Analysis by: Cris Nowell Pantanilla
 PLATFORM:

Windows 2000, 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 drops copies of itself in all removable and physical drives found in the system. 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: 398,527 bytes
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 02 Sep 2010

Installation

This worm adds the following folders:

  • %Windows%\BackUp

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

It drops the following copies of itself into the affected system:

  • %Drive%\explorer.exe
  • %Windows%\BackUp\explorer.exe
  • %Program Files%\explorer.exe
  • %Program Files%\{17350501621331}.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

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
explorer = %WINDOWS%\BackUp\explorer.exe

Other System Modifications

This worm adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
{17350501621331} = %Drive%\explorer.exe

Propagation

This worm drops copies of itself in all removable and physical drives found in the system.

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=explorer.exe
shellexecute=explorer.exe
shell\Explore\command=explorer.exe
shell\Open\command=explorer.exe
shell=Explore

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI OPR PATTERN File: 7.428.13
VSAPI OPR PATTERN Date: 02 Sep 2010

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

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.  %Windows%\BackUp

Step 3

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

[ Learn More ]
[autorun]
open=explorer.exe
shellexecute=explorer.exe
shell\Explore\command=explorer.exe
shell\Open\command=explorer.exe
shell=Explore

Step 4

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