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Virus:VBS/Small.Sasan.A
Date discovered:08/11/2007
Type:Worm
In the wild:No
Reported Infections:Low
Distribution Potential:Low to medium
Damage Potential:Low to medium
Static file:Yes
File size:10.164 Bytes
MD5 checksum:efe528483fd3c6ed75a8c1e016026e10
VDF version:7.00.00.185
IVDF version:7.00.00.192 - Thursday, November 8, 2007

 General Method of propagation:
   • Mapped network drives


Aliases:
   •  Sophos: VBS/Sasan-Fam
   •  Grisoft: VBS/LoveLetter


Platforms / OS:
   • Windows 95
   • Windows 98
   • Windows 98 SE
   • Windows NT
   • Windows ME
   • Windows 2000
   • Windows XP
   • Windows 2003


Side effects:
   • Disable security applications
   • Drops a file
   • Registry modification


Right after execution it runs a windows application which will display the following window:





   Merlin: Huh..Banjarbaru makin panas aja ya
   Merlin: It's now time to work. Jangan ngerumpi mulu..
   Merlin: Hope you enjoy today.
   Merlin: Komputernya ta dinginin dulu OK
   Merlin: Cape dech, Bye Bye Ahh!

 Files It copies itself to the following locations:
   • %sysdir%\ctfmon.exe.vbe
   • %drive%\Thumbs.db.vbe
   • %drive%\%deleted file%.vbe

The following directory is searched:
   • %drive%\

The following file types is payed attention to:
   • .doc
   • .docx
   • .xls
   • .ppt
   • .jpg
   • .bmp
   • .3gp
   • .rm

The original file is erased afterwards.



The following file is created:

%drive%\autorun.inf This is a non malicious text file with the following content:
   • [autorun]
     shellexecute=wscript.exe Thumbs.db.vbe




It tries to executes the following file:

– Filename:
   • %sysdir%\cmd.exe
using the following command line arguments: shutdown -s -t 00 -f -m

 Registry The following registry key is added in order to run the process after reboot:

– [HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
   • CTFMon="%sysdir%\ctfmon.exe.vbe"



The following registry keys are added:

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\
   Advanced]
   • Hidden=dword:00000002

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\cmd.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\install.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\msconfig.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\regedit.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\AVG Free.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\regedt32.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\RegistryEditor.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\setup.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\setup32.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\AVG 7.5.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\rstrui.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\PCMAV.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\PCMAV-CLN.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\PCMAV-RTP.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\ANSAV.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\AVG.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\run.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\avgw.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\AVG Free Edition.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\AVG Free Edition Test Centre.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\Avg Free Control Center.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\vbren.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\Kaspersky.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\Kaspersky 6.0.2.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\PC Tools.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\AVAST.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\CAV.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\McAfee.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\McAfee VirusScan.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\Symantec.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\Norman.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\TuneUp Utilities.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\TuneUp Utilities 2006.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\TuneUp Utilities 2007.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\Stars TuneUp Utilities.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\Fix the BRONTOK.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\NOD32.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\HijackThis.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\hijack.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\navw32.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\griso.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\procexp.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\avp.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\samdAV 3.3.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\samdAV 3.2.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\smadAV.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\
   Avira Antivir PersonalEdition Classic.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\avcenter.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\AntiVir.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\Avira.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\procmon.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\filemon.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\DiskCleaner.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\RegistryCleaner.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\StarUpManager.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\TuneUp RescueCenter.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\RescueCenter.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\TuneUp RegistryEditor.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\avgcc.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\VPTray.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\VPDN_LU.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\VPC32.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\TweakUI for Windows XP.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\TweakUI.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\MSConfig CleanUp.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\CCleaner.exe]
   • Debugger="notepad.exe"

– [HKLM\Software\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\Itegrator.exe]
   • Debugger="notepad.exe"



The following registry keys are changed:

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer]
   New value:
   • NoDriveTypeAutoRun=dword:00000000
   • NoFind=dword:00000001
   • NoFolderOptions=dword:00000001
   • NoRun=dword:00000001
   • NoViewContextMenu=dword:00000001

– [HKCR\VBEFile\DefaultIcon]
   New value:
   • (Default)=shell32.dll,-50

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced]
   Old value:
   • Hidden= %user defined settings%
     HideFileExt= %user defined settings%
     SuperHidden= %user defined settings%
   New value:
   • Hidden=dword:00000000
     HideFileExt=dword:00000001
     SuperHidden=dword:00000000

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System]
   Old value:
   • DisableRegistryTools= %user defined settings%
     DisableTaskMgr= %user defined settings%
   New value:
   • DisableRegistryTools=dword:00000001
     DisableTaskMgr=dword:00000001

 File details Programming language:
The malware program was written in Visual Basic.


Runtime packer:
In order to aggravate detection and reduce size of the file it is packed with a runtime packer.

Description inserted by Monica Ghitun on Friday, November 9, 2007
Description updated by Monica Ghitun on Friday, November 9, 2007

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