TROJ_FAKEAV.CRZ

This Trojan employs registry shell spawning by adding certain registry entries. This allows this malware to execute even when other applications are opened.

It bypasses the Windows firewall. This allows the malware to perform its intended routine without being detected by an installed firewall.

It deletes itself after execution.

It displays fake alerts that warn users of infection. It also displays fake scanning results of the affected system. It then asks for users to purchase it once scanning is completed. If users decide to purchase the rogue product, users are directed to a certain website asking for sensitive information, such as credit card numbers.

Installation

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

• %User Profile%\Local Settings\Application Data\{random three letters}.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It drops the following files:

• %system root%\Documents and Settings\All Users\Application Data\tmf5lj7dlu1u0wa5rigs0i5qno01yg5g35b8t78yk25h4h
• %User Profile%\Local Settings\Application Data\tmf5lj7dlu1u0wa5rigs0i5qno01yg5g35b8t78yk25h4h
• %User Temp%\tmf5lj7dlu1u0wa5rigs0i5qno01yg5g35b8t78yk25h4h
• %User Profile%\Templates\tmf5lj7dlu1u0wa5rigs0i5qno01yg5g35b8t78yk25h4h

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %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.)

Autostart Technique

This Trojan employs registry shell spawning to ensure its execution when certain file types are accessed by adding the following entries:

HKEY_CLASSES_ROOT\.exe\shell\
open\command
@ = "%User Profile%\Local Settings\Application Data\{random three letters}.exe" -a "%1" %*

HKEY_CURRENT_USER\Software\Classes\
.exe\shell\open\
command
@ = "%User Profile%\Local Settings\Application Data\{random three letters}.exe" -a "%1" %*

HKEY_CURRENT_USER\Software\Classes\
exefile\shell\open\
command
@ = "%User Profile%\Local Settings\Application Data\{random three letters}.exe" -a "%1" %*

Other System Modifications

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusDisableNotify = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusOverride = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallDisableNotify = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallOverride = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UpdatesDisableNotify = 1

It modifies the following registry key(s)/entry(ies) as part of its installation routine:

HKEY_CLASSES_ROOT\exefile\shell\
open\command
@ = "%User Profile%\Local Settings\Application Data\{random three letters}.exe" -a "%1" %*

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

It modifies the following registry entries to disable the Windows Firewall settings:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
EnableFirewall = 0

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
DisableNotifications = 1

(Note: The default value data of the said registry entry is 0.)

It creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile
EnableFirewall = 0

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile
DoNotAllowExceptions = 0

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile
DisableNotifications = 1

Other Details

This Trojan deletes itself after execution.

Rogue Antivirus Routine

This Trojan displays fake alerts that warn users of infection. It also displays fake scanning results of the affected system. It then asks for users to purchase it once scanning is completed. If users decide to purchase the rogue product, users are directed to a certain website asking for sensitive information, such as credit card numbers.