Threat description




This type of worm is embedded in an e-mail attachment, and spreads using the infected computer's e-mailing networks.


Automatic action

Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.

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Technical Details

Email-Worm:VBS/Gedza.B is a very nasty worm which performs a variety of date-triggered actions every month. It is particularly troublesome because, in addition to spreading by e-mail attachments like most e-mail worms, it is also coded to be able to use numerous other vectors, including removable media and Peer-to-Peer (P2P) networks.

Whether the individual's system is infected automatically, or requires the individual to perform some action first, depends on how the worm is propagated. For example, if the worm comes in contact with the recipient's system over a network, it does not require any action from the recipient to infect the system; but if it arrives through e-mail or a Word document, the recipient must open the e-mail or document to infect the system.

Upon execution, the worm will install various files on the system, including an EXE file which is an antivirus program disabler and a zipped copy of the worm itself, which is the version sent out to e-mail addresses harvested from the infected system. It also makes a variety of registry key changes designed to allow the malware to run on every startup; to lower the Excel and Word programs security levels; and to disable further registry editing.

Once installed, the worm appears to launch an innocuous image of Avril Lavigne. On certain dates every month however, the worm will perform a certain action, with different actions performed on different dates.

On the 3rd of every month:

On the 11th of every month:

On the 19th of every month:

On the 26th of every month:

On the 29th of every month:

The worm causes the user's browser to open at the website

In addition to the various annoying date-triggered actions, the worm causes trouble by spreading through a exceptionally large number of ways.

1) It can spread through disks and removable drives by:

  • Overwriting files with itself- Writing VBScript codes if the file extension ends with .vbs or .vbe- Writing JavaScript codes if the file extension ends with .js or .jse
  • Appending itself to files- Appending itself to the end of HTA, HTM, HTML, PHP, SHTM and SHTML files, as well as other website related extensions
  • Changing zip content- Inserting a copy of itself into zip archives

2) It can spread through e-mail by:

  • Creating a template in Outlook
  • Sending itself out using its own mail application

3) It can spread through Peer-to-Peer (P2P) networks by:

  • Copying infected zip files to P2P shared folders with interesting names eg. "" , "AVP Antivirus Pro Key" , "warcraft 3" and etc

4) It can spread through networks by:

  • Going through random IPs and using a set of common usernames and passwords to try and gain access to network folders
  • Once the worm has access to network folders, it infects them

5) It can spread through IIS servers by:

  • Hosting an ISS server and creating asp for it

6) It can spread through Excel and Word by:

  • Creating macros as normal templates for Word and Excel
  • Disabling alerts and lower macro security

7) It can spread through mIRC by:

  • Editing mIRC.ini and creating an IRC script to propagate itself.
File System Changes

Creates these files:

  • %System%\AvrilLavigne.jpg
  • %System%\iw.dat
  • %System%\iwn.dat
  • %System%\ix.dat
  • %System%\ixn.dat
  • %System%\pkzip.exe
  • %System%\regsrv.exe
  • %System%\sendi.exe

Modified these files:

  • %System%\File.vbs
  • %System%\FILEZIP.ZIP
  • %System%\GEDZAC.vbs
  • %System%\Israfel.vbs
  • %System%\
  • %System%\
  • %System%\Template.htm
  • %System%\
  • [windows]run = %System%\
  • [boot]shell=Explorer.exe %System%\
Registry Modifications

Sets these values:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Kernel21 = %System%\
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Israfel = %System%\Israfel.vbs
  • HKEY_CLASSES_ROOT\winfile\DefaultIcon = %SystemRoot%\System32\shell32.dll,-154
  • HKEY_CLASSES_ROOT\winfile\Shell\Open\Command = %System%\WScript.exe %1" %*"
  • HKEY_CURRENT_USER\Identities\xxx\Software\Microsoft\Outlook Express\xxx\Mail\Message Send HTML = dword:00000001
  • HKEY_CURRENT_USER\Identities\xxx\Software\Microsoft\Outlook Express\xxx\Mail\Compose Use Stationery = dword:00000001
  • HKEY_CURRENT_USER\Identities\xxx\Software\Microsoft\Outlook Express\xxx\Mail\Wide Stationery Name = %System%\Template.htm
  • HKEY_CURRENT_USER\Identities\xxx\Software\Microsoft\Outlook Express\xxx\Mail\Stationery Name = %System%\Template.htm
  • HKEY_CURRENT_USER\Software\Microsoft\WindowsNT\CurrentVersion\Policies\System\DisableRegistryTools = dword:00000001
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\DisableRegistryTools = dword:00000001
  • HKEY_USERS\xxx\Software\Microsoft\Office\xxx\Excel\Security\Level = dword:00000001
  • HKEY_USERS\xxx\Software\Microsoft\Office\xxx\Word\Security\Level = dword:00000001

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