Class Email-Worm
Platform VBS

Technical Details

This malicious worm spreads via the Internet in the form of a file attached to infected messages. It is an encoded VBS script of 25562 bytes.

When downloaded Horilka decrypts itself.

It copies itself to the Windows system directory under the name WinSys32dll.vbs, and registers this file in the system registry autorun key.


The virus mass mails all addresses found in the Microsoft Outlook address book.

Characteristics of infected messages:

Message header:


Message body:

�������� ����� vbs ���������� ��� ������ ������� � ������ �� Windows!
��� �������� �������� � ��������, �������������� �� �����.
������������ ������ ������� �� ������-�����, ��� �������� �������������
vb � js ������, ������ ��� ��� ������ ������������� ������������.
���������� ������� ���� � ��������� �� ���������� ������� �������� �����
����������� �������� � ������ ����������.


a VBS script,


Once messages have been sent, the virus sends its author a message which includes all .pwl (password) files found in the Windows directory.

Messages are sent once, when each user’s configuration is loaded.

The virus copies itself to all disks and all directories under the name of Folderdll.vbs and marks these files as hidden.

It searches the Windows folder for files with the following extensions:


Horilka overwrites .vbs files with its own code.

It replaces .jpg, .jpeg, .gif and .bmp files with a GIF format graphic contained in the body of the virus.

It adds the following code to .htm and.html files:

.avc files are overwritten with the phrase:

Vyatka was here

.txt and .doc files are overwritten with the following text:

   ��������� �������! ��� ������ ����� �� ����� - ������� ������.
   Dear friends! You was hacked by virus from Vyatka (situated in deep ass of Russia)
   ..:: Xpi1oT ::..

.mp3 and .wav files are replaced by sound files contained in the body of the worm

If the worm finds any files with a .dbf extension, it deletes them

The virus is coded to display the announcement:


on 11th December every year, and to overwrite the autoexec.bat file with the following text:

   @Windows upgrading your system...
   @Please wait
   format c: /autotest /q /u
   @Please wait...
   format d: /autotest /q /u
   @Your system was hacked by virus from Vyatka (situated in deep ass of Russia)

Once this takes place, the system will reboot, resulting in formating of the C: hard disk.

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