Threat Descriptons



Category :


Type :


Aliases :

Email-Worm.Win32.Atak.h,, I-Worm.Atak.h, Atak.h


A new variant of the Atak worm was found on 15th of December 2004. The worm spreads in emails that have a subject "Merry X-Mas!" or "Happy New Year!".


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

When run the worm creates a mutex named "2k5" to avoid running more than once simultaneously.

The worm copies itself as:


where %WinSysDir% is Windows System folder, for example 'C:\Windows\System32\' on a default installation of Windows XP.

The worm adds an entry to the win.ini file using the Windows API call WritePrivateProfileStringA from the Kernel32.dll. The entry will look like this:


As win.ini is not supported by Windows NT, 2000 and XP, on these operating system the changes will be added to the Registry. As as result Windows will start the worm on every time it boots.

Email spreading

Atak.h worm will collect email address from files with certain extensions on all hard disks and RAM drives from C: to Z. Files with the following extensions will be checked:


The worm has its own SMTP engine which it uses to send infected emails. The messages sent by the worm will have one of the following subjects:

Merry X-Mas!
Happy New Year!

The worm uses one of the following message body texts:

Happy New year and wish you good luck on next year!
Merry Christmas! Happy New Year! 2005 will be the beginning!

The worm attaches itself to an infected message using a name combined of the following extensions:


For example the name can be scr.pif or scr.scr. In some cases the worm can send itself in a ZIP archive.

Here's a screenshot of an infected message:

Peace of mind against online threats

F-Secure Total is a security suite that protects all your phones and computers in real time, 24/7 and with award-winning accuracy. Read more about Total and try it free for 30 days, no credit card required.

More Support


Ask questions in our Community .

User Guides

Check the user guide for instructions.

Contact Support

Chat with or call an expert.

Submit a Sample

Submit a file or URL for analysis.