Analysis by: Cris Nowell Pantanilla

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This worm arrives via removable drives.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 65,544 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 07 Apr 2010

Arrival Details

This worm arrives via removable drives.

It may arrive via network shares.

Installation

This worm drops the following non-malicious files:

  • %User Temp%\srv{random}.ini

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

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

  • %User Temp%\srv{random}.tmp
  • {Shared Folder}\setup50045.fon

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It injects threads into the following normal process(es):

  • spoolsv.exe

Autostart Technique

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\srv{random}\parameters
servicedll = "%User Temp%\srv{random}.tmp"

It adds the following entries to allow itself to run on safe mode:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Minimal\
srv{random}
(Default) = "service"

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}.{BLOCKED}.48.173
  • http://{BLOCKED}.{BLOCKED}.193.21
  • http://{BLOCKED}.{BLOCKED}.88.10/

However, as of this writing, the said sites are inaccessible.

NOTES:

It drops the following files in shared folders:

  • {Shared Folder}\autorun.inf
  • {Shared Folder}\myporno.avi.lnk
  • {Shared Folder}\pornmovs.lnk
  • {Shared Folder}\setup50045.lnk

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.198.05
FIRST VSAPI PATTERN DATE: 02 Jun 2011

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

Identify and delete files detected as WORM_OTORUN.SM6 using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

Delete this registry key

[ 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\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal
    • srv{random}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • srv{random}

Step 4

Search and delete these components

[ Learn More ]
There may be some components that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • {Shared Folder}\autorun.inf
  • {Shared Folder}\myporno.avi.lnk
  • {Shared Folder}\pornmovs.lnk
  • {Shared Folder}\setup50045.lnk
  • %User Temp%\srv{random}.ini

Step 5

Scan your computer with your Trend Micro product to delete files detected as WORM_OTORUN.SM6. 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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