Threat Description



Aliases:NetSky.Q, W32/Netsky.Q, I-Worm.Netsky.r, W32/Netsky.Q@mm


The Netsky.Q variant was discovered on March 29th, 2004.This worm spreads in email using different exploits and social engineering. NetSky.Q performs a DDoS against several websites and makes the infected computers beep randomly.


Automatic action

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


You may wish to refer to the Support Community for further assistance. You also may also refer to General Removal Instructions for a general guide on alternative disinfection actions.

Eliminating a Local Network Outbreak

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

Technical Details

System Infection

Upon execution the worm copies its dropper to the Windows Directory as 'SysMonXP.exe', which is added to the registry:

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run] =
"SysMonXP" = "%WinDir%\SysMonXP.exe"

where %WinDir% represents Windows directory name.

The main DLL is placed to the same place with the filename 'firewallogger.txt' alongside with other temporary files used by the worm:


The worm removes several registry values that belong to other worms.

Email Propagation

When collecting addresses NetSky.Q recursively searches through all hard drives and checks the content of files with the following extensions:


This variant of NetSky sends emails that look like error messages from mail servers.

Here's an example of what messages sent by Netsky.Q can look like:

The emails are composed from the following parts:


Delivery Error <recipient@email.address>
 Delivery Failure <recipient@email.address>
 Delivery <recipient@email.address>
 Mail Delivery failure <recipient@email.address>
 Mail Delivery System <recipient@email.address>
 Mail System <recipient@email.address>
 Delivery <recipient@email.address>
 Delivered Message <recipient@email.address>
 Error <recipient@email.address>
 Status <recipient@email.address>
 Failure <recipient@email.address>
 Failed <recipient@email.address>
 Unknown Exception <recipient@email.address>
 Delivery Failed <recipient@email.address>
 Deliver Mail <recipient@email.address>
 Server Error <recipient@email.address>
 Delivery Bot <recipient@email.address>


Mail Delivery - This mail couldn't be displayed
 Mail Delivery Failed - This mail couldn't be represent
 Mail Delivery Error - This mail contains unicode characters
 Mail Transaction Failed - This mail couldn't be converted
 Mail Delivery System - This mail contains binary characters
 Mail Delivery Failure - This mail couldn't be shown.
 Delivery Failure - Invalid mail specification
 Delivery Agent - Translation failed
 ------------- failed message -------------
 The message has been sent as a binary attachment.
 Partial message is available and has been sent as a binary attachment.
 Received message has been attached.
 Message has been sent as a binary attachment.
 Translated message has been attached.
 Received message has been sent as an encoded attachment.
 Modified message has been sent as a binary attachment.
 Note: Received message has been sent as a binary file.

The attachment name is created from one of the following names:

message<random characters>
 msg<random characters>
 mail<random characters>
 data<random characters>

The file extension is either '.pif' or '.zip'. In case of ZIP files the filename inside the ZIP can be one of

data.eml<lots of spaces>.scr
 mail.eml<lots of spaces>.scr
 msg.eml<lots of spaces>.scr
 message.eml<lots of spaces>.scr

The purpose of large number of spaces between the extensions is to the hide the executable extension from the users' eyes, leaving them with the harmless looking '.eml' to open.

The email can contain different endings that attempt to start the attachment or make the user to do so.

  • A link with the format: www.&lt;recipient domain&gt;/inmail/&lt;recipient username&gt;/mread.php?sessionid-&lt;random&gt;
  • An exploit for MS01-020 (IFRAME) to execute the attachment automatically. More information on the vulnerability and patches are available from
  • Plain attachment with '.pif' or '.zip' extension


Between 7th and 12th of April, 2004 NetSky.Q infected computers will perform a Distributed Denial-of-Service attack against the following sites:

On 30th of March, 2004 NetSky.Q will make the infected computer to beep randomly between 5AM and 11AM.


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