Threat description




NetSky.E (also known as Moodown.E) worm was found on 1st of March 2004 just a few hours after NetSky.D variant. The .E variant is very close to .C variant of the worm. NetSky.E spreads itself in e-mails inside a ZIP archive or as an executable attachment.


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More scanning & removal options

More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.

Eliminating a Local Network Outbreak

If the infection is in a local network, please follow the instructions on this webpage:

Technical Details

Descriptions of previous NetSky variants can be found here:

The differences between NetSky.E variant and the .C variant of the worm are as follows:

  • The worm's file is a PE executable file 24840 bytes long packed with Petite file compressor. The unpacked file's size is over 40 kilobytes.
  • On March 2nd, 2004 the worm constantly beeps with PC speaker from 6:00 to 8:59. Below is the link to the WAV file with the sound that the worm makes:
  • The NetSky.E worm doesn't copy its files to shared folders.
  • The NetSky.E worm variant uses 2 more extensions (.jpg and .gif) for the first extension (if double extension file name is generated) of its attachment:
  • The .E worm variant uses 2 more extensions (.bat and .cmd) for the second extension (if double extension file name is generated) or for the only extension of its attachment:
  • The .E worm variant has 2 more strings ('messagelabs' and 'skynet') added to the list of strings that it uses to avoid sending its e-mails to specified e-mail addresses:
    icrosoft  antivi  ymantec  spam  avp  f-secur  itdefender  orman  cafee  aspersky  f-pro  orton  fbi  abuse  messagelabs  skynet  
  • This variant has a bigger list of subjects:
    Delivery Failed  Status  report  question  trust me  hey  Re: excuse me  read it immediatelly  hi  Re: does it?  Yep  important  hello  dear  Re: unknown  fake?  warning  moin  what's up?  info  Re: information  Here is it  stolen  private?  good morning  illegal...  error  take it  re:  Re: Re: Re: Re:  you?  something for you  exception  Re: hey  excuse me  Re: hi  Re: does it?  Re: important  Re: hello  believe me  Question  denied!  notification  Re: [5664ddff?$??§2]  lol  last chance!  I'm back!  its me  notice!  oh  Announcement  Re: Thank you  Re: Details  Thank you  Details  Re: Approved  Approved  hi, it's me  Thank You very very much  You use illegal...  Your IP was logged  Love is  Re: [censored] registered?  Your request was registered  read now!  Attention  Schedule  You have 1 day left  Re: information  automatic notification  Expired account  automatic responder  Read this message  please read  please reply  Registration confirm  Confirmation  Confirmation Required  Returned Mail  

The .E worm variant just like the .C variant spreads itself in e-mails as a ZIP attachment or as an executable attachment with one of the hardcoded names and single or double extension. A recipient has to unpack the worm's attachment from a ZIP archive and to run it or to run an executable attachment to get infected.

Like the .C variant, NetSky.E worm variant installs itself as WINLOGON.EXE file to Windows folder and creates a startup key for this file in the Registry:

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]  "ICQ Net" = "%windir%\winlogon.exe -stealth"  

where %windir% represents Windows directory.

For more details, please see the description of NetSky.C worm variant.

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