Threat Descriptons



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Worm:W32/Netsky.V does not send itself as an email attachment but uses HTML-encoded emails which exploit a vulnerability known as Microsoft Internet Explorer XML Page Object Type Validation Vulnerability (MS03-040) to try and download and execute itself to a vulnerable host computer.


Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

Netsky.V also performs a Denial-of-Service (DoS) attack against certain sites.

NetSky.V worm was discovered late night on April 14th, 2004. The binary code bears high resemblance to the latest NetSky variant, NetSky.U. Sharing up to approximately 86% of the code.

Some of the worm's text strings are scrambled.


The worm's file is a packed PE executable of length 19432 bytes. Upon execution, NetSky.V copies itself as EastAV.exe file to Windows folder and adds a startup key for this file into System Registry:

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

where %WinDir% represents Windows folder name.

Propagation (email)

Netsky.V arrives in infected emails but does not use an attachment. It sends HTML emails which exploit vulnerability known as Microsoft Internet Explorer XML Page Object Type Validation Vulnerability (MS03-040) that downloads a HTML page to the host.

This HTML page then uses another vulnerbility, Internet Explorer Object Data Remote Execution (MS03-032), that attempts to download the binary part of the worm using command line ftp client, and executes it.

Further information about these vulnerabilities, including a fix, is available from Microsoft:


The email harvesting functionality is identical to the variant NetSky.U.

The messages will have any of the following format:

Subject: Mail Delivery Sytem failure Body: The processing of this message can take a few minutes...

Subject: Mail delivery failed Body: Converting message. Please wait...

Subject: Server Status failure Body: Please wait while loading failed message...

Subject: Gateway Status failure Body: Please wait while converting the message...


Netsky.V has a payload. It performs a DoS (Denial of Service) attack on the following websites from 22nd to 29th of April 2004:

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