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WORM_VOBFUS.GD

November 22, 2012
 Analysis by: Rika Joi Gregorio
 ALIASES:

Worm:Win32/Vobfus.GD (Microsoft), Win32/AutoRun.VB.AXS worm (Eset), Trojan.Win32.Vobfus.paa (v) (Sunbelt)

 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 modifies registry entries to hide files with System and Read-only attributes.

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:

86,016 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 Nov 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:

  • %UserProfile%\{random}.exe

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 /x"

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\WindowsUpdate\
AU
NoAutoUpdate = "00000001"

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\WindowsUpdate\
AU

It modifies the following registry entries to hide files with System and Read-only attributes:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSupperHidden = "00000001"

(Note: The default value data of the said registry entry is 00000000.)

Propagation

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

  • {Drive Letter}\Porn.exe
  • {Drive Letter}\Secret.exe
  • {Drive Letter}\Sexy.exe
  • {Drive Letter}\{random}.exe
  • {Drive Letter}\Passwords.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]
Icon={random}.exe,0
open={RANDOM}.eXE
ActION=2026
USeauToplaY=1

Other Details

This worm connects to the following possibly malicious URL:

  • ns1.{BLOCKED}eckings.com
  • ns1.{BLOCKED}eckings.net
  • ns1.{BLOCKED}nes.org