TROJ_FAKEAV.TY


 ALIASES:

Microsoft: Trojan:Win32/FakeSysdef; Kaspersky: Trojan-Dropper.Win32.FrauDrop.xysa; Mcafee: Generic FakeAlert.by

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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.

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.

  TECHNICAL DETAILS

File Size:

457,216 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

12 Sep 2011

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 file name}.exe

(Note: %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

(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.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random file name} = "%System Root%\Documents and Settings\All Users\Application Data\{random file name}.exe"

Other System Modifications

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

HKEY_CURRENT_USER\Software
75fa38b7-8b94-4995-ad32-52e938867954 = ""

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Associations
LowRiskFileTypes = ".zip;.rar;.nfo;.txt;.exe;.bat;.com;.cmd;.reg;.msi;.htm;.html;.gif;.bmp;.jpg;.avi;.mpg;.mpeg;.mov;.mp3;.m3u;.wav;.scr;"

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

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

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

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

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

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Download
CheckExeSignatures = "no"

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

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

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

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 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.

NOTES:

This malware moves specific files on 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 then sets the attributes of all folders and files on the system to Hidden. It also changes the desktop wallpaper to black. Certain error messages prompt the users that an error is detected and reboots the machine. These behaviors make the user think that the system has errors.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.422.07

FIRST VSAPI PATTERN DATE:

12 Sep 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Identify and terminate files detected as TROJ_FAKEAV.TY

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random file name} = "%System Root%\Documents and Settings\All Users\Application Data\{random file name}.exe"
  • In HKEY_CURRENT_USER\Software
    • 75fa38b7-8b94-4995-ad32-52e938867954 = ""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\ActiveDesktop
    • NoChangingWallPaper = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Associations
    • LowRiskFileTypes = ".zip;.rar;.nfo;.txt;.exe;.bat;.com;.cmd;.reg;.msi;.htm;.html;.gif;.bmp;.jpg;.avi;.mpg;.mpeg;.mov;.mp3;.m3u;.wav;.scr;"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Attachments
    • SaveZoneInformation = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System
    • DisableTaskMgr = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • NoDesktop = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system
    • DisableTaskMgr = "1"

Step 4

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Download
    • From: CheckExeSignatures = "no"
      To: CheckExeSignatures = "yes"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "0"
      To: Hidden = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: ShowSuperHidden = "0"
      To: ShowSuperHidden = "1"

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAKEAV.TY. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

NOTES:

To unhide the files hidden by this malware, perform the following steps:

  1. Open a Command Prompt.

    For Windows 2000, Windows XP, and Windows Server 2003 users:
    Click Start > Run, type CMD in the text box provided, and then press Enter.

    For Windows Vista and Windows 7 users:
    Click the Start button, type CMD in the Search input field then press Enter.

  2. For every drive in the computer, type the following command:
    • attrib -h {drive letter}:\*.* /s /d
  3. Close Command Prompt. Type exit then press Enter.

To Restore Files to its Original Location:

Open %User Temp%\smtmp and copy the files as follows:

If operating system major version is 5 (XP, 2000, 2003):
From: %User Temp%\smtmp\1\
To: %System Root%\Documents and Settings\All Users\Start Menu\

From: %User Temp%\smtmp\2\
To: %User Profile%\Application Data\Microsoft\Internet Explorer\Quick Launch\

From: %User Temp%\smtmp\4\
To: %System Root%\Documents and Settings\All Users\Desktop\

If operating system major version is 6 (Vista, 2008, 7)
From: %User Temp%\smtmp\1\
To: %System Root%\ProgramData\Start Menu\

From: %User Temp%\smtmp\2\
To: %User Profile%\Application Data\Roaming\Microsoft\Internet Explorer\Quick Launch\

From: %User Temp%\smtmp\3\
To: %User Profile%\Application Data\Roaming\Microsoft\Internet Explorer\Quick Launch\User Pinned\TaskBar\

From: %User Temp%\smtmp\4\
To: %System Root%\ProgramData\Desktop\

After moving the files, delete the folder %User Temp%\smtmp.


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