WORM_FLYSTUDI.B

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats.

Arrival Details

This worm 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:

• %User Temp%\E_4\dp1.fne
• %User Temp%\E_4\eAPI.fne
• %User Temp%\E_4\EThread.fne
• %User Temp%\E_4\internet.fne
• %User Temp%\E_4\krnln.fnr
• %User Temp%\E_4\sock.fne

(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.)

It creates the following folders:

• %User Temp%\E_4

(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.)

Autostart Technique

This worm registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Audio Server
Type = 10

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Audio Server
Start = 2

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Audio Server
ErrorControl = 1

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Audio Server
ImagePath = "{malware path and file name}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Audio Server
DisplayName = "Windows Audio Server"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Audio Server
ObjectName = "LocalSystem"

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Audio Server

Download Routine

This worm connects to the following malicious URLs:

• {BLOCKED}2.{BLOCKED}8.1.51:1021