WORM_DORKBOT.SMM

This worm arrives by connecting affected removable drives to a system. 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 drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It executes commands from a remote malicious user, effectively compromising the affected system.

It deletes the initially executed copy of itself.

Arrival Details

This worm arrives by connecting affected removable drives to a system.

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 drops the following component file(s):

• {removable drive letter}:\snkb0ptz\Desktop.ini
• {removable drive letter}:\{folder name}.lnk
• {network drive letter}:\snkb0ptz\Desktop.ini
• {network drive letter}:\{folder name}.lnk

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

• %Application Data%\{random}.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 creates the following folders:

• {removable drive letter}:\snkb0ptz
• {network drive letter}:\snkb0ptz

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• snkb0ptz

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

Propagation

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

• {network drive letter}:\snkb0ptz\snkb0ptz.exe

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

• {removable drive letter}:\snkb0ptz\snkb0ptz.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 or network drive letter}:\snkb0ptz\snkb0ptz.exe
;{garbage characters}
{removable or network drive letter}:\snkb0ptz\snkb0ptz.exe
;{garbage characters}
{removable or network drive letter}:\snkb0ptz\snkb0ptz.exe
;{garbage characters}

Backdoor Routine

This worm connects to any of the following IRC server(s):

• {BLOCKED}.{BLOCKED}.71.238:9000
• {BLOCKED}.{BLOCKED}.173.154:9000
• {BLOCKED}.{BLOCKED}.86.198:9000

It executes the following commands from a remote malicious user:

• Update itself
• Join/Leave an IRC channel
• Download other files
• Perform Slowloris, UDP, and SYN flooding
• Create processes

Download Routine

This worm connects to the following website(s) to download and execute a malicious file:

• http://{BLOCKED}e.com/dl/208146938/aab93b5/000660.html
• http://{BLOCKED}e.com/dl/208146938/aab93b5/000660.html
• http://{BLOCKED}e.com/dl/208146938/aab93b5/000660.html
• http://{BLOCKED}e.com/dl/208146938/aab93b5/000660.html
• http://{BLOCKED}3.{BLOCKED}e.com/get/2ad2d3a9d0b6f89fdf3a02cb988b7431e2e6a7dd/5180aa32/2/183ad0654f954a7a/c6811fa/000660
• http://{BLOCKED}3.{BLOCKED}e.com/get/8ee83e2f2630eaf9a8ac9fd89d25367560101d66/5180a930/2/183ad0654f954a7a/c6811fa/000660
• http://{BLOCKED}3.{BLOCKED}e.com/get/b7ccfa350b21feac3c194f7047a6e0de57a9cbe8/5180a9bd/2/183ad0654f954a7a/c6811fa/000660
• http://{BLOCKED}3.{BLOCKED}e.com/get/f597281a91151992855fa801ab3e60c8875bb936/5180ab92/2/183ad0654f954a7a/c6811fa/000660
• http://{BLOCKED}3.{BLOCKED}e.com/get/f597281a91151992855fa801ab3e60c8875bb936/5180ab92/2/183ad0654f954a7a/c6811fa/000660

It saves the files it downloads using the following names:

• %User Temp%\{random}.exe - detected as WORM_DORKBOT.SME

(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 deletes the initially executed copy of itself

NOTES:
It drops shortcut files pointing to its copy in removable and network 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.