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WORM_OTORUN.SHT

October 08, 2012
 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, Copies itself in all available physical drives

This worm arrives via removable drives. 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.

  TECHNICAL DETAILS

File Size:

156,160 bytes

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

10 Mar 2011

Payload:

Connects to URLs/Ips

Arrival Details

This worm arrives via removable drives.

It may arrive via network shares.

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

Installation

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

  • %System%\drivers\services.exe
  • %User Profile%\svchost.exe
  • %User Profile%\Start Menu\Programs\Startup\userinit.exe

(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.. %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
[system] = "%System%\drivers\services.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
winlogon = "%User Profile%\svchost.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
[system] = "%System%\drivers\services.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
winlogon = "%User Profile%\svchost.exe"

It modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%System%\drivers\services.exe"

(Note: The default value data of the said registry entry is "%System%\userinit.exe,".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Schedule
ImagePath = %System%\drivers\services.exe

(Note: The default value data of the said registry entry is %System%\svchost.exe -k netsvcs.)

Propagation

This worm drops the following copies of itself in all physical and removable drives:

  • autorun.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]
ShellExecute=autorun.exe

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}ife.info

NOTES:
This worm searches for shared folders on the affected system and drop a copy of itself onto to the shared folders found.

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI OPR PATTERN File:

7.890.11

VSAPI OPR PATTERN Date:

10 Mar 2011

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 process file/s detected as WORM_OTORUN.SHT

[ Learn More ]

*Note: If the detected file/s is/are not displayed in theWindows Task Manager, continue doing the next steps.

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • [system] = "%System%\drivers\services.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • winlogon = "%User Profile%\svchost.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • [system] = "%System%\drivers\services.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • winlogon = "%User Profile%\svchost.exe"

Step 4

Restore this modified 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
    • From: Userinit = "%System%\userinit.exe,%System%\drivers\services.exe"
      To: "%System%\userinit.exe,"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Schedule
    • From: ImagePath = "%System%\drivers\services.exe  "
      To: "%System%\svchost.exe" -k netsvcs

Step 5

Search and delete AUTORUN.INF files created by WORM_OTORUN.SHT that contain these strings

[ Learn More ]
[autorun]
ShellExecute=autorun.exe

Step 6

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