Twitter security engineers were cleaning up on Monday following a series of worm attacks over the weekend, including at least two credited to a bored 17-year-old.

In the first attack, which began early on Saturday, four new accounts began spreading a worm, compromising about 90 accounts, Twitter co-founder Biz Stone wrote in a posting on the Twitter blog.

The worms appeared to do no damage other than spread to infected users' followers and modify profile pages. You can get infected just by clic...