Nachi worm

The Nachi worm is a computer worm that exploits a vulnerability in the Microsoft RPC service similar to the Blaster worm. However unlike Blaster, it tries to help the user by downloading and installing security patches from Microsoft. Though even as it implies no harm, it can increase network traffic, reboot the infected computer, and more importantly—it operates without consent.

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What You Should Know About the Nachi Worm