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RingZero, Ring0, Trojan.PSW.Ring


RingZero is a trojan. It can arrive as an executable email attachment. This trojan first arrived attached to a Winsock Version Checker program. The pure trojan has 2 parts - an executable part (an EXE file packed with Petite file compressor) and a small VXD part attached to executable. The trojan can be also attached to any Windows executable.


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 the trojan is run it first installs itself to system. It detaches itself from a file it came with and writes 2 files to \Windows\System\ directory. One file is always RING0.VXD and the other can have different names:


Also the third file called A.EXE could be created. Then the trojan makes necessary modifications so it could be always run with Windows. Being active the trojan scans Internet for proxy servers and if such server is found the the trojan writes its address to ITS.DAT (or to differently named DAT file) and sends this file to a website with the following address: (now it is removed for security reasons).

It seems that the trojan was purposely created to send data to that server. The idea was most likely to collect information about all proxy servers on Internet and compile it into a database.

The trojan doesn't have any other payload and it doesn't work on Windows NT.