TROJ_FAKEAV.DRW

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 adds registry entries to enable its automatic execution at every system startup.

It adds certain registry entries to disable the Task Manager. This action prevents users from terminating the malware process, which can usually be done via the Task Manager.

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:

• %System Root%\Documents and Settings\All Users\Application Data\{random}.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It drops the following files:

• %Application Data%\Microsoft\Internet Explorer\Quick Launch\System Restore.lnk
• %Desktop%\System Restore.lnk
• %Start Menu%\Programs\System Restore\System Restore.lnk
• %Start Menu%\Programs\System Restore\Uninstall System Restore.lnk
• %System Root%\Documents and Settings\All Users\Application Data\{random}
• %System Root%\Documents and Settings\All Users\Application Data\{random}.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.. %Desktop% is the current user's desktop, which is usually C:\Windows\Profiles\{user name}\Desktop on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Desktop on Windows NT, and C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003.. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Profiles\{user name}\Start Menu on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu on Windows NT and C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It creates the following folders:

• %User Temp%\smtmp
• %User Temp%\smtmp\1
• %User Temp%\smtmp\2
• %User Temp%\smtmp\3
• %User Temp%\smtmp\4
• %Start Menu%\Programs\System Restore

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

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 file name} = "%System Root%\Documents and Settings\All Users\Application Data\{random}.exe"

Other System Modifications

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

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
ActiveDesktop
NoChangingWallPaper = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Attachments
SaveZoneInformation = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer
EnableAutoTray = "0"

It adds the following registry entries to disable the Task Manager:

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
DisableTaskMgr = "1"

It modifies the following registry entries to hide files with Hidden attributes:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

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

Other Details

This Trojan deletes the initially executed copy of itself

NOTES:

This malware moves specific files in the following directories:

Operating System major version is 5 (XP, 2000, 2003):

From: %System Root%\Documents and Settings\All Users\Start Menu\
To: %User Temp%\smtmp\1\
From: %User Profile%\Application Data\Microsoft\Internet Explorer\Quick Launch\
To: %User Temp%\smtmp\2\
From: %System Root%\Documents and Settings\All Users\Desktop\
To: %User Temp%\smtmp\4\
Operating System major version is 6 (Vista, 2008, 7)
From: %System Root%\ProgramData\Start Menu\
To: %User Temp%\smtmp\1\
From: %User Profile%\Application Data\Roaming\Microsoft\Internet Explorer\Quick Launch\
To: %User Temp%\smtmp\2\
From: %User Profile%\Application Data\Roaming\Microsoft\Internet Explorer\Quick Launch\User Pinned\TaskBar\
To: %User Temp%\smtmp\3\
From: %System Root%\ProgramData\Desktop\
To: %User Temp%\smtmp\4\

It also modifies the attributes of files found in the affected system into Hidden, to trick the users that the files have been deleted.