Category: Malware

Type: Worm

Aliases: Antinny, W32.HLLW.Antinny


This worm will spread though the P2P network of the Japanese software Winny P2P. The file length is 651264.


Automatic action

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

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Technical Details

When the worm is executed it will display a fake error Window with Japanese text.

The worm incorporates DLLs within its body, with the purpose of handling LHA and ZIP compressed files. Those DLLs amount for most of the worm's length.

The DLLs will be copied to the Windows' system folder. Their names and lengths follow:

UNLHA32.DLL, 254.464 bytes
 135.168 bytes
 61.440 bytes

all of those components are harmless by themselves.

The worm copies itself to the Windows' system folder, the full path of the file is:


and an entry in the Windows' Registry is added, aiming at having the worm start when Windows does.


"ara-key" = %WinSysDir%\ny.exe -StartUp

It will then copy itself again, with the same name "ny.exe", to the user's default folder for temporary files.

The worm will attempt to find the Winny P2P software by searching the system for the application's main executable "Winny.exe", once found it will copy itself to the folder designated by the user as the one containing shared content. This will make the worm available for download to other users of the P2P network.