WORM_AUTORUN.ZYD

This worm arrives via removable drives.

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

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

It deletes itself after execution.

Arrival Details

This worm arrives via removable drives.

Installation

This worm drops the following copies of itself into the affected system:

• %User Temp%\xvassdf.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.)

It injects threads into the following normal process(es):

• Explorer.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
54dfsger = %User Temp%\xvassdf.exe

Other System Modifications

This worm adds the following registry entries as part of its installation routine:

HKEY_CLASSES_ROOT\CLSID\MADOWN
=

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

HKEY_CLASSES_ROOT\CLSID\MADOWN
urlinfo = nedsc.j

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\MADOWN
=

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

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\MADOWN
urlinfo = nedsc.j

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 2

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

(Note: The default value data of the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = 0

(Note: The default value data of the said registry entry is 1.)

Propagation

This worm drops the following copy of itself in all physical and removable drives:

• puia6h.exe

It drops copies of itself in all removable drives.

It drops copies of itself in all physical drives.

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]
open=puia6h.exe
shell\open\Command=puia6h.exe

Other Details

This worm connects to the following possibly malicious URL:

• http://www.yahoosd3.com/1rb/ar1.rar
• http://www.googlecvn.com/1rb/ar.rar

It deletes itself after execution.