An 18-year-old German youth was arrested on Friday after the police conducted a raid on his house in Rotenburg, in the northern state of Lower Saxony.
The teenager, whom the police did not name, confessed to creating the Sasser worm, which infected millions of computers worldwide.
The Sasser worm struck on May 1, and in less than a week affected thousands of companies and as many as 18 million computers worldwide.
The Sasser virus which infects computers running Microsoft's Windows operating system has led to the slowing down and at times the shutting down of Internet systems due to excess traffic.