Arrival Details
This worm 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 worm creates the following folders:
- %System%\dllchache
- %Program Files%\Microsoft
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Blank AntiViri = "%System Root%\AUT0EXEC.BAT StartUp"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Secure64 = "%System%\dllcache\Regedit32.com StartUp"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Secure32 = "%System%\dllcache\Shell32.com StartUp"
It modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe, %System%\M5VBVM60.EXE StartUp "
(Note: The default value data of the said registry entry is %Windows%\system32\userinit.exe,.)
Other System Modifications
This worm adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
CabinetState
FullPathAddress = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
CabinetState
FullPath = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "1"
(Note: The default value data of the said registry entry is 2.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = "1"
(Note: The default value data of the said registry entry is 1.)
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot
AlternateShell = "%System Root%\AUT0EXEC.BAT StartUp"
(Note: The default value data of the said registry entry is cmd.exe.)
Dropping Routine
This worm drops the following files:
- cmgr.exe
- %System Root%\(Read Me)Pendekar Blank.txt
- %Program Files%\Microsoft\px8.tmp
- %User Temp%\ie5C92.tmp
- %System%\dllChache\msvbvm60.dll
- %System Root%\msvbvm60.dll
- %System%\dllcache\msvbvm60.dll
- %System%\dllChache\Empty.jpg
- %System%\dllChache\Blank.doc
- %System%\dllChache\Zero.txt
- %System%\dllChache\Hole.zip
- %System%\dllChache\Unoccupied.reg
- %System Root%\AUT0EXEC.BAT
- %System%\rund1132.exe
- %System%\dllcache\Regedit32.com
- %System%\dllcache\Shell32.com
- %System%\M5VBVM60.EXE
- %System%.exe
- %System%\dllchache.exe
- %Program Files%\Microsoft\WaterMark.exe
This report is generated via an automated analysis system.
Step 1
Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.
Step 2
Identify and delete files detected as WORM_BRONTOK.BAS using either the Startup Disk or Recovery Console
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To identify and delete the malware/grayware file:
• On Windows XP and Server 2003 systems:
- Scan your computer with your Trend Micro product and then take note of the names of the malware/grayware files detected.
- Click Start>Run. In the Open input box, type secpol.msc and press Enter.
- In the left panel, double-click Local Policies>Security Options.
- In the right panel, double-click Recovery Console: Allow floppy copy and access to all drives and folders.
- Select Enabled and click OK.
- Insert the Windows Installation CD into the CD drive, then restart your computer.
- When prompted, press any key to boot from the CD.
- On the main menu, type r to go to the Recovery Console.
- Type the number that corresponds to the drive and directory that contains Windows (usually C:\WINDOWS) and press Enter.
- Type the Administrator password and press Enter.
- In the input box, type the following then press Enter:
SET AllowAllPaths = TRUE
del "{malware/grayware path and file name}" - Type exit and press Enter to restart the system normally.
• On Windows Vista and 7 systems:
- Scan your computer with your Trend Micro product and then take note of the names of the malware/grayware files detected.
- Insert your Windows Installation DVD in the DVD drive, then Press the restart button.
- When prompted, press any key to boot from the CD.
- Depending on your Windows Installation DVD, you might be required to select the installation language. Then on the Install Windows window, choose your language, locale, and keyboard layout or input method. Click Next, then click Repair your computer.
- Select Use recovery tools that can help fix problems starting Windows. Select your installation of Windows. Click Next.
- If the Startup Repair window appears, click Cancel, Yes, then Finish.
- In the System Recovery Options window, click Command Prompt.
- In the Command Prompt window, type the following then press Enter:
BootRec.exe /fixmbr
del "{malware/grayware path and file name}" - Type exit and press Enter to close the Command Prompt window.
- Click Restart to restart the system normally.
Step 3
Delete this registry value
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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\CurrentVersion\Run
- Blank AntiViri = "%System Root%\AUT0EXEC.BAT StartUp"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Secure64 = "%System%\dllcache\Regedit32.com StartUp"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Secure32 = "%System%\dllcache\Shell32.com StartUp"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\CabinetState
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
To delete the registry value this malware/grayware created:
- Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
- In the left panel, double-click the following:
HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows>CurrentVersion>Run - In the right panel, locate and delete the entry:
Blank AntiViri = "%System Root%\AUT0EXEC.BAT StartUp" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Run - In the right panel, locate and delete the entry:
Secure64 = "%System%\dllcache\Regedit32.com StartUp" - Again In the right panel, locate and delete the entry:
Secure32 = "%System%\dllcache\Shell32.com StartUp" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Explorer>CabinetState - In the right panel, locate and delete the entry:
FullPathAddress = "1" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Explorer>Advanced - In the right panel, locate and delete the entry:
ShowSuperHidden = "0" - Close Registry Editor.
Step 4
Restore these modified registry values
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[ back ]
Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\CabinetState
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: Hidden = "1"
To: Hidden = ""2""
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: HideFileExt = "1"
To: HideFileExt = ""1""
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot
- From: AlternateShell = "%System Root%\AUT0EXEC.BAT StartUp"
To: AlternateShell = ""cmd.exe""
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: Userinit = "%System%\userinit.exe, %System%\M5VBVM60.EXE StartUp "
To: Userinit = ""%Windows%\system32\userinit.exe,""
To restore registry values this malware/grayware modified:
- Open Registry Editor. To do this:
- On Windows 2000, XP, and Server 2003:
Click Start>Run, type REGEDIT in the text box provided, and then press Enter. - On Windows Vista and 7:
Click the Start button, type REGEDIT in the Search input field then press Enter.
- In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Explorer>CabinetState - In the right panel, locate the registry value:
FullPath = "1" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Explorer>Advanced - In the right panel, locate the registry value:
Hidden = "1" - Right-click on the value name and choose Modify. Change the value data of this entry to:
Hidden = "2" - Again In the right panel, locate the registry value:
HideFileExt = "1" - Right-click on the value name and choose Modify. Change the value data of this entry to:
HideFileExt = "1" - In the left panel, double-click the following:
HKEY_LOCAL_MACHINE>SYSTEM>ControlSet001>Control>SafeBoot - In the right panel, locate the registry value:
AlternateShell = "%System Root%\AUT0EXEC.BAT StartUp" - Right-click on the value name and choose Modify. Change the value data of this entry to:
AlternateShell = "cmd.exe" - In the left panel, double-click the following:
HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Winlogon - In the right panel, locate the registry value:
Userinit = "%System%\userinit.exe, %System%\M5VBVM60.EXE StartUp " - Right-click on the value name and choose Modify. Change the value data of this entry to:
Userinit = "%Windows%\system32\userinit.exe," - Close Registry Editor.
Step 5
Search and delete these components
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There may be some components 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.
- cmgr.exe
- %System Root%\(Read Me)Pendekar Blank.txt
- %Program Files%\Microsoft\px8.tmp
- %User Temp%\ie5C92.tmp
- %System%\dllChache\msvbvm60.dll
- %System Root%\msvbvm60.dll
- %System%\dllcache\msvbvm60.dll
- %System%\dllChache\Empty.jpg
- %System%\dllChache\Blank.doc
- %System%\dllChache\Zero.txt
- %System%\dllChache\Hole.zip
- %System%\dllChache\Unoccupied.reg
- %System Root%\AUT0EXEC.BAT
- %System%\rund1132.exe
- %System%\dllcache\Regedit32.com
- %System%\dllcache\Shell32.com
- %System%\M5VBVM60.EXE
- %System%.exe
- %System%\dllchache.exe
- %Program Files%\Microsoft\WaterMark.exe
To manually delete a malware/grayware component from an affected system:
• For Windows 2000, Windows XP, and Windows Server 2003:
- Right-click Start then click Search....
- In the Named input box, type:
- cmgr.exe
- %System Root%\(Read Me)Pendekar Blank.txt
- %Program Files%\Microsoft\px8.tmp
- %User Temp%\ie5C92.tmp
- %System%\dllChache\msvbvm60.dll
- %System Root%\msvbvm60.dll
- %System%\dllcache\msvbvm60.dll
- %System%\dllChache\Empty.jpg
- %System%\dllChache\Blank.doc
- %System%\dllChache\Zero.txt
- %System%\dllChache\Hole.zip
- %System%\dllChache\Unoccupied.reg
- %System Root%\AUT0EXEC.BAT
- %System%\rund1132.exe
- %System%\dllcache\Regedit32.com
- %System%\dllcache\Shell32.com
- %System%\M5VBVM60.EXE
- %System%.exe
- %System%\dllchache.exe
- %Program Files%\Microsoft\WaterMark.exe
- In the Look In drop-down list, select My Computer then press Enter.
- Once located, select the file then press SHIFT+DELETE to delete it.
- Repeat the said steps for all files listed.
• For Windows Vista and Windows 7 users:
- Click Start>Computer.
- In the Search input box, type:
- cmgr.exe
- %System Root%\(Read Me)Pendekar Blank.txt
- %Program Files%\Microsoft\px8.tmp
- %User Temp%\ie5C92.tmp
- %System%\dllChache\msvbvm60.dll
- %System Root%\msvbvm60.dll
- %System%\dllcache\msvbvm60.dll
- %System%\dllChache\Empty.jpg
- %System%\dllChache\Blank.doc
- %System%\dllChache\Zero.txt
- %System%\dllChache\Hole.zip
- %System%\dllChache\Unoccupied.reg
- %System Root%\AUT0EXEC.BAT
- %System%\rund1132.exe
- %System%\dllcache\Regedit32.com
- %System%\dllcache\Shell32.com
- %System%\M5VBVM60.EXE
- %System%.exe
- %System%\dllchache.exe
- %Program Files%\Microsoft\WaterMark.exe
- Once located, select the file then press SHIFT+DELETE to delete it.
- Repeat the said steps for all files listed.
*Note: Read the following Microsoft page if these steps do not work on Windows 7.
Step 6
Search and delete these folders
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[ back ]
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%\dllchache
- %Program Files%\Microsoft
To delete malware/grayware/spyware folders:
- Right-click Start then click Search... or Find..., depending on the version of Windows you are running.
- In the Named input box, type:
- %System%\dllchache
- %Program Files%\Microsoft
- In the Look In drop-down list, select My Computer, then press Enter.
- Once located, select the folder then press SHIFT+DELETE to permanently delete the folder.
- Repeat steps 2 to 4 for the remaining folders:
- %System%\dllchache
- %Program Files%\Microsoft
Step 7
Scan your computer with your Trend Micro product to delete files detected as WORM_BRONTOK.BAS. 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.
