Analysis by: Michael Cabel
 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

Infection Channel: Propagates via removable drives

This worm drops copies of itself in all 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: 167,938 bytes
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 24 Aug 2010

Installation

This worm is injected into the following processes running in memory:

  • EXPLORER.EXE

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Taskman = {malware path and file name}.EXE

Propagation

This worm creates the following folders in all removable drives:

  • USBSYSTEM

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

  • usp.exe

It drops copies of itself in all 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.

The said .INF file contains the following strings:

[autorun]
open=USBSYSTEM/usp.exe
{Garbage Characters}
icon=%SystemRoot%\system32\SHELL32.dll,4
{Garbage Characters}
action=Open folder to view files using Windows Explorer
{Garbage Characters}
shell\\open\\command=USBSYSTEM/usp.exe
{Garbage Characters}
shell\\explore\\command=USBSYSTEM/usp.exe
{Garbage Characters}
useautoplay=1
{Garbage Characters}

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI OPR PATTERN File: 7.429.00
VSAPI OPR PATTERN Date: 25 Aug 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

Scan your computer with your Trend Micro product and note files detected as WORM_AUTORUN.FOV

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\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Taskman = {malware path and file name}.EXE

Step 5

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