Analysis by: Sabrina Lei Sioting
 PLATFORM:

Windows 2000, Windows XP, Windows 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 arrives by connecting affected removable drives to a system.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 758,272 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 05 Mar 2009

Arrival Details

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

Installation

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

  • %System Root%\autorun.pif
  • %Windows%\svchost.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_TRKNETSSVCS\
0000
Service = "TrkNetsSvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_TRKNETSSVCS\
0000
DeviceDesc = "Distributed Link Tracking Servers"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_TRKNETSSVCS\
0000\Control
ActiveService = "TrkNetsSvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TrkNetsSvcs
ImagePath = "%Windows%\svchost.exe -netsvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TrkNetsSvcs
DisplayName = "Distributed Link Tracking Servers"

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_TRKNETSSVCS

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TrkNetsSvcs

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_TRKNETSSVCS\
0000

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%WINDOWS%\svchost.exe = "%WINDOWS%\svchost.exe:*:Enabled:svchost.exe"

Propagation

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

  • autorun.pif

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=autorun.pif
shell\1=´ò¿ª(&O)
shell\1\Command=autorun.pif
shell\2\=ä¯ÀÀ(&B)
shell\2\Command=autorun.pif
shellexecute=autorun.pif

Other Details

This worm deletes the initially executed copy of itself