TROJ_CUTWAIL.YYN

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 the initially executed copy of itself.

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.

Installation

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

• %User Profile%\qcvwyryn.exe
• %System%\qcvwyryn.exe

(Note: %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.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

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

HKEY_CURRENT_USER\SOFTWARE\Microsft\
Windows\CurrentVersion\Run
qcvwyryn = "%User Profile%\qcvwyryn.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsft\
Windows\CurrentVersion\Run
qcvwyryn = "%System%\qcvwyryn.exe"

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\WindNTData
prx = "{data}"

Other Details

This Trojan deletes the initially executed copy of itself