WORM_NUQEL.AX

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 uses Windows Task Scheduler to create a scheduled task that executes the dropped copy. It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

It disables Task Manager, Registry Editor, and Folder Options. It deletes autostart registry entries associated with the processes it terminates to completely disable applications.

It propagates via shared networks and drops copies of itself into available networks.

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

As of this writing, the said sites are inaccessible.

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 a copy of itself in the following folders using different file names:

• %Windows%\IEXPLORER.EXE
• %System%\IEXPLORER.EXE
• %System%\WORD.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It drops the following component file(s):

• %Windows%\setting.ini
• %System%\autorun.ini
• %Windows%\Tasks\At1.job

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

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
Yahoo Messengger = "%System%\IEXPLORER.exe"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe IEXPLORER.exe"

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

The scheduled task executes the malware at the following period:

• Everyday at 09:00

Other System Modifications

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
GlobalUserOffline = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Schedule
AtTaskMaxHours = "0"

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NofolderOptions = "1"

It deletes autostart registry entries associated with the processes it terminates to completely disable applications.

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Minimal\
{4D36E967-E325-11CE-BFC1-08002BE10318}
{default} = "DiskDrive"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Network\
{4D36E967-E325-11CE-BFC1-08002BE10318}
{default} = "DiskDrive"

File Infection

This worm propagates via shared networks and drops copies of itself into available networks.

Propagation

This worm drops copies of itself in the following shared folders:

• game_y.exe

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

• Bi mat.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:

[Autorun]
Open=IEXPLORER.exe
Shellexe cute=IEXPLORER.exe
Shell\Open\command=IEXPLORER.exe
Shell=Open

Backdoor Routine

This worm connects to the following URL(s) to send and receive commands from a remote malicious user:

• {BLOCKED}.{BLOCKED}.128.132:80

Download Routine

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

• http://setting.{BLOCKED}b.com/setting.doc
• http://hvaonline.com.{BLOCKED}pages.com/setting.doc
• http://setting3.{BLOCKED}5.com/setting.doc

As of this writing, the said sites are inaccessible.

Other Details

This worm does the following:

• Disable Security feature by deleting Registry keys
• Disable Rebooting through Safe Mode
• Downloads and Executes other malicious files