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: Yes

  • 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 uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

  TECHNICAL DETAILS

File Size: 1,022,120 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 22 Sep 2011

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:

  • %System%\svchoct.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.)

It adds the following possibly malicious files or file components:

  • %User Temp%\E_N4\eAPI.fne
  • %User Temp%\E_N4\eImgConverter.fne
  • %User Temp%\E_N4\krnln.fnr
  • %User Temp%\E_N4\PBShell.fne
  • %User Temp%\E_N4\shell.fne

(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.)

It creates the following folders:

  • %User Temp%\E_N4

(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.)

It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
KXOSUK = "%System%\svchoct.exe"

Propagation

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

  • {space}.exe

NOTES:
This worm searches for folders in all removable drives then drops copies of itself as {folder name}{space}.exe. It then sets the attributes of the found folder to Hidden and System.

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