\Wnet.exe

Step 4

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • {drive letter}\RECYCLER

Step 5

Search and delete AUTORUN.INF files created by WORM_AUTORUN.SMT that contain these strings

[ Learn More ]


[AutoRun]
open=RECYCLER\S-1-6-21-2434476501-1644491937-600003330-1213\flasher.exe
icon=ϿstemRootϿystem32\SHELL32.dll,4
action=Open folder to view files
shell\open=Open
shell\open\command=RECYCLER\S-1-6-21-2434476501-1644491937-600003330-1213\flasher.exe
shell\open\default=1

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.SMT. 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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