WORM_DORKBOT.MA

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 executes then deletes itself afterward.

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

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 files:

• {removable drive letter}:\snkb0pt\Desktop.ini

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

• %Application Data%\{random letters}.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.)

It executes then deletes itself afterward.

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 letters}.exe = "%Application Data%\{random letters}.exe"

Propagation

This worm creates the following folders in all removable drives:

• {removable drive letter}:\snkb0pt

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

• {removable drive letter}:\snkb0pt\snkb0pt.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}
{removable drive letter}:\snkb0pt\snkb0pt.exe
;{garbage characters}

Download Routine

This worm connects to the following URL(s) to download its component file(s):

• http://{BLOCKED}le.com/dl/205452604/6f84474/.mc983yh31.html
• http://s431.{BLOCKED}le.com/get/2888d27a1ee5f38b144b9b501c432d26367f4e1e/517e54d7/2/d8e48ceedf39c8b9/c3ef53c/.mc983yh3%5B1

It saves the files it downloads using the following names:

• %User Temp%\{random letters}.exe

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Other Details

This worm connects to the following possibly malicious URL:

• http://{BLOCKED}n.de
• http://f.{BLOCKED}on.pl
• http://s.{BLOCKED}b.pl
• http://xray868.{BLOCKED}4you.de
• http://{BLOCKED}.7.199
• http://{BLOCKED}.120.74
• http://xxxxxxxxxxxxxxx.{BLOCKED}i.su
• http://{BLOCKED}.165.213

NOTES:
It drops shortcut files pointing to the copy of itself in removable drives.

These dropped .LNK files use the names of the folders located on the said drives for their file names.

It then sets the attributes of the original folders to Hidden to trick the user into clicking the .LNK files.