TROJ_CUTWAIL.YAC

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

It deletes itself after execution.

Arrival Details

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

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random filename.exe} = "%System%\{random file name}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random filename.exe} = "%User Profile%\{random file name}.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\WinNTData

HKEY_CURRENT_USER\Software\WinNTData

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\WinNTData
prx = "{hex values}"

HKEY_CURRENT_USER\Software\WinNTData
prx = "{hex values}"

Dropping Routine

This Trojan drops the following files:

• %System%\{random file name}.exe
• %User Profile%\{random file name}.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Other Details

This Trojan deletes itself after execution.