I-Worm.LoveLetter

I-Worm.LoveLetter is Internet worm written in the scripting language "Visual Basic Script" (VBS). It works only on computers on which the Windows Scripting Host (WSH) is installed. In Windows 98 and Windows 2000, WHS is installed by default. The worm performs destructive actions and sends its copy bye E-mail.

Destructive actions

After starting from the VBS file the worm searches all files on all local and mapped network drivers. For some extensions of filenames the worm does the following:

VBS, VBE:: Overwrites files with the worm body.
JS, JSE, CSS, VSH, HST, HTA:: Creates a new file with original filename and extention .VBS and deletes original file.
JPG, JPEG:: Creates new file with extention .VBS (adds this extention to old file name and extention) (i.e. PIC1.JPG.VBS). Writes worm body to it and deletes original file.
MP2, MP3:: Creates a new file with extention .VBS (adds to old file name, see above for details). It writes its body to it and sets thef file attribute "hidden" to the original file.
MIRC32.EXE, MLINK32.EXE, SCRIPT.INI, MIRC.HLP, MIRC.INI:: If one of these files was found the worm creates the file SCRIPT.INI in the directory were one of the above files resides.

The worm also creates some files with its body in system directory.

 MSKERNEL32.VBS, WIN32DLL.VBS, LOVE-LETTER-FOR-YOU.TXT.VBS

It sets appropriates keys in the system registry (Automatic run keys) with full names of files:

 MSKernel32.vbs, Win32DLL.vbs

It adds system registry keys:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run\MSKernel32
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices\Win32DLL

Spreading via E-mail

The worm sends itself via E-mail. To achieve this the worm sends itself to each address from address book. It works only when the email program Outlook 97/98/2000 is installed.

The letter's subject:

 ILOVEYOU

Message body:

 kindly check the attached LOVELETTER coming from me.

Attached file name:

 LOVE-LETTER-FOR-YOU.TXT.vbs

The virus creates a HTML dropper in Windows system directory. The HTML dropper displays the message:

 This HTML file need ActiveX Control
 To Enable to read this HTML file
 - Please press 'YES' button to Enable ActiveX

After this the dropper creates the MSKERNEL32.VBS with the worm body and sets it for auto execution from system registry.