TROJ_FAKEAV.BWT

 Analysis by: MarfelTi

 ALIASES:

Microsoft: Trojan:Win32/Cefyns.gen!A; Kaspersky: Trojan-Dropper.Win32.Agent.dtpg

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • 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 poses as an antispyware application that uses pop-up messages displayed on the System Tray to make users think that their systems are infected. This tricks users to purchase the complete version of the said application. It poses as an antispyware application that displays deceptive warnings and misleading scan results. It may also add other applications which it detects upon its installation. 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:

364,544 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

13 Jul 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 files:

  • %System Root%\Documents and Settings\All Users\Start Menu\Programs\Startup\autorun.exe - also detected as TROJ_FAKEAV.BWT
  • %User Profile%\Application Data\printer.exe - also detected as TROJ_FAKEAV.BWT
  • %User Startup%\findfast.exe - also detected as TROJ_FAKEAV.BWT
  • %Windows%\shell.exe - also detected as TROJ_FAKEAV.BWT
  • %System%\printer.exe - also detected as TROJ_FAKEAV.BWT
  • %System%\spoolvs.exe - also detected as TROJ_FAKEAV.BWT
  • %User Temp%\5.bat
  • %User Temp%\6.bat
  • %System%\drivers\etc\st.im
  • %Program Files%\altcmd\altcmd.inf
  • %Program Files%\altcmd\altcmd32.dll
  • %Program Files%\altcmd\uninstall.bat
  • %System%\wowfx.dll
  • %System%\npad.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %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 Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows 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.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

It drops the following copies of itself into the affected system:

  • %System%\{malware file name}.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It creates the following folders:

  • %System%\append.dll
  • %System%\xlib254.dll
  • %Program Files%\altcmd

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

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
Spoolsv = "%System%\spoolvs.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Printer = "%System%\printer.exe"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = Explorer.exe %WINDOWS%\shell.exe

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

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
altcompare

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{2A8D06B4-1B40-009F-E531-629A59080F43}

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
DisableRegistryTools = 1

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

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
ShowedCheckBrowser = Yes

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Check_Associations = No

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Enable Browser Extensions = yes

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
EnableBalloonTips = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoControlPanel = 1

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Windows\Windows Update
NoAutoUpdate = 1

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Windows\Windows Update
NoWindowsUpdate = 1

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Windows\WindowsUpdate\
AU
AutoUpdate = 0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{2A8D06B4-1B40-009F-E531-629A59080F43}\InprocServer32
@ = %Program Files%\altcmd\altcmd32.dll

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%User Profile%\Application Data\printer.exe = %User Profile%\Application Data\printer.exe:*:Enabled:@xpsp2res.dll,-22019

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%System%\printer.exe = %System%\printer.exe:*:Enabled:@xpsp2res.dll,-22019

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%System%\spoolvs.exe = "%System%\spoolvs.exe:*:Enabled:@xpsp2res.dll,-22019"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%Windows%\shell.exe = %Windows%\shell.exe:*:Enabled:@xpsp2res.dll,-22019

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%User Startup%\findfast.exe = %User Startup%\findfast.exe:*:Enabled:@xpsp2res.dll,-22019

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%System Root%\Documents and Settings\All Users\Start Menu\Programs\Startup\autorun.exe = %System Root%\Documents and Settings\All Users\Start Menu\Programs\Startup\autorun.exe:*:Enabled:@xpsp2res.dll,-22019

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%Windows%\system32\winav.exe = %Windows%\system32\winav.exe:*:Enabled:@xpsp2res.dll,-22019

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Profile%\Application Data\printer.exe = %User Profile%\Application Data\printer.exe:*:Enabled:@xpsp2res.dll,-22019

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\printer.exe = "%System%\printer.exe:*:Enabled:@xpsp2res.dll,-22019"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\spoolvs.exe = "%System%\spoolvs.exe:*:Enabled:@xpsp2res.dll,-22019"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\shell.exe = %Windows%\shell.exe:*:Enabled:@xpsp2res.dll,-22019

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Startup%\findfast.exe = %User Startup%\findfast.exe:*:Enabled:@xpsp2res.dll,-22019

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System Root%\Documents and Settings\All Users\Start Menu\Programs\Startup\autorun.exe = %System Root%\Documents and Settings\All Users\Start Menu\Programs\Startup\autorun.exe:*:Enabled:@xpsp2res.dll,-22019

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\system32\winav.exe = %Windows%\system32\winav.exe:*:Enabled:@xpsp2res.dll,-22019

Rogue Antivirus Routine

This Trojan poses as an antispyware application that uses pop-up messages on the System Tray to make users think that their systems are infected. This tricks users to purchase the complete version of the said application.

It poses as an antispyware application that displays deceptive warnings and misleading scan results. It may also add other applications which it detects upon its installation.

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.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.286.11

FIRST VSAPI PATTERN DATE:

13 Jul 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.BWT

[ 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

Enable Registry Editor

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = Explorer.exe %WINDOWS%\shell.exe
      To: Explorer.exe

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
%System%\append.dll
%System%\xlib254.dll
%Program Files%\altcmd

Step 6

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAKEAV.BWT. 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.


Did this description help? Tell us how we did.