Analysis by: Abraham Latimer Camba
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm arrives by connecting affected removable drives to a system. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It creates folders in all physical and removable drives. It drops copies of itself in all drives. These dropped copies use the names of the folders located on the said drives for their file names.

  TECHNICAL DETAILS

File Size: 61,440 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 May 2012

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

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

  • %System%\SYSINF0.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.)

Autostart Technique

This worm registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wnetwiss
ImagePath = "%System%\SYSINF0.exe"

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wnetwiss

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wnetwiss\Security

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services
Type = "20"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wnetwiss
Type = "110"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wnetwiss
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wnetwiss
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wnetwiss
DisplayName = "Windows netware work information system setup"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wnetwiss
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wnetwiss
Description = "Provide security by Windows netware work system information "

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wnetwiss\Security
Security = "{hex values}"

It creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
{malware path and filename} = "{malware path and filename}:*:Enabled:SYSINF0"

Propagation

This worm creates the following folders in all physical and removable drives:

  • No Delete .exe

It drops copies of itself in all drives. These dropped copies use the names of the folders located on the said drives for their file names.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.986.02
FIRST VSAPI PATTERN DATE: 10 May 2012
VSAPI OPR PATTERN File: 8.987.00
VSAPI OPR PATTERN Date: 10 May 2012

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

Restart in Safe Mode

[ 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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

 
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Wnetwiss

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\SYSTEM\CurrentControlSet\Services
    • Start = "2"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Type = "20"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • {malware path and filename} = "{malware path and filename}:*:Enabled:SYSINF0"

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_OTORUN.XSF. 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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