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WORM_DORKBOT.AO

November 01, 2013
 Analysis by: Alvin Bacani
 ALIASES:

Worm:Win32/Dorkbot.A (Microsoft); Backdoor.Win32.Ruskill.vbf (Kaspersky)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


This worm arrives via removable drives. It arrives by accessing affected shared networks. 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 deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

190,976 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

31 Oct 2013

Arrival Details

This worm arrives via removable drives.

It arrives by accessing affected shared networks.

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 adds the following folders:

  • {removable drive letter}:\RECYCLER
  • {network drive letter}:\RECYCLER

It drops the following files:

  • {removable drive letter}:\RECYCLER\Desktop.ini
  • {removable drive letter}:\autorun.inf
  • {removable drive letter}:\{folder name}.lnk
  • {network drive letter}:\RECYCLER\Desktop.ini
  • {network drive letter}:\autorun.inf
  • {network drive letter}:\{folder name}.lnk

It drops the following copies of itself into the affected system:

  • %Application Data%\{random file name}.exe

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

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 file name}.exe = "%Application Data%\{random file name}.exe"

Propagation

This worm drops copies of itself in network drives such as the following:

  • {network drive letter}:\RECYCLER\{random filename}.exe

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

  • {removable drive letter}:\RECYCLER\{random filename}.exe

Other Details

This worm connects to the following possibly malicious URL:

  • {BLOCKED}i.{BLOCKED}ia.com
  • {BLOCKED}.{BLOCKED}l.su
  • {BLOCKED}.{BLOCKED}4.su
  • {BLOCKED}.{BLOCKED}u.su
  • {BLOCKED}.{BLOCKED}r.org
  • {BLOCKED}.{BLOCKED}l.su
  • {BLOCKED}.{BLOCKED}4.org
  • {BLOCKED}.{BLOCKED}w.us
  • {BLOCKED}.{BLOCKED}2.su

It deletes the initially executed copy of itself