CSS Internet News Report VBS/LoveLetter VBScript Worm
VBS/LoveLetter VBScript Worm
http://www.cert.org/current/
The morning of 5/4/2000, we began to receive numerous reports of a
VBScript worm being called "Love Letter" circulating in the wild. Early
reports we have received indicate this is not a hoax. Reports indicate
the worm is distributed via e-mail with the following characteristics:
Subject: ILOVEYOU
The body of the message contains:
kindly check the attached LOVELETTER coming from me
A file attachment is included, named:
LOVE-LETTER-FOR-YOU.TXT.vbs
More information is available from:
http://www.f-secure.com/v-descs/love.htm
If your site has been affected by VBS/LoveLetter, we would appreciate
knowing the scope of the infection at your site. Please let us know by
submitting an incident report using our Incident Reporting Form, and be
sure to specify how many hosts were affected.
http://www.cert.org/ftp/incident_reporting_form
We will provide updates as we gather more information.
F-Secure Virus Information Pages
http://www.f-secure.com/v-descs/love.htm
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NAME:LoveLetter
VBS/LoveLetter is a VBScript worm. It spreads thru email as a chain
letter.
The worm uses the Outlook e-mail application to spread. LoveLetter is
also a overwriting VBS virus, and it spreads itself using mIRC client as
well.
When it is executed, it first copies itself to Windows System directory
as:
- MSKernel32.vbs
- LOVE-LETTER-FOR-YOU.TXT.vbs
and to Windows directory:
- Win32DLL.vbs
Then it adds itself to registry, so it will be executed when the system
is restarted. The registry keys that it adds are:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run\MSKernel32
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run\MSKernel32
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices\Win
32DLL
Next the worm replaces the Internet Explorer home page with a link that
points to an executable program, "WIN-BUGSFIX.exe". If the file is
downloaded, the worm adds this to registry as well; causing that the
program will be executed when the system is restarted.
The executable part that the LoveLetter worm downloads from the web is a
password stealing trojan. On startup the trojan tries to find a hidden
window named 'BAROK...'. If it is present, the trojan exits immediately,
if not - the main routine takes control. The trojan checks for the
WinFAT32 subkey in the following Registry key:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
If the WinFAT32 subkey key is not found, the trojan creates it, copies
itself to \Windows\System\ directory as WINFAT32.EXE and then runs the
file from that location. The above registry key modification makes the
trojan become active every time Windows starts.
Then the trojan sets Internet Explorer startup page to 'about:blank'.
After that the trojan tries to find and delete the following keys:
Software\Microsoft\Windows\CurrentVersion\Policies\Network\HideSharePwds
Software\Microsoft\Windows\CurrentVersion\Policies\Network\DisablePwdCaching
Software\Microsoft\Windows\CurrentVersion\Policies\Network\DisablePwdCaching
.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Policies\Network\HideShar
ePwds
ePwds
.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Policies\Network\DisableP
wdCaching
Then trojan registers a new window class and creates a hidden window
titled 'BAROK...' and remains resident in Windows memory as a hidden
application.
Immediately after startup and when timer counters reaches the certain
values, the trojan loads MPR.DLL library, calls WNetEnumCashedPasswords
function and sends stolen RAS passwords and all cached Windows passwords
to [log in to unmask] e-mail address that most likely belongs to
trojan's author. The trojan uses the 'smpt.super.net.ph' mail server to
send e-mails. The e-mail's subject is 'Barok...
email.passwords.sender.trojan'.
There's the author's copyright message inside the trojan's body:
barok ...i hate go to school suck ->by:spyder @Copyright (c) 2000
GRAMMERSoft Group >Manila,Phils.
There are also some encrypted text messages in the trojan's body used
for its internal purposes.
After that, the worm creates a HTML file, "LOVE-LETTER-FOR-YOU.HTM", to
the Windows System directory. This file contains the worm, and it will
be sent using mIRC whenever the user joins an IRC channel.
Then the worm will use Outlook to mass mail itself to everyone in each
address book. The message that it sends will be as follows:
Subject: ILOVEYOU
Body: kindly check the attached LOVELETTER coming from me.
Attachment: LOVE-LETTER-FOR-YOU.TXT.vbs
LoveLetter sends the mail once to each recipient. After a mail has been
sent, it adds a marker to the registry and does not mass mail itself any
more.
The virus then searches for certain filetypes on all folders on all
local and remote drives and overwrites them with its own code. The files
that are overwritten have either "vbs" or "vbe" extension.
For the files with the following extensions: ".js", ".jse", ".css",
".wsh", ".sct" and ".hta", the virus will create a new file with the
same name, but using the extension ".vbs". The original file will be
deleted.
Next the the virus locates files with ".jpg" and ".jpeg" extension, adds
a new file next to it and deletes the original file. Then the virus
locates ".mp3" and ".mp2" files, creates a new file and hides the
original file. For above two cases, the new files created will have the
original name added with the extension ".vbs". For example, a picture
named "pic.jpg" will cause a new file called "pic.jpg.vbs" to be
created.
LoveLetter was found globally in-the-wild on May 4th, 2000. It looks
like the virus is Philippine origin. At the beginning of the code, the
virus contains the following text:
rem barok -loveletter(vbe) <i hate go to school>
rem by: spyder / [log in to unmask] / @GRAMMERSoft Group /
Manila,Philippines
[Analysis: Katrin Tocheva, Mikko Hypponen, Alexey Podrezov and Sami
Rautiainen, F-Secure]
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