WORM_VOBFUS.TT

January 04, 2013
 Modified by: Rika Joi Gregorio
 ALIASES:

Worm:Win32/Vobfus (Microsoft), Worm.Win32.Vobfus.amyv (Kaspersky), Win32/Pronny.JB worm (Eset)

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

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

It modifies certain registry entries to hide Hidden files.

  TECHNICAL DETAILS

File Size:

364,544 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

12 Dec 2012

Arrival Details

This worm 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:

  • %User Profile%\{random}.exe
  • %User Profile%\Passwords.exe
  • %User Profile%\Porn.exe
  • %User Profile%\Secret.exe
  • %User Profile%\Sexy.exe

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

It drops the following files:

  • %User Profile%\msn.com
  • {drive letter}\x.mpeg

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
{random} = "%User Profile%\{random}.exe /{random letter}"

Other System Modifications

This worm adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\WindowsUpdate\
AU
NoAutoUpdate = "1"

Propagation

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

  • {drive letter}\Passwords.exe
  • {drive letter}\Porn.exe
  • {drive letter}\Secret.exe
  • {drive letter}\{random}.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:

{garbage characters}
[autorun]
{garbage characters}
open={random}.eXe
{garbage characters}
action={random numbers}
{garbage characters}
useaUTOPLAY=1
{garbage characters}

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}7.{BLOCKED}p.at:443/ObFoyyb?f
  • {BLOCKED}1.{BLOCKED}ecks.com

It modifies the following registry entries to hide Hidden files:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

(Note: The default value data of the said registry entry is 1.)