Analysis by: Adrian Cofreros
ALIASES:

Worm:Win32/Dorkbot.AQ(Microsoft),Trojan-Ransom.Win32.Blocker.ayst(Kaspersky),Trojan.Win32.Generic!BT(Sunbelt)

 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:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • 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 itself after execution.

  TECHNICAL DETAILS

File Size: 282,112 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 06 Jun 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:

  • %Application Data%\help
  • {removable drive letter}:\snkb0pt
  • {network drive letter}:\snkb0pt

(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.)

It drops the following files:

  • {removable drive letter}:\snkb0pt\Desktop.ini
  • {removable drive letter}:\autorun.inf
  • {removable drive letter}:\{folder name}.lnk
  • {network drive letter}:\snkb0pt\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}:\snkb0pt\snkb0pt.exe

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

  • {removable drive letter}:\snkb0pt\snkb0pt.exe

Other Details

This worm connects to the following possibly malicious URL:

  • {BLOCKED}d-by.{BLOCKED}fastserver.com

It deletes itself after execution.